art/_sass/layout/_menu.scss

///
/// Forty by HTML5 UP
/// html5up.net | @ajlkn
/// Free for personal and commercial use under the CCA 3.0 license (html5up.net/license)
///

/* Menu */

	#menu {
		@include vendor('transition', (
			'transform #{_duration(menu)} ease',
			'opacity #{_duration(menu)} ease',
			'visibility #{_duration(menu)}'
		));
		@include vendor('align-items', 'center');
		@include vendor('display', 'flex');
		@include vendor('justify-content', 'center');
		@include vendor('pointer-events', 'none');
		background: transparentize(_palette(bg), 0.1);
		box-shadow: none;
		height: 100%;
		left: 0;
		opacity: 0;
		overflow: hidden;
		padding: 3em 2em;
		position: fixed;
		top: 0;
		visibility: hidden;
		width: 100%;
		z-index: _misc(z-index-base) + 2;

		.inner {
			@include vendor('transition', (
				'transform #{_duration(menu)} ease-out',
				'opacity #{_duration(menu)} ease',
				'visibility #{_duration(menu)}'
			));
			@include vendor('transform', 'rotateX(20deg)');
			-webkit-overflow-scrolling: touch;
			max-width: 100%;
			max-height: 100vh;
			opacity: 0;
			overflow: auto;
			text-align: center;
			visibility: hidden;
			width: 18em;

			> :first-child {
				margin-top: _size(element-margin);
			}

			> :last-child {
				margin-bottom: (_size(element-margin) * 1.5);
			}
		}

		ul {
			margin: 0 0 (_size(element-margin) * 0.5) 0;

			&.links {
				list-style: none;
				padding: 0;

				> li {
					padding: 0;

					> a:not(.button) {
						border: 0;
						border-top: solid 1px _palette(border);
						display: block;
						font-size: 0.8em;
						font-weight: _font(weight-bold);
						letter-spacing: _font(letter-spacing-alt);
						line-height: 4em;
						text-decoration: none;
						text-transform: uppercase;
					}

					> .button {
						display: block;
						margin: 0.5em 0 0 0;
					}

					&:first-child {
						> a:not(.button) {
							border-top: 0 !important;
						}
					}
				}
			}
		}

		.close {
			@include vendor('transition', 'color #{_duration(transition)} ease-in-out');
			-webkit-tap-highlight-color: rgba(0,0,0,0);
			border: 0;
			cursor: pointer;
			display: block;
			height: 4em;
			line-height: 4em;
			overflow: hidden;
			padding-right: 1.25em;
			position: absolute;
			right: 0;
			text-align: right;
			text-indent: 8em;
			top: 0;
			vertical-align: middle;
			white-space: nowrap;
			width: 8em;

			&:before, &:after {
				@include vendor('transition', 'opacity #{_duration(transition)} ease-in-out');
				background-position: center;
				background-repeat: no-repeat;
				content: '';
				display: block;
				height: 4em;
				position: absolute;
				right: 0;
				top: 0;
				width: 4em;
			}

			&:before {
				background-image: svg-url('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20px" height="20px" viewBox="0 0 20 20" zoomAndPan="disable"><style>line { stroke: #{_palette(fg-bold)}; stroke-width: 2; }</style><line x1="0" y1="0" x2="20" y2="20" /><line x1="20" y1="0" x2="0" y2="20" /></svg>');
			}

			&:after {
				background-image: svg-url('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20px" height="20px" viewBox="0 0 20 20" zoomAndPan="disable"><style>line { stroke: #{_palette(highlight)}; stroke-width: 2; }</style><line x1="0" y1="0" x2="20" y2="20" /><line x1="20" y1="0" x2="0" y2="20" /></svg>');
				opacity: 0;
			}

			&:hover, &:active {
				&:after {
					opacity: 1;
				}
			}
		}
	}

	body.is-ie {
		#menu {
			background: transparentize(_palette(bg-alt), 0.025);
		}
	}

	body.is-menu-visible {
	    #wrapper {
		-webkit-backface-visibility: hidden;
		-webkit-perspective: 1000;
		-webkit-transform: translate3d(0,0,0);
		-webkit-transform: translateZ(0);
		backface-visibility: hidden;
		perspective: 1000;
		transform: translate3d(0,0,0);
		transform: translateZ(0);
		}

		#menu {
			@include vendor('pointer-events', 'auto');
			opacity: 1;
			visibility: visible;

			.inner {
				@include vendor('transform', 'none');
				opacity: 1;
				visibility: visible;
			}
		}
	}