.element{
// properties
width: 100%;
height: 50px;
// mixins
.verticalGradient(#ffffff, #000000);
.boxSizing();
// modifiers
&.small{
width: 50%;
height: 25px;
}
&.disabled{
background: #f5f5f5;
}
//pseudo-class
&:hover{}
&:focus{}
&:active{}
// pseudo-elements
&:after{}
&:before{}
&:first-child{}
&:last-child{}
// children's
header{}
footer{}
.content{}
}