lesshat

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Current version: v4.1.0 (2016-07-19)

Get started

To use lesshat, you need node/npm installed then run npm install lesshat --save to install and save lesshat into your package.json. From here, you just need to reference the node_modules/lesshat/lesshat.less within your .less stylesheets.

Bower

Introduction

Why lesshat? In August 2012, while we were developing and extending CSS Hat for LESS we needed universal mixins. Unfortunately, none of available were good enough that would satisfy our needs and that’s why we created new custom ones on our own, which have become the most popular mixin library for the whole LESS CSS.

Meet the best mixins library in the world.

Features

• No restrictions – If it's possible in CSS, it must be possible to be done with a mixin. Unlimited number of anything, shadows, gradients, gradient swatches.
• Standard naming convention – In lesshat, mixins have names like all CSS3 properties. No .rounded or .shadow. It's stupid.
• Cross-browser – lesshat takes care of exporting CSS for all available browsers.
• Bootstrap friendly – You can now use prefixed lesshat version and gaily work with Bootstrap. Yeah it's that easy.
• Keyframes – Although it's tricky as hell, but yeah lesshat has mixin for .keyframes
• Blank state ready – If you call mixin without any arguments, lesshat does not pollute your CSS with empty properties. Instead lesshat generates nothing.
• Workflow – No more one line editing! We created developer friendly worklow for editing and creating mixins. You can test mixins with Mocha, generate new mixin with Grunt. Find out more about the workflow in Contribute section.

Structure of lesshat mixins

1. Typical lesshat mixin:

    .supermixin(...) {
    	@process: ~`(function(){})()`;
   
    	-webkit-border-radius: @process;
    	border-radius: @process;
    }
   

   In @process variable is all magic. Please don't edit javascript directly in .less file. Instead use lesshat-devstack.

2. Use (almost) every property without interpolation!

   Correct mixin calling:

    .background-image(linear-gradient(to bottom, #fb83fa 0%,#e93cec 100%))
   

   Incorrect calling:

    .background-image(~'linear-gradient(to bottom, #fb83fa 0%,#e93cec 100%)')
   

   Unfortunately, there are exceptions:

    .keyframes(~'');
    .calc(~'');
    .selection(~'');
   
    // in some cases you have to interpolate border-radius or LESS CSS begins to play on calculator
    .border-radius(~'20px / 40px');
   

Contribute:

1. Download this repo.
2. NPM install.
3. Now you have lesshat devstack (see documentation.)
4. If you create new mixin, use grunt generate command!
5. If it's possible (almost always) test the coverage for new mixins, and never break existing tests.
6. Commits should represent one logical change each. If a mixin goes through multiple iterations, squash your commits down to one.
7. Finally, commit some code and open a pull request.

Documentation:

List of mixins:

1. align-content flexbox
2. align-items flexbox
3. align-self flexbox
4. animation
5. animation-delay
6. animation-direction
7. animation-duration
8. animation-fill-mode
9. animation-iteration-count
10. animation-name
11. animation-play-state
12. animation-timing-function
13. appearance
14. backface-visibility
15. background-clip
16. background-image
17. background-origin
18. background-size
19. blur filter
20. border-bottom-left-radius
21. border-bottom-right-radius
22. border-image
23. border-radius
24. border-top-left-radius
25. border-top-right-radius
26. box-shadow
27. box-sizing
28. brightness filter
29. calc
30. column-count
31. column-gap
32. column-rule
33. column-width
34. columns
35. contrast filter
36. display flexbox
37. drop-shadow filter
38. filter
39. flex flexbox
40. flex-basis flexbox
41. flex-direction flexbox
42. flex-grow flexbox
43. flex-shrink flexbox
44. flex-wrap flexbox
45. font-face
46. grayscale filter
47. hue-rotate filter
48. hyphens
49. invert filter
50. justify-content flexbox
51. keyframes
52. opacity
53. order
54. perspective
55. perspective-origin
56. placeholder
57. rotate transform
58. rotate3d transform
59. rotateX transform
60. rotateY transform
61. rotateZ transform
62. saturate filter
63. scale transform
64. scale3d transform
65. scaleX transform
66. scaleY transform
67. scaleZ transform
68. selection
69. sepia filter
70. size width, height
71. skew transform
72. skewX transform
73. skewY transform
74. transform
75. transform-origin
76. transform-style
77. transition
78. transition-delay
79. transition-duration
80. transition-property
81. transition-timing-function
82. translate transform
83. translate3d transform
84. translateX transform
85. translateY transform
86. translateZ transform
87. user-select

• align-content

Summary:

The CSS align-content property aligns a flex container's lines within the flex container when there is an extra space on the cross-axis. This property has no effect on the single line flexible boxes.

Resources: MDN, CSS-Tricks

Syntax:

Default value: stretch

.align-content(flex-start | flex-end | center | space-between | space-around | stretch)

Example:

div {
 .align-content(flex-start);
}

// Result
div {
 -webkit-align-content: flex-start;
 -ms-flex-line-pack: start;
 align-content: flex-start;
} 

• align-items

Summary:

The CSS align-items property aligns flex items of the current flex line the same way as justify-content but in the perpendicular direction.

Resources: MDN, CSS-Tricks

Syntax:

Default value: stretch

.align-items(flex-start | flex-end | center | baseline | stretch)

Example:

div {
 .align-items(flex-start);
}

// Result
div {
 -webkit-box-align: flex-start;
 -moz-box-align: start;
 -webkit-align-items: start;
 -ms-flex-align: flex-start;
 align-items: flex-start;
}

• align-self

Summary:

The align-self CSS property aligns flex items of the current flex line overriding the align-items value. If any of the flex item's cross-axis margin is set to auto, then align-self is ignored.

Resources: MDN, CSS-Tricks

Syntax:

Default value: auto

.align-self(auto | flex-start | flex-end | center | baseline | stretch)

Example:

div {
 .align-self(flex-start);
}

// Result
div {
 -webkit-align-self: flex-start;
 -ms-flex-item-align: start;
 align-self: flex-start;
}

• animation

Summary:

Shorthand to define a CSS animation, setting all parameters at once.

Resources: WebPlatform, CSS3files

Syntax:

Default value: none

.animation(animation-name | animation-duration | animation-timing-function | animation-delay | animation-iteration-count | animation-direction | animation-fill-mode , […]*)

Example:

div {
 .animation(nameAnimation 2s linear alternate);
}

// Result
div {
 -webkit-animation: nameAnimation 2s linear alternate;
 -moz-animation: nameAnimation 2s linear alternate;
 -o-animation: nameAnimation 2s linear alternate;
 animation: nameAnimation 2s linear alternate;
}

• animation-delay

Summary:

Defines a length of time to elapse before an animation starts, allowing an animation to begin execution some time after it is applied.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.animation-delay(<time>, …)

Tips and tricks:

If you omit units after time argument, animation-delay is trying to be smart and add properly value.

if (time > 10) {
    time += 'ms';
  } else {
    time += 's';
  }

Example:

div {
 .animation-delay(2, 200);
}

// Result
div {
 -webkit-animation-delay: 2s, 200ms;
 -moz-animation-delay: 2s, 200ms;
 -o-animation-delay: 2s, 200ms;
 animation-delay: 2s, 200ms;
}

• animation-direction

Summary:

The animation-direction CSS property indicates whether the animation should play in reverse on alternate cycles.

Resources: WebPlatform, MDN

Syntax:

Default value: normal

.animation-direction(<single-animation-direction>, …)

Example:

div {
 .animation-direction(reverse, alternate);
}

// Result
div {
 -webkit-animation-direction: reverse, alternate;
 -moz-animation-direction: reverse, alternate;
 -o-animation-direction: reverse, alternate;
 animation-direction: reverse, alternate;
}

• animation-duration

Summary:

The animation-duration CSS property specifies the length of time that an animation should take to complete one cycle.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.animation-duration(<time>, …)

Tips and tricks:

If you omit units after time argument, animation-duration is trying to be smart and add proper value.

if (time > 10) {
    time += 'ms';
  } else {
    time += 's';
  }

Example:

div {
 .animation-duration(2000);
}

// Result
div {
 -webkit-animation-duration: 2000ms;
 -moz-animation-duration: 2000ms;
 -o-animation-duration: 2000ms;
 animation-duration: 2000ms;
}

• animation-fill-mode

Summary:

The animation-fill-mode CSS property specifies how a CSS animation should apply styles to its target before and after it is executing.

Resources: WebPlatform, MDN

Syntax:

Default value: none

.animation-fill-mode(<single-animation-fill-mode>, …)

Example:

div {
 .animation-fill-mode(forwards);
}

// Result
div {
 -webkit-animation-fill-mode: forwards;
 -moz-animation-fill-mode: forwards;
 -o-animation-fill-mode: forwards;
 animation-fill-mode: forwards;
}

• animation-iteration-count

Summary:

The animation-iteration-count CSS property specifies how a CSS animation should apply styles to its target before and after it is executing.

Resources: WebPlatform, MDN

Syntax:

Default value: 1

.animation-iteration-count(<single-animation-iteration-count>, …)

Example:

div {
 .animation-iteration-count(3);
}

// Result
div {
 -webkit-animation-iteration-count: 3;
 -moz-animation-iteration-count: 3;
 -o-animation-iteration-count: 3;
 animation-iteration-count: 3;
} 

• animation-name

Summary:

The animation-name CSS property specifies a list of animations that should be applied to the selected element. Each name indicates a @keyframes at-rule that defines the property values for the animation sequence.

Resources: WebPlatform, MDN

Syntax:

Default value: none

.animation-name(<single-animation-name>, …)

Example:

div {
 .animation-name(animation-1, animation-2);
}

// Result
div {
 -webkit-animation-name: animation-1, animation-2;
 -moz-animation-name: animation-1, animation-2;
 -o-animation-name: animation-1, animation-2;
 animation-name: animation-1, animation-2;
} 

• animation-play-state

Summary:

The animation-play-state CSS property determines whether an animation is running or paused. You can query this property's value to determine whether or not the animation is currently running; in addition, you can set its value to pause and resume playback of an animation.

Resources: WebPlatform, MDN

Syntax:

Default value: running

.animation-play-state(<single-animation-play-state>, …)

Example:

div {
 .animation-play-state(paused);
}

// Result
div {
 -webkit-animation-play-state: paused;
 -moz-animation-play-state: paused;
 -o-animation-play-state: paused;
 animation-play-state: paused;
} 

• animation-timing-function

Summary:

The animation-timing-function CSS property determines whether an animation is running or paused. You can query this property's value to determine whether or not the animation is currently running; in addition, you can set its value to pause and resume playback of an animation.

Resources: WebPlatform, MDN

Syntax:

Default value: ease

.animation-timing-function(<single-animation-timing-function>, …)

Example:

div {
 .animation-timing-function(cubic-bezier(0.1, 0.7, 1.0, 0.1));
}

// Result
div {
 -webkit-animation-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1);
 -moz-animation-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1);
 -o-animation-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1);
 animation-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1);
} 

• appearance

Summary:

Allows changing the style of any element to platform-based interface elements or vice versa.

Resources: WebPlatform, CSS-Tricks

Syntax:

Default value: none

.appearance(<appearance>)

Example:

div {
 .appearance();
}

// Result
div {
 -webkit-appearance: none;
 -moz-appearance: none;
 appearance: none;
} 

• backface-visibility

Summary:

The CSS backface-visibility property determines whether or not the back face of the element is visible when facing the user. The back face of an element always is a transparent background, letting, when visible, a mirror image of the front face be displayed.

Resources: WebPlatform, MDN

Syntax:

Default value: none

.backface-visibility(visible | hidden )

Example:

div {
 .backface-visibility(hidden);
}

// Result
div {
 -webkit-backface-visibility: none;
 -moz-backface-visibility: none;
 -ms-backface-visibility: none;
 -o-backface-visibility: none;
 backface-visibility: none;
} 

• background-clip

Summary:

The background-clip CSS property specifies whether an element's background, either the color or image, extends underneath its border.

Resources: WebPlatform, MDN

Syntax:

Default value: border-box

.background-clip(<box>)

Example:

div {
 .background-clip(padding-box);
}

// Result
div {
 -webkit-background-clip: padding-box;
 -moz-background-clip: padding-box;
 background-clip: padding-box;
} 

• background-image

Summary:

With the background-image you can create prefixed linear or radial gradients. The CSS (linear|radial)-gradient() function creates an <image> which represents a linear|radial gradient of colors. The result of this function is an object of the CSS <gradient> data type. Like any other gradient, a CSS linear gradient is not a CSS <color> but an image with no intrinsic dimensions; that is, it has neither natural or preferred size, nor ratio. Its concrete size will match the one of the element it applies to.

Resources: WebPlatform, MDN

Syntax:

Default value: none

.background-image(<gradient>, ...)

Tips and tricks:

The background-image mixin is the most robust mixin of all.
It generates SVG for Internet Explorer 9, old webkit, moz and opera syntax.
Always use W3C syntax for the mixin. It can recalculate angle for older syntax, transform to top to bottom syntax and it can omit SVG syntax if it's impossible to express SVG e.g. when you call mixin with 55deg.
If you call mixin without arguments, LESS Hat does not generate anything.
Great online gradient generator.

Example:

div {
 .background-image(linear-gradient(to bottom, #fb83fa 0%,#e93cec 100%));
}

// Result
div {
 background-image: url(data:image/svg+xml;base64,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);
 background-image: -webkit-linear-gradient(top, #fb83fa 0%, #e93cec 100%);
 background-image: -moz-linear-gradient(top, #fb83fa 0%, #e93cec 100%);
 background-image: -o-linear-gradient(top, #fb83fa 0%, #e93cec 100%);
 background-image: linear-gradient(to bottom, #fb83fa 0%, #e93cec 100%);
}

• background-origin

Summary:

The background-origin CSS property determines the background positioning area, that is the position of the origin of an image specified using the background-image CSS property.

Resources: WebPlatform, MDN

Syntax:

Default value: padding-box

.background-origin(<box>)

Example:

  div {
   .background-origin(content-box);
  }
  
  // Result
  div {
   -webkit-background-origin: content-box;
   -moz-background-origin: content-box;
   background-origin: content-box;
  } 

• background-size

Summary:

The background-size CSS property specifies the size of the background images. The size of the image can be fully constrained or only partially in order to preserve its intrinsic ratio.

Resources: WebPlatform, MDN

Syntax:

Default value: auto auto

.background-size(<bg-size>, ...)

Tips and tricks:

If you omit units, background-size adds px automatically.

Example:

div {
 .background-size(cover, 100%);
}

// Result
div {
 -webkit-background-size: cover, 100%;
 -moz-background-size: cover, 100%;
 background-size: cover, 100%;
} 

• blur (shorthand for filter property)

Summary:

Applies a Gaussian blur to the input image. The value of ‘radius’ defines the value of the standard deviation to the Gaussian function, or how many pixels on the screen blend into each other, so a larger value will create more blur. If no parameter is provided, then a value 0 is used. The parameter is specified as a CSS length, but does not accept percentage values.

Resources: MDN

Syntax:

Default value: 0

.blur(length)

Tips and tricks:

If you omit units, blur adds px automatically.

Example:

div {
 .blur(5px);
}

// Result
div {
 -webkit-filter: blur(5px);
 -moz-filter: blur(5px);
 -ms-filter: blur(5px);
 filter: blur(5px);
} 

• border-bottom-left-radius

Summary:

The border-bottom-left-radius CSS property sets the rounding of the bottom-left corner of the element. The rounding can be a circle or an ellipse, or if one of the value is 0 no rounding is done and the corner is square.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.border-bottom-left-radius(length | percentage)

Tips and tricks:

If you omit units, border-bottom-left-radius adds px automatically. If you want to use syntax like 10px \ 5px, you have to interpolate argument ~'' or LESS CSS divides it (yeah awesome feature!). Also LESS Hat adds background-clip: padding-box, because it fixes problem with older Safari. Here is some resource.

Example:

div {
 .border-bottom-left-radius(10px);
}

// Result
div {
 -webkit-border-bottom-left-radius: 10px;
 -moz-border-radius-bottomleft: 10px;
 border-bottom-left-radius: 10px;
}   

• border-bottom-right-radius

Summary:

The border-bottom-right-radius CSS property sets the rounding of the bottom-left corner of the element. The rounding can be a circle or an ellipse, or if one of the value is 0 no rounding is done and the corner is square.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.border-bottom-right-radius(length | percentage)

Tips and tricks:

If you omit units, border-bottom-right-radius adds px automatically. If you want to use syntax like 10px \ 5px, you have to interpolate argument ~'' or LESS CSS divides it (yeah awesome feature!). Also LESS Hat adds background-clip: padding-box, because it fixes problem with older Safari. Here is some resource.

Example:

  div {
   .border-bottom-right-radius(10px);
  }
  
  // Result
  div {
   -webkit-border-bottom-right-radius: 10px;
   -moz-border-radius-bottomright: 10px;
   border-bottom-right-radius: 10px;
  }   

• border-image

Summary:

The border-image CSS property allows drawing an image on the borders of elements. This makes drawing complex looking widgets much simpler than it has been and removes the need for nine boxes in some cases.

Resources: WebPlatform, MDN

Syntax:

Default value: based on individual properties

.border-image(border-image-source border-image-slice border-image-width border-image-outset border-image-repeat)

Tips and tricks:

If you call mixin without arguments, LESS Hat does not generate anything. Good border-image online generator.

Example:

div {
 .border-image(url(border.png) 61 45 62 54 repeat);
}

// Result
div {
 -webkit-border-image: url(border.png) 61 45 62 54 repeat;
 -moz-border-image: url(border.png) 61 45 62 54 repeat;
 -o-border-image: url(border.png) 61 45 62 54 repeat;
 border-image: url(border.png) 61 45 62 54 repeat;
} 

• border-radius

Summary:

The border-radius CSS property allows Web authors to define how rounded border corners are. The curve of each corner is defined using one or two radii, defining its shape: circle or ellipse.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.border-radius(length | percentage | length / length | percentage / percentage)

Tips and tricks:

If you omit units, border-radius adds px automatically. If you want to use syntax like 10px \ 5px, you have to interpolate argument ~'' or LESS CSS divides it (yeah awesome feature!). Also LESS Hat adds background-clip: padding-box, because it fixes problem with older Safari. Here is some resource.

Example:

div {
 .border-radius(5px);
}

// Result
div {
 -webkit-border-radius: 5px;
 -moz-border-radius: 5px;
 border-radius: 5px;
} 

• border-top-left-radius

Summary:

The border-top-left-radius CSS property sets the rounding of the top-left corner of the element. The rounding can be a circle or an ellipse, or if one of the value is 0 no rounding is done and the corner is square.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.border-top-left-radius(length | percentage)

Tips and tricks:

If you omit units, border-top-left-radius adds px automatically. If you want to use syntax like 10px \ 5px, you have to interpolate argument ~'' or LESS CSS divides it (yeah awesome feature!). Also LESS Hat adds background-clip: padding-box, because it fixes problem with older Safari. Here is some resource.

Example:

div {
 .border-top-left-radius(5px);
}

// Result
div {
 -webkit-border-top-left-radius: 5px;
 -moz-border-top-left-radius: 5px;
 border-top-left-radius: 5px;
} 

• border-top-right-radius

Summary:

The border-top-right-radius CSS property sets the rounding of the top-right corner of the element. The rounding can be a circle or an ellipse, or if one of the value is 0 no rounding is done and the corner is square.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.border-top-right-radius(length | percentage)

Tips and tricks:

If you omit units, border-top-right-radius adds px automatically. If you want to use syntax like 10px \ 5px, you have to interpolate argument ~'' or LESS CSS divides it (yeah awesome feature!). Also LESS Hat adds background-clip: padding-box, because it fixes problem with older Safari. Here is some resource.

Example:

div {
 .border-top-right-radius(5px);
}

// Result
div {
 -webkit-border-top-right-radius: 5px;
 -moz-border-top-right-radius: 5px;
 border-top-right-radius: 5px;
} 

• box-shadow

Summary:

The box-shadow CSS property describes one or more shadow effects as a comma-separated list. It allows casting a drop shadow from the frame of almost any element. If a border-radius is specified on the element with a box shadow, the box shadow takes on the same rounded corners. The z-ordering of multiple box shadows is the same as multiple text shadows (the first specified shadow is on top).

Resources: WebPlatform, MDN

Syntax:

Default value: none

.box-shadow(<offset-x> <offset-y> spread blur-radius color inset, …)

Tips and tricks:

If you omit units, box-shadow adds px automatically.

Example:

div {
 .box-shadow(0 1px 10px rgba(20,20,20,0.5));
}

// Result
div {
 -webkit-box-shadow: 0 1px 10px rgba(20,20,20,0.5);
 -moz-box-shadow: 0 1px 10px rgba(20,20,20,0.5);
 box-shadow: 0 1px 10px rgba(20,20,20,0.5);
} 

• box-sizing

Summary:

The box-sizing CSS property is used to alter the default CSS box model used to calculate widths and heights of elements. It is possible to use this property to emulate the behavior of browsers that do not correctly support the CSS box model specification.

Resources: WebPlatform, MDN

Syntax:

Default value: content-box

.box-sizing(content-box | padding-box | border-box)

Example:

div {
 .box-sizing(padding-box);
}

// Result
div {
 -webkit-box-sizing: padding-box;
 -moz-box-sizing: padding-box;
 box-sizing: padding-box;
}

• brightness (shorthand for filter property)

Summary:

Applies a linear multiplier to input image, making it appear more or less bright. A value of 0% will create an image that is completely black. A value of 100% leaves the input unchanged. Other values are linear multipliers on the effect. Values of an amount over 100% are allowed, providing brighter results. If the ‘amount’ parameter is missing, a value of 100% is used.

Resources: MDN

Syntax:

Default value: 0

.brightness(amount)

Example:

div {
 .brightness(0.5);
}

// Result
div {
 -webkit-filter: brightness(0.5);
 -moz-filter: brightness(0.5);
 -ms-filter: brightness(0.5);
 filter: brightness(0.5);
} 

• calc

Summary:

The calc() CSS function can be used anywhere a <length>, <frequency>, <angle>, <time>, <number>, or <integer> is required.With calc(), you can perform calculations to determine CSS property values.

THIS MIXIN MUST BE INTERPOLATED ~''
The -lh-property: 0 junk line of code is a neccesary sacrifice due to the hack nature of this set of mixins. (via less-properties)

Resources: MDN

Syntax:

.calc(<element>, ~'<expression>')

Example:

div {
 .calc(width, ~'100% - 33px');
}

// Result
div {
 -lh-property: 0;
 width:-webkit-calc(100% - 33px);
 width:-moz-calc(100% - 33px);
 width:calc(100% - 33px);
} 

• column-count

Summary:

The column-count CSS property describes the number of columns of the element.

Resources: WebPlatform, MDN

Syntax:

Default value: auto

.column-count(<number> | auto)

Example:

div {
 .column-count(3);
}

// Result
div {
 -webkit-column-count: 0.5;
 -moz-column-count: 0.5;
 column-count: 0.5;
}   

• column-gap

Summary:

The column-gap CSS property sets the size of the gap between columns for elements which are specified to display as a multi-column element.

Resources: WebPlatform, MDN

Syntax:

Default value: normal

.column-gap(<length> | normal)

Tips and tricks:

If you omit units, column-gap adds px automatically.

Example:

div {
 .column-gap(30);
}

// Result
div {
 -webkit-column-gap: 30px;
 -moz-column-gap: 30px;
 column-gap: 30px;
}   

• column-rule

Summary:

In multi-column layouts, the column-rule CSS property specifies a straight line, or "rule", to be drawn between each column.

Resources: WebPlatform, MDN

Syntax:

Default value: medium none black

.column-rule(<column-rule-width> | <column-rule-style> | <column-rule-color>)

Tips and tricks:

If you omit units, column-rule adds px automatically.

Example:

div {
 .column-rule(5 outset #ff00ff);
}

// Result
div {
 -webkit-column-rule: 5px outset #ff00ff;
 -moz-column-rule: 5px outset #ff00ff;
 column-rule: 5px outset #ff00ff;
} 

• column-width

Summary:

The column-width CSS property suggests an optimal column width. This is not a absolute value but a mere hint. Browser will adjust the width of the column around that suggested value, allowing to achieve scalable designs that fit different screen size.

Resources: WebPlatform, MDN

Syntax:

Default value: auto

.column-width(<length> | auto)

Tips and tricks:

If you omit units, column-width adds px automatically.

Example:

div {
 .column-width(100px);
}

// Result
div {
 -webkit-column-width: 100px;
 -moz-column-width: 100px;
 column-width: 100px;
}  

• columns

Summary:

The columns CSS property is a shorthand property allowing to set both the column-width and the column-count properties at the same time.

Resources: WebPlatform, MDN

Syntax:

Default value: auto

.columns(<column-width> | <column-count>)

Tips and tricks:

If you omit units for column-width argument, columns adds px to it automatically.

Example:

div {
 .columns(100 3);
}

// Result
div {
 -webkit-columns: 100px 3;
 -moz-columns: 100px 3;
 columns: 100px 3;
} 

• contrast

Summary:

Adjusts the contrast of the input. A value of 0% will create an image that is completely black. A value of 100% leaves the input unchanged. Values of amount over 100% are allowed, providing results with less contrast. If the ‘amount’ parameter is missing, a value of 100% is used.

Resources: MDN

Syntax:

Default value: 100%

.contrast(<amount>)

Tips and tricks:

If you omit units, contrast adds % automatically.

Example:

div {
 .contrast(200);
}

// Result
div {
 -webkit-filter: contrast(200%);
 -moz-filter: contrast(200%);
 -ms-filter: contrast(200%);
 filter: contrast(200%);
} 

• display

Summary:

The display CSS property specifies the type of rendering box used for an element. This mixin is specifically for flexbox purpose.

Resources: CSS-Tricks

Syntax:

.display(<flex> | <inline-flex>)

Example:

div {
 .display(flex);
}

// Result
div {
 display: -webkit-box;
 display: -ms-flexbox;
 display: -webkit-flex;
 display: -moz-box;
} 

• drop-shadow

Summary:

Applies a drop shadow effect to the input image. A drop shadow is effectively a blurred, offset version of the input image's alpha mask drawn in a particular color, composited below the image.

Resources: MDN

Syntax:

.drop-shadow(<offset-x> <offset-y> [<blur-radius> | <spread-radius> | <color>])

Tips and tricks:

If you omit units, drop-shadow adds px automatically.

Example:

div {
 .drop-shadow(16 16 10 black);
}

// Result
div {
 -webkit-filter: drop-shadow(16px 16px 10px #000000);
 -moz-filter: drop-shadow(16px 16px 10px #000000);
 -ms-filter: drop-shadow(16px 16px 10px #000000);
 filter: drop-shadow(16px 16px 10px #000000);
} 

• filter

Summary:

The CSS filter property provides for effects like blurring or color shifting on an element’s rendering before the element is displayed. Filters are commonly used to adjust the rendering of an image, a background, or a border.

Resources: MDN

Syntax:

Default value: none

.filter(<filter-function>*)

Example:

div {
 .filter(grayscale(0.5) blur(10px));
}

// Result
div {
 -webkit-filter: grayscale(0.5) blur(10px);
 -moz-filter: grayscale(0.5) blur(10px);
 -ms-filter: grayscale(0.5) blur(10px);
 filter: grayscale(0.5) blur(10px);
}

• flex

Summary:

The flex CSS property specifies ability of a flex item to alter their dimensions to fill the available space. Flex items can be stretched to use available space proportional to their flex grow factor or their flex shrink factor to prevent overflow.

Resources: MDN, CSS-Tricks

Syntax:

Default value: 0 1 auto

.flex(none | [ <flex-grow> <flex-shrink> | <flex-basis> ])

Example:

div {
 .flex(1 3 100px);
}

// Result
div {
 -webkit-box-flex: 1;
 -moz-box-flex: 1;
 -webkit-flex: 1 3 100px;
 -ms-flex: 1 3 100px;
 flex: 1 3 100px;
}

• flex-basis

Summary:

The CSS flex-basis property specifies the flex basis which is the initial main size of a flex item.

Resources: MDN, CSS-Tricks

Syntax:

Default value: auto

.flex-basis(<width>)

Tips and tricks:

If you omit units, flex-basis adds px automatically.

Example:

div {
 .flex-basis(100);
}

// Result
div {
 -webkit-flex-basis: 100;
 flex-basis: 100px;
}

• flex-direction

Summary:

The CSS flex-direction property specifies how flex items are placed in the flex container defining the main axis and the direction (normal or reversed).

Resources: MDN, CSS-Tricks

Syntax:

Default value: row

.flex-direction(row | row-reverse | column | column-reverse) 

Example:

div {
 .flex-direction(row);
}

// Result
div {
 -webkit-box-direction: normal;
 -moz-box-direction: normal;
 -webkit-box-orient: horizontal;
 -moz-box-orient: horizontal;
 -webkit-flex-direction: row;
 -ms-flex-direction: row;
 flex-direction: row;
}

• flex-grow

Summary:

The CSS flex-grow property specifies the flex grow factor of a flex item.

Resources: MDN, CSS-Tricks

Syntax:

Default value: 0

.flex-grow(<number>) 

Example:

div {
 .flex-grow(2);
}

// Result
div {
 -webkit-flex-grow: 2;
 flex-grow: 2;
}

• flex-shrink

Summary:

The CSS flex-shrink property specifies the flex shrink factor of a flex item.

Resources: MDN, CSS-Tricks

Syntax:

Default value: 1

.flex-shrink(<number>) 

Example:

div {
 .flex-shrink(2);
}

// Result
div {
 -webkit-flex-shrink: 2;
 flex-shrink: 2;
}

• flex-wrap

Summary:

The CSS flex-wrap property specifies whether the children are forced into a single line or if the items can be flowed on multiple lines.

Resources: MDN, CSS-Tricks

Syntax:

Default value: nowrap

.flex-wrap(nowrap | wrap | wrap-reverse) 

Example:

div {
 .flex-wrap(wrap-reverse);
}

// Result
div {
 -webkit-flex-wrap: 2;
 -ms-flex-wrap: 2;
 flex-wrap: 2;
}

• font-face

Summary:

The @font-face CSS at-rule allows authors to specify online fonts to display text on their web pages.

Resources: MDN

Syntax:

.font-face(@fontname, @fontfile, @fontweight:normal, @fontstyle:normal) 

Example:

div {
 .font-face(Hipster, ~'../fonts/hipster', bold, italic);
}

// Result
div {
 font-family: "Hipster";
 src: url("../fonts/hipster.eot");
 src: url("../fonts/hipster.eot?#iefix") format("embedded-opentype"), url("../fonts/hipster.woff") format("woff"), url("../fonts/hipster.ttf") format("truetype"), url("../fonts/hipster.svg#Hipster") format("svg");
 font-weight: bold;
 font-style: italic;
}

• grayscale

Summary:

Converts the input image to grayscale. The value of ‘amount’ defines the proportion of the conversion. A value of 100% is completely grayscale. A value of 0% leaves the input unchanged. Values between 0% and 100% are linear multipliers on the effect. If the ‘amount’ parameter is missing, a value of 100% is used.

Resources: MDN

Syntax:

Default value: 0

.grayscale(<percentage>) 

Tips and tricks:

If you omit units, grayscale adds % automatically.

Example:

div {
 .grayscale(50);
}

// Result
div {
 -webkit-filter: grayscale(50%);
 -moz-filter: grayscale(50%);
 -ms-filter: grayscale(50%);
 filter: grayscale(50%);
}

• hue-rotate

Summary:

Applies a hue rotation on the input image. The value of ‘angle’ defines the number of degrees around the color circle the input samples will be adjusted. A value of 0deg leaves the input unchanged. If the ‘angle’ parameter is missing, a value of 0deg is used. Maximum value is 360deg.

Resources: MDN

Syntax:

Default value: 0

.hue-rotate(<percentage>) 

Tips and tricks:

If you omit units, hue-rotate adds deg automatically.

Example:

div {
 .hue-rotate(50);
}

// Result
div {
 -webkit-filter: hue-rotate(50deg);
 -moz-filter: hue-rotate(50deg);
 -ms-filter: hue-rotate(50deg);
 filter: hue-rotate(50deg);
}

• hyphens

Summary:

The hyphens CSS property tells the browser how to go about splitting words to improve the layout of text when line-wrapping.

Resources: MDN

Syntax:

Default value: manual

.hyphens(none | manual | auto)

Example:

div {
 .hyphens(none);
}

// Result
div {
 -webkit-hyphens: none;
 -moz-hyphens: none;
 -ms-hyphens: none;
} 

• invert

Summary:

Inverts the samples in the input image. The value of ‘amount’ defines the proportion of the conversion. A value of 100% is completely inverted. A value of 0% leaves the input unchanged. Values between 0% and 100% are linear multipliers on the effect. If the ‘amount’ parameter is missing, a value of 100% is used.

Resources: MDN

Syntax:

Default value: 0

.invert(<percentage>) 

Tips and tricks:

If you omit units, invert adds % automatically.

Example:

div {
 .invert(100);
}

// Result
div {
 -webkit-filter: invert(100%);
 -moz-filter: invert(100%);
 -ms-filter: invert(100%);
 filter: invert(100%);
}

• justify-content

Summary:

The CSS justify-content property defines how a browser distributes available space between and around elements when aligning flex items in the main-axis of the current line.

Resources: MDN, CSS-Tricks

Syntax:

Default value: flex-start

.justify-content(flex-start | flex-end | center | space-between | space-around) 

Example:

div {
 .justify-content(flex-start);
}

// Result
div {
 -webkit-box-pack: flex-start;
 -moz-box-pack: start;
 -webkit-justify-content: start;
 -ms-flex-pack: flex-start;
 justify-content: flex-start;
}

• keyframes

Summary:

The @keyframes CSS at-rule lets authors control the intermediate steps in a CSS animation sequence by establishing keyframes (or waypoints) along the animation sequence that must be reached by certain points during the animation.

LESS CSS isn't great for complicated mixin like this one, so it's little bit tricky. LESS CSS compiler doesn't allow to have properties in the root. It's better to understand the problem on the example.

// There is no selector
color: red;

SyntaxError: properties must be inside selector blocks, they cannot be in the root. 

div { color: red; } // This is correct

Therefore LESS Hat generates placeholder selector lesshat-selector { -lh-property: 0; } with unknown property, which browsers ignore and after that, there is actually keyframes syntax.

And also because of bad architecture of LESS CSS language, keyframes definition has to be on single line.

THIS MIXIN MUST BE INTERPOLATED ~''

Resources: WebPlatform, MDN

Syntax:

.keyframes(~'<keyframes-name>, <keyframes-definition>') 

Tips and tricks:

Properties inside <keyframes-definition> are automatically prefixed, if it's needed.
Keyframes mixin supports prefix configuration but it's computationally demanding so it is commented out and all prefixes are rendered. Feel free to uncommented that if you need it.

Example:

.keyframes(~'animationName, 0%{ transform: scale(1.5); color: blue; } 100%{ transform: scale(2); color: red }');

// Result
 lesshat-selector {-lh-property: 0; } 
 @-webkit-keyframes animationName{ 0%{ -webkit-transform: scale(1.5); color: blue; } 100%{ -webkit-transform: scale(2); color: red }}
 @-moz-keyframes animationName{ 0%{ -moz-transform: scale(1.5); color: blue; } 100%{ -moz-transform: scale(2); color: red }}
 @-o-keyframes animationName{ 0%{ -o-transform: scale(1.5); color: blue; } 100%{ -o-transform: scale(2); color: red }}
 @keyframes animationName{ 0%{ transform: scale(1.5); color: blue; } 100%{ transform: scale(2); color: red };} 

• opacity

Summary:

The opacity CSS property specifies the transparency of an element, that is, the degree to which the background behind the element is overlaid.

This is not shorthand method for filter opacity.

Resources: MDN

Syntax:

Default value: 1

.opacity(<number>) 

Tips and tricks:

You can enable old filter syntax for IE6, just set @ms_local: true.

Example:

div {
 .opacity(.5);
}

// Result
div {
 -webkit-opacity: 0.5;
 -moz-opacity: 0.5;
 opacity: 0.5;
}

• order

Summary:

The CSS order property specifies the order used to lay out flex items in their flex container.

Resources: MDN, CSS-Tricks

Syntax:

Default value: 0

.order(<integer>) 

Example:

div {
 .order(1);
}

// Result
div {
 -webkit-box-ordinal-group: 1;
 -moz-box-ordinal-group: 1;
 -ms-flex-order: 1;
 -webkit-order: 1;
 order: 1;
}

• perspective

Summary:

The perspective CSS property determines the distance between the z=0 plane and the user in order to give to the 3D-positioned element some perspective.

Resources: MDN, CSS-Tricks

Syntax:

Default value: none

.perspective(none | <length>)

Tips and tricks:

If you omit units, perspective adds px automatically.

Example:

div {
 .perspective(1000);
}

// Result
div {
 -moz-perspective: 1000px;
 -webkit-perspective: 1000px;
 perspective: 1000px;
}

• perspective-origin

Summary:

The perspective-origin CSS property determines the position the viewer is looking at. It is used as the vanishing point by the perspective property.

Resources: MDN, CSS-Tricks

Syntax:

Default value: 50% 50%

.perspective-origin(<percentage> | <length> | constants | inherit)

Tips and tricks:

If you omit units, perspective-origin adds % automatically.

Example:

div {
 .perspective-origin(top left);
}

// Result
div {
 -moz-perspective-origin: top left;
 -webkit-perspective-origin: top left;
 perspective-origin: top left;
}

• placeholder

Summary:

Placeholder is the short hint displayed in the input field before the user clicked to it. Default placeholder text in inputs has a light gray color (so far).

Resources: CSS-Tricks

Syntax:

.placeholder(<color>, [<element>])

Example:

div {
 .placeholder(#666666);
}

// Result
div::-webkit-input-placeholder {
   color: #666666;
}
div:-moz-placeholder {
   color: #666666;
}
div::-moz-placeholder {
   color: #666666;
}
div:-ms-input-placeholder {
   color: #666666;
}

// In root (outside of selectors)
.placeholder(#333333);

// Result
::-webkit-input-placeholder {
   color: #666666;
}
:-moz-placeholder {
   color: #666666;
}
::-moz-placeholder {
   color: #666666;
}
:-ms-input-placeholder {
   color: #666666;
}

// In root (outside of selectors)
.placeholder(#333333, textarea);

// Result
textarea::-webkit-input-placeholder {
   color: #666666;
}
textarea:-moz-placeholder {
   color: #666666;
}
textarea::-moz-placeholder {
   color: #666666;
}
textarea:-ms-input-placeholder {
   color: #666666;
}

• rotate

Summary:

Rotates the element clockwise around its origin by the specified angle.

Resources: MDN

Syntax:

Default value: 0

.rotate(<angle>)

Tips and tricks:

If you omit units, rotate adds deg automatically.

Example:

div {
 .rotate(45);
}

// Result
div {
 -webkit-transform: rotate(45deg);
 -moz-transform: rotate(45deg);
 -ms-transform: rotate(45deg);
 -o-transform: rotate(45deg);
 transform: rotate(45deg);
}

• rotate3d

Summary:

The rotate3d()CSS function defines a transformation that moves the element around a fixed axe without deforming it.

Resources: MDN

Syntax:

Default value: 0, 0, 0, 0

.rotate3d(<number>, <number>, <number>, <angle>)

Tips and tricks:

If you omit angle unit, rotate3d adds deg automatically.

Example:

div {
 .rotate3d(1, 0, 0, 50);
}

// Result
div {
 -webkit-transform: rotate3d(1, 0, 0, 50deg);
 -moz-transform: rotate3d(1, 0, 0, 50deg);
 -ms-transform: rotate3d(1, 0, 0, 50deg);
 -o-transform: rotate3d(1, 0, 0, 50deg);
 transform: rotate3d(1, 0, 0, 50deg);
}

• rotateX

Summary:

The rotateX() CSS function defines a transformation that moves the element around the abscissa without deforming it.

Resources: MDN

Syntax:

Default value: 0

.rotateX(<angle>)

Tips and tricks:

If you omit units, rotateX adds deg automatically.

Example:

div {
 .rotateX(45);
}

// Result
div {
 -webkit-transform: rotateX(45deg);
 -moz-transform: rotateX(45deg);
 -ms-transform: rotateX(45deg);
 -o-transform: rotateX(45deg);
 transform: rotateX(45deg);
}

• rotateY

Summary:

The rotateY() CSS function defines a transformation that moves the element around the ordinate without deforming it.

Resources: MDN

Syntax:

Default value: 0

.rotateY(<angle>)

Tips and tricks:

If you omit units, rotateY adds deg automatically.

Example:

div {
 .rotateY(45);
}

// Result
div {
 -webkit-transform: rotateY(45deg);
 -moz-transform: rotateY(45deg);
 -ms-transform: rotateY(45deg);
 -o-transform: rotateY(45deg);
 transform: rotateY(45deg);
}

• rotateZ

Summary:

The rotateZ() CSS function defines a transformation that moves the element around the z-axis without deforming it.

Resources: MDN

Syntax:

Default value: 0

.rotateZ(<angle>)

Tips and tricks:

If you omit units, rotateZ adds deg automatically.

Example:

div {
 .rotateZ(45);
}

// Result
div {
 -webkit-transform: rotateZ(45deg);
 -moz-transform: rotateZ(45deg);
 -ms-transform: rotateZ(45deg);
 -o-transform: rotateZ(45deg);
 transform: rotateZ(45deg);
}

• saturate

Summary:

Saturates the input image. The value of ‘amount’ defines the proportion of the conversion.

Resources: MDN

Syntax:

Default value: 100%

.saturate(<amount>)

Tips and tricks:

If you omit units, saturate adds % automatically.

Example:

div {
 .saturate(45);
}

// Result
div {
 -webkit-filter: saturate(45deg);
 -moz-filter: saturate(45deg);
 -ms-filter: saturate(45deg);
 filter: saturate(45deg);
}

• scale

Summary:

Specifies a 2D scaling operation described by [sx, sy]. If sy isn't specified, it is assumed to be equal to sx.

Resources: MDN

Syntax:

Default value: 1

.scale(<sx>[, <sy>]) 

Example:

div {
 .scale(2);
}

// Result
div {
 -webkit-transform: scale(2);
 -moz-transform: scale(2);
 -ms-transform: scale(2);
 -o-transform: scale(2);
 transform: scale(2);
}

• scale3d

Summary:

The scale3d() CSS function modifies the size of an element. Because the amount of scaling is defined by a vector, it can resize different dimensions at different scales.

Resources: MDN

Syntax:

Default value: 1, 1, 1

.scale3d(<sx>, <sy>, <sz>) 

Example:

div {
 .scale3d(1.5, .2, 3);
}

// Result
div {
 -webkit-transform: scale3d(1.5, 0.2, 3);
 -moz-transform: scale3d(1.5, 0.2, 3);
 -ms-transform: scale3d(1.5, 0.2, 3);
 -o-transform: scale3d(1.5, 0.2, 3);
 transform: scale3d(1.5, 0.2, 3);
}

• scaleX

Summary:

Specifies a scale operation using the vector [sx, 1].

Resources: MDN

Syntax:

Default value: 1

.scaleX(<sx>) 

Example:

div {
 .scaleX(1.5);
}

// Result
div {
 -webkit-transform: scaleX(1.5);
 -moz-transform: scaleX(1.5);
 -ms-transform: scaleX(1.5);
 -o-transform: scaleX(1.5);
 transform: scaleX(1.5);
}

• scaleY

Summary:

Specifies a scale operation using the vector [1, sy].

Resources: MDN

Syntax:

Default value: 1

.scaleY(<sy>) 

Example:

div {
 .scaleY(1.5);
}

// Result
div {
 -webkit-transform: scaleY(1.5);
 -moz-transform: scaleY(1.5);
 -ms-transform: scaleY(1.5);
 -o-transform: scaleY(1.5);
 transform: scaleY(1.5);
}

• scaleZ

Summary:

The scaleZ() CSS function modifies the z-coordinate of each element point by a constant facto, except if this scale factor is 1, in which case the function is the identity transform.

Resources: MDN

Syntax:

Default value: 1

.scaleZ(<sz>) 

Example:

div {
 .scaleZ(1.5);
}

// Result
div {
 -webkit-transform: scaleZ(1.5);
 -moz-transform: scaleZ(1.5);
 -ms-transform: scaleZ(1.5);
 -o-transform: scaleZ(1.5);
 transform: scaleZ(1.5);
}

• selection

Summary:

The ::selection CSS pseudo-element applies rules to the portion of a document that has been highlighted. LESS CSS compiler doesn't allow to have properties in the root. It's better to understand the problem on the example.

// There is no selector
color: red;

SyntaxError: properties must be inside selector blocks, they cannot be in the root. 

div { color: red; } // This is correct

Therefore LESS Hat generates placeholder selector lesshat-selector { -lh-property: 0; } with unknown property, which browsers ignore and after that, there is actually selection syntax.

THIS MIXIN MUST BE INTERPOLATED ~''

Use this mixin outside of CSS selectors

Resources: MDN

Syntax:

.selection(<CSS properties>[, <element>]) 

Example:

.selection(~'color: blue; background: red');

// Result
lesshat-selector {-lh-property: 0;} 
::selection{color: blue; background: red}
::-moz-selection{color: blue; background: red;}

• sepia

Summary:

Converts the input image to Instagram like effect.

Resources: MDN

Syntax:

.sepia(<percentage>) 

Tips and tricks:

If you omit units, sepia adds % automatically.

Example:

div {
 .sepia(50);
}

// Result
div {
 -webkit-filter: sepia(50%);
 -moz-filter: sepia(50%);
 filter: sepia(50%);
}

• size

Summary:

This is helper mixin for fast dimensions setup.

Syntax:

.size(<width>, [<height>]) 

Tips and tricks:

When you call mixin with only one argument, second will be the same. Also you can omit units and size adds it automatically.

Example:

div {
 .size(50);
}

// Result
div {
 width: 50px;
 height: 50px;
}

• skew

Summary:

Skews the element along the X and Y axes by the specified angles. If ay isn't provided, no skew is performed on the Y axis.

Resources: MDN

Syntax:

Default value: 0

.skew(<ax>[, <ay>]) 

Tips and tricks:

If you omit units, skew adds % automatically.

Example:

div {
 .skew(20, 30);
}

// Result
div {
 -webkit-transform: skew(20deg, 30deg);
 -moz-transform: skew(20deg, 30deg);
 -ms-transform: skew(20deg, 30deg);
 -o-transform: skew(20deg, 30deg);
 transform: skew(20deg, 30deg);
}

• skewX

Summary:

Skews the element along the X axis by the given angle.

Resources: MDN

Syntax:

Default value: 0

.skewX(<angle>) 

Tips and tricks:

If you omit units, skewX adds % automatically.

Example:

div {
 .skewX(20);
}

// Result
div {
 -webkit-transform: skewX(20deg);
 -moz-transform: skewX(20deg);
 -ms-transform: skewX(20deg);
 -o-transform: skewX(20deg);
 transform: skewX(20deg);
}

• skewY

Summary:

Skews the element along the Y axis by the given angle.

Resources: MDN

Syntax:

Default value: 0

.skewY(<angle>) 

Tips and tricks:

If you omit units, skewY adds % automatically.

Example:

div {
 .skewY(20);
}

// Result
div {
 -webkit-transform: skewY(20deg);
 -moz-transform: skewY(20deg);
 -ms-transform: skewY(20deg);
 -o-transform: skewY(20deg);
 transform: skewY(20deg);
}

• transform

Summary:

The CSS transform property lets you modify the coordinate space of the CSS visual formatting model.

Resources: WebPlatform, MDN

Syntax:

Default value: none

.transform(none | <transform-function>+) 

Tips and tricks:

If you omit units, transform can adds correct unit automatically.

 translate: 'px',
 rotate: 'deg',
 rotate3d: 'deg',
 skew: 'deg'

Example:

div {
 .transform(scale(.5) translate(10, 20));
}

// Result
div {
 -webkit-transform: scale(.5) translate(10, 20);
 -moz-transform: scale(.5) translate(10, 20);
 -ms-transform: scale(.5) translate(10, 20);
 -o-transform: scale(.5) translate(10, 20);
 transform: scale(.5) translate(10, 20);
}

• transform-origin

Summary:

The transform-origin CSS property lets you modify the origin for transformations of an element.

Resources: WebPlatform, MDN

Syntax:

Default value: 50% 50% 0

.transform-origin(<percentage> | <length> | <named-position>) 

Tips and tricks:

If you omit units, transform-origin adds % automatically.

Example:

div {
 .transform-origin(50 50);
}

// Result
div {
 -webkit-transform-origin: 50% 50%;
 -moz-transform-origin: 50% 50%;
 -ms-transform-origin: 50% 50%;
 -o-transform-origin: 50% 50%;
 transform-origin: 50% 50%;
}

• transform-style

Summary:

The transform-style CSS property determines if the children of the element are positioned in the 3D-space or are flattened in the plane of the element.

Resources: WebPlatform, MDN

Syntax:

Default value: flat

.transform-style(flat | preserve-3d) 

Example:

div {
 .transform-style(preserve-3d);
}

// Result
div {
 -webkit-transform-style: preserve-3d;
 -moz-transform-style: preserve-3d;
 -ms-transform-style: preserve-3d;
 -o-transform-style: preserve-3d;
 transform-style: preserve-3d;
}

• transition

Summary:

The CSS transition property is a shorthand property for transition-property, transition-duration, transition-timing-function, and transition-delay. It allows to define the transition between two states of an element.

Resources: WebPlatform, MDN

Syntax:

Default value: all 0 ease 0

.transition([ none | <single-transition-property> ] | <time> | <timing-function> | <time>)

Tips and tricks:

If you omit units after time argument, transition is trying to be smart and add properly value.

  if (time > 10) {
      time += 'ms';
    } else {
      time += 's';
    }

And also properties inside transition definition are automatically prefixed, if it is needed.
W3C property value is appending all prefixed values.
Why? Some browsers support W3C unprefixed properties, but values must be sometimes prefixed. Let's consider this example:

div {
-webkit-transition: -webkit-filter .3s ease;
-moz-transition: -moz-filter .3s ease;
-o-transition: filter .3s ease;

// There is a problem! Webkit needs -webkit-filter property
transition: filter .3s ease;
}

Example:

div {
 .transition(box-shadow 0.2s linear, color .4s .2s ease);
}

// Result
div {
 -webkit-transition: -webkit-box-shadow 0.2s linear, color 0.4s 0.2s ease;
 -moz-transition: -moz-box-shadow 0.2s linear, color 0.4s 0.2s ease;
 -o-transition: box-shadow 0.2s linear, color 0.4s 0.2s ease;
 transition: box-shadow 0.2s linear, color 0.4s 0.2s ease;
}

• transition-delay

Summary:

The transition-delay CSS property specifies the amount of time to wait between a change being requested to a property that is to be transitioned and the start of the transition effect.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.transition-delay(<time>)

Tips and tricks:

If you omit units after time argument, transition-delay is trying to be smart and add properly value.

  if (time > 10) {
      time += 'ms';
    } else {
      time += 's';
    }

Example:

div {
 .transition-delay(200);
}

// Result
div {
 -webkit-transition-delay: 200ms;
 -moz-transition-delay: 200ms;
 -o-transition-delay: 200ms;
 transition-delay: 200ms;
}

• transition-duration

Summary:

The transition-duration CSS property specifies the number of seconds or milliseconds a transition animation should take to complete. By default, the value is 0s, meaning that no animation will occur.

Resources: WebPlatform, MDN

Syntax:

Default value: 0

.transition-duration(<time>)

Tips and tricks:

If you omit units after time argument, transition-duration is trying to be smart and add properly value.

  if (time > 10) {
      time += 'ms';
    } else {
      time += 's';
    }

Example:

div {
 .transition-duration(6);
}

// Result
div {
 -webkit-transition-duration: 6s;
 -moz-transition-duration: 6s;
 -o-transition-duration: 6s;
 transition-duration: 6s;
}

• transition-property

Summary:

The transition-property CSS property is used to specify the names of CSS properties to which a transition effect should be applied.

Resources: WebPlatform, MDN

Syntax:

Default value: all

.transition-property(<propertyname> | all | none)

Tips and tricks:

And also properties inside transition-property definition are automatically prefixed, if it is needed.
W3C property value is appending all prefixed values.
Why? Some browsers support W3C unprefixed properties, but values must be sometimes prefixed. Let's consider this example:

div {
-webkit-transition: -webkit-filter .3s ease;
-moz-transition: -moz-filter .3s ease;
-o-transition: filter .3s ease;

// There is a problem! Webkit needs -webkit-filter property
transition: filter .3s ease;
}

Example:

div {
 .transition-property(transform);
}

// Result
div {
 -webkit-transition-property: -webkit-transform;
 -moz-transition-property: -moz-transform;
 -o-transition-property: -o-transform;
 transition-property: -webkit-transform,-moz-transform,-o-transform,transform;
}

• transition-timing-function

Summary:

The CSS transition-timing-function property is used to describe how the intermediate values of the CSS properties being affected by a transition effect are calculated. This in essence lets you establish an acceleration curve, so that the speed of the transition can vary over its duration.

Resources: WebPlatform, MDN

Syntax:

Default value: ease

.transition-timing-function(<timing-function>, ...)

Example:

div {
 .transition-timing-function(cubic-bezier(0,0,1,1), ease);
}

// Result
div {
 -webkit-transition-timing-function: cubic-bezier(0, 0, 1, 1), ease;
 -moz-transition-timing-function: cubic-bezier(0, 0, 1, 1), ease;
 -o-transition-timing-function: cubic-bezier(0, 0, 1, 1), ease;
 transition-timing-function: cubic-bezier(0, 0, 1, 1), ease;
}

• translate

Summary:

Specifies a 2D translation by the vector [tx, ty]. If ty isn't specified, its value is assumed to be zero.

Resources: MDN

Syntax:

Default value: 0

.translate(<tx>[, <ty>])

Tips and tricks:

If you omit units, translate adds px automatically.

Example:

div {
 .translate(200);
}

// Result
div {
 -webkit-transform: translate(200px);
 -moz-transform: translate(200px);
 -ms-transform: translate(200px);
 -o-transform: translate(200px);
 transform: translate(200px);
}

• translate3d

Summary:

The translate3d() CSS function moves the position of the element in the 3D space.

Resources: MDN

Syntax:

Default value: 0

.translate3d(<tx>, <ty>, <tz>)

Tips and tricks:

If you omit units, translate3d adds px automatically.

Example:

div {
 .translate3d(20, 30, 10);
}

// Result
div {
 -webkit-transform: translate3d(20px, 30px, 10px);
 -moz-transform: translate3d(20px, 30px, 10px);
 -ms-transform: translate3d(20px, 30px, 10px);
 -o-transform: translate3d(20px, 30px, 10px);
 transform: translate3d(20px, 30px, 10px);
}

• translateX

Summary:

Translates the element by the given amount along the X axis.

Resources: MDN

Syntax:

Default value: 0

.translateX(<tx>)

Tips and tricks:

If you omit units, translateX adds px automatically.

Example:

div {
 .translateX(20);
}

// Result
div {
 -webkit-transform: translateX(20px);
 -moz-transform: translateX(20px);
 -ms-transform: translateX(20px);
 -o-transform: translateX(20px);
 transform: translateX(20px);
}

• translateY

Summary:

Translates the element by the given amount along the Y axis.

Resources: MDN

Syntax:

Default value: 0

.translateY(<ty>)

Tips and tricks:

If you omit units, translateY adds px automatically.

Example:

div {
 .translateY(20);
}

// Result
div {
 -webkit-transform: translateY(20px);
 -moz-transform: translateY(20px);
 -ms-transform: translateY(20px);
 -o-transform: translateY(20px);
 transform: translateY(20px);
}

• translateZ

Summary:

Translates the element by the given amount along the Z axis.

Resources: MDN

Syntax:

Default value: 0

.translateZ(<ty>)

Tips and tricks:

If you omit units, translateZ adds px automatically.

Example:

div {
 .translateZ(20);
}

// Result
div {
 -webkit-transform: translateZ(20px);
 -moz-transform: translateZ(20px);
 -ms-transform: translateZ(20px);
 -o-transform: translateZ(20px);
 transform: translateZ(20px);
}

• user-select

Summary:

Controls the appearance (only) of selection.

Resources: MDN

Syntax:

Default value: auto

.user-select(none | text | all | element)

Example:

div {
 .user-select(none);
}

// Result
div {
 -webkit-user-select: none;
 -moz-user-select: none;
 -ms-user-select: none;
 user-select: none;
}

Big Thanks to:

• Jan Kuca (help us with lesshat-devstack)
• MOZILLA DEVELOPER NETWORK (almost all summary are from MDN)
• CSS-Tricks (their CSS almanac is great resource)
• Angular UI router (example of good github profile)
• Marek Hrabe (for coding lesshat.com)
• Jan Vu Nam (for design lesshat.com and lesshat book icon)