The .lib-clearfix() mixin is a modern solution for healing container`s height which have floated elements. Also its applying prevents top-margins from collapsing.
 Container with floated child elements without .lib-clearfix()
 Container with floated child elements with .lib-clearfix()
.example-clearfix-container-1 {
    border: 1px solid #f00;
}
.example-clearfix-container-2 {
    .lib-clearfix();
    border: 1px solid #0f0;
}
.example-clearfix-item.left {
    float: left;
}
.example-clearfix-item.right {
    float: right;
}  The .lib-css() mixin is used to set any css property if there is a value passed to it by a variable. Also .lib-css() can add -ms-, -webkit- and -moz- prefixes if needed.
  If the variable is set to false, the .lib-css() mixin will add nothing to the code.
.example-css-container {
    .lib-css(padding, @indent__base);
    .lib-css(background, @secondary__color);
}
.example-css-container-2 {
    .lib-css(background, false);
}.example-rotate {
    background: #f00;
    position: absolute;
    height: 20px;
    width: 40px;
    .lib-rotate(
        @_rotation: 45deg;
    );
}  The .lib-input-placeholder() mixin is used to change placeholder font-color and font-weight.
.example-placeholder {
    .lib-input-placeholder(#808080, bold);
}
    | Mixin variable | Default value | Allowed values | Comment | 
|---|---|---|---|
| @_input-placeholder-color | @form-element-input-placeholder__color | '' | false | value | Input placeholder color | 
| @_input-placeholder-font-weight | @form-element-input__font-weight | '' | false | value | Input placeholder font-weight | 
  The .lib-background-gradient() mixin is used for applying custom css3 gradient.
.example-background-gradient-1 {
    .lib-background-gradient(
        @_background-gradient: true,
        @_background-gradient-direction: vertical,
        @_background-gradient-color-start: #cff,
        @_background-gradient-color-end: #ccf
    );
}
.example-background-gradient-2 {
    .lib-background-gradient(
        @_background-gradient: true,
        @_background-gradient-direction: horizontal,
        @_background-gradient-color-start: #cff,
        @_background-gradient-color-end: #ccf
    );
}
.example-background-gradient-3-wrapper {
    background: #ffc;
    padding: 10px;
}
.example-background-gradient-3 {
    .lib-background-gradient(
        @_background-gradient: true,
        @_background-gradient-direction: horizontal,
        @_background-gradient-color-start: rgba(255,255,255,0),
        @_background-gradient-color-end: #ccf,
        @_background-gradient-color-position: false
    );
}
    | Mixin variable | Default value | Allowed values | Comment | 
|---|---|---|---|
| @_background-gradient | false | '' | false | true | If set to 'true' the element has gradient background | 
| @_background-gradient-direction | '' | '' | horizontal | vertical | Gradient direction (horizontal or vertical) | 
| @_background-gradient-color-start | '' | '' | false | value | Gradient start color (any css color) | 
| @_background-gradient-color-end | '' | '' | false | value | Gradient end color (any css color) | 
| @_background-gradient-color-position | false | '' | false | true | Sets the background-color fallback property. When set to 'false', the background-color property will be set to @_background-gradient-color-end. When set to 'true', the background-color property will be set to @_background-gradient-color-start |