szurubooru/public_html/css/post-list.css

.post-list {
	text-align: center;
}

.post-list form button {
	margin-left: 0.25em;
}

.post-list .search {
	margin-bottom: 1em;
	text-align: left;
}
.post-list .search input {
	max-width: 20em;
}
.post-list .search .mass-tag-wrapper {
	float: right;
}
.post-list .search .mass-tag-wrapper p {
	display: inline;
	margin-right: 1em;
}

.post-list ul {
	display: flex;
	justify-content: center;
	align-content: center;
	flex-wrap: wrap;
	list-style-type: none;
	padding: 0;
	margin: 0;
}
.post-list ul.posts .post-small {
	margin: 0;
	padding: 0;
}

.post-small {
	position: relative;
}
.post-small a {
	display: block;
	margin: 0.2em;
	border: 1px solid #999;
	z-index: 1;
	position: relative;
}
.post-small img {
	display: block;
	border: 0;
	background: white;
}

.post-small a:focus,
.post-small a:hover {
	background: #64C2ED;
	border-color: #64C2ED;
	box-shadow: 0 0 0 2px #64C2ED;
	outline: 0;
}

.post-small a:focus img,
.post-small a:hover img {
	opacity: .8 !important;
}

.post-small a .info {
	display: none;
	text-align: center;
	position: absolute;
	bottom: 0;
	left: 0;
	right: 0;
	background: #64C2ED;
	color: black;
}
.post-small a .info ul {
	list-style-type: none;
	padding: 0;
	margin: 0;
}
.post-small a .info li {
	display: inline-block;
	margin: 0.1em 0.5em;
	padding: 0;
}
.post-small a:focus .info,
.post-small a:hover .info {
	display: block;
}

.post-small:not(.post-type-image) a::before {
	display: block;
	content: '';
	z-index: 2;
	position: absolute;
	top: 0;
	right: 0;
	width: 0;
	height: 0;
	border-top: 50px solid red;
	border-left: 50px solid transparent;
}

.post-small:not(.post-type-image) a::after {
	display: block;
	content: '...';
	z-index: 3;
	position: absolute;
	top: -35px; /* 50 * sqrt(2) / 2 */
	right: -35px;
	width: 71px; /* 50 * sqrt(2) */
	height: 71px;
	line-height: 122px; /* 71 * 2 - 11 (font-size) - padding */
	transform: rotate(45deg);

	color: white;
	font-size: 15px;
}
.post-small.post-type-youtube a::after {
	font-size: 13px;
	content: 'youtube';
}
.post-small.post-type-video a::after {
	content: 'video';
}
.post-small.post-type-flash a::after {
	content: 'flash';
}

.post-small .action {
	display: none;
	position: absolute;
	z-index: 3;
	left: 0;
	right: 0;
	top: 50%;
	bottom: 0;
	pointer-events: none;
}

.post-small .action button {
	padding: 0.5em 1em;
	height: 1em;
	line-height: 1em;
	display: block;
	margin: -1em auto 0 auto;
	box-sizing: content-box;
	opacity: .7;
	box-shadow: none;
	pointer-events: auto;
}
.post-small .action button:focus {
	box-shadow: 0 0 0 2px #64C2ED inset !important;
}

.tagged .action button,
.untagged .action button {
	border: 1px solid black;
	font-weight: bold;
	text-shadow: none;
}
.untagged .action button::before {
	background: red;
}
.untagged .action button {
	color: white;
}
.tagged .action button::before {
	background: lime;
}
.tagged .action button {
	color: black;
}