4 Columns - Fixed, Fluid & Padded Grid

01_grid.less

.grid {
	margin: 0 auto;
	width: 960px;
	
	._01 {
		width: 960px / 4 * 1 - 2 * 10px;
	}
	
	._02 {
		width: 960px / 4 * 2 - 2 * 10px;
	}
	
	._03 {
		width: 960px / 4 * 3 - 2 * 10px;
	}
	
	._04 {
		width: 960px / 4 * 4 - 2 * 10px;
	}
	
	._01, ._02, ._03, ._04 {
		display: inline;
		float: left;
		margin: 0 10px;
		/*position: relative;*/
		
		&.alpha {
			margin-left: 0;
		}
		
		&.omega {
			margin-right: 0;
		}
	}
}

//@import '02_fluid.less';
//@import '03_padded.less'

02_fluid.less

.grid {
	width: 96%;

	._01 {
		width: 100% / 4 * 1 - 2 * 1%;
	}
	
	._02 {
		width: 100% / 4 * 2 - 2 * 1%;
	}
	
	._03 {
		width: 100% / 4 * 3 - 2 * 1%;
	}
	
	._04 {
		width: 100% / 4 * 4 - 2 * 1%;
	}
	
	._01, ._02, ._03, ._04 {
		margin: 0 1%;

		> ._01 {
			width: 25% - 2 * 1%;

			&.alpha, &.omega {
				width: 25% - 1 * 1%;
			}
		}

		> ._02 {
			width: 50% - 2 * 1%;

			&.alpha, &.omega {
				width: 50% - 1 * 1%;
			}
		}

		> ._03 {
			width: 75% - 2 * 1%;

			&.alpha, &.omega {
				width: 75% - 1 * 1%;
			}
		}

		> ._04 {
			width: 100%;
		}
	}
}

03_padded.less

.grid {
	._01 {
		width: 100% / 4 * 1;
	}

	._02 {
		width: 100% / 4 * 2;
	}

	._03 {
		width: 100% / 4 * 3;
	}

	._04 {
		width: 100% / 4 * 4;
	}

	._01, ._02, ._03, ._04 {
		margin: 0;
		padding: 0 10px;
		-moz-box-sizing: border-box;
		
		&.alpha {
			padding-left: 0;
		}

		&.omega {
			padding-right: 0;
		}
	}
}