:root {
	--bg: #f4f7fb;
	--card: #ffffff;
	--ink: #16213a;
	--ink-soft: #5b6b86;
	--line: #e6ecf5;
	--brand: #1f6feb;
	--brand-2: #13c2c2;
	--danger: #d4380d;
	--warn: #d48806;
	--ok: #389e0d;
	--shadow: 0 10px 30px rgba(22, 33, 58, 0.08);
	--radius: 16px;
}

* {
	box-sizing: border-box;
}

html,
body {
	margin: 0;
	padding: 0;
}

body {
	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
		"Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
	background: var(--bg);
	color: var(--ink);
	line-height: 1.6;
	-webkit-font-smoothing: antialiased;
}

a {
	color: inherit;
}

/* ---------- Site header ---------- */
.site-header {
	background: #0f1f3d;
	color: #fff;
	position: sticky;
	top: 0;
	z-index: 10;
	box-shadow: 0 2px 12px rgba(15, 31, 61, 0.18);
}

.nav-inner {
	max-width: 1040px;
	margin: 0 auto;
	padding: 0 20px;
	height: 60px;
	display: flex;
	align-items: center;
	justify-content: space-between;
}

.logo {
	font-size: 20px;
	font-weight: 800;
	letter-spacing: 1px;
	text-decoration: none;
	color: #fff;
}

.logo span {
	color: var(--brand-2);
}

.nav-links {
	display: flex;
	gap: 6px;
}

.nav-links a {
	text-decoration: none;
	color: #c7d2e6;
	font-size: 15px;
	font-weight: 600;
	padding: 8px 14px;
	border-radius: 999px;
	transition: background 0.12s ease, color 0.12s ease;
}

.nav-links a:hover {
	background: rgba(255, 255, 255, 0.1);
	color: #fff;
}

.nav-links a.active {
	background: var(--brand);
	color: #fff;
}

/* ---------- Hero ---------- */
.hero {
	background: linear-gradient(135deg, #1f6feb 0%, #13c2c2 100%);
	color: #fff;
	padding: 52px 20px 64px;
	position: relative;
	overflow: hidden;
}

.hero::after {
	content: "";
	position: absolute;
	inset: 0;
	background-image: radial-gradient(
			circle at 20% 20%,
			rgba(255, 255, 255, 0.18),
			transparent 40%
		),
		radial-gradient(circle at 85% 10%, rgba(255, 255, 255, 0.12), transparent 35%);
	pointer-events: none;
}

.hero-inner {
	max-width: 880px;
	margin: 0 auto;
	position: relative;
	z-index: 1;
}

.hero h1 {
	margin: 0;
	font-size: 32px;
	font-weight: 700;
	letter-spacing: 0.3px;
}

.tagline {
	margin: 8px 0 0;
	opacity: 0.92;
	font-size: 15px;
}

.hero-compact {
	padding: 36px 20px 44px;
}

/* ---------- Search ---------- */
.search-box {
	display: flex;
	gap: 10px;
	background: #fff;
	padding: 8px;
	border-radius: 999px;
	box-shadow: var(--shadow);
	margin-top: 22px;
	max-width: 640px;
}

.search-box input {
	flex: 1;
	border: none;
	outline: none;
	padding: 12px 18px;
	font-size: 16px;
	border-radius: 999px;
	color: var(--ink);
	background: transparent;
}

.search-box button {
	border: none;
	background: linear-gradient(135deg, #1f6feb, #13c2c2);
	color: #fff;
	font-weight: 600;
	padding: 12px 26px;
	border-radius: 999px;
	cursor: pointer;
	font-size: 15px;
	transition: transform 0.12s ease, opacity 0.12s ease;
}

.search-box button:hover {
	transform: translateY(-1px);
	opacity: 0.94;
}

.search-box button:active {
	transform: translateY(0);
}

.examples {
	margin-top: 16px;
	display: flex;
	flex-wrap: wrap;
	gap: 8px;
}

.chip {
	background: rgba(255, 255, 255, 0.18);
	color: #fff;
	border: 1px solid rgba(255, 255, 255, 0.35);
	padding: 6px 14px;
	border-radius: 999px;
	font-size: 13px;
	cursor: pointer;
	transition: background 0.12s ease;
}

.chip:hover {
	background: rgba(255, 255, 255, 0.32);
}

.chip.label {
	cursor: default;
	background: transparent;
	border-color: transparent;
	padding-right: 4px;
}

.chip.label:hover {
	background: transparent;
}

/* ---------- Layout ---------- */
.container {
	max-width: 1040px;
	margin: 32px auto 0;
	padding: 0 20px 48px;
}

.container-narrow {
	max-width: 760px;
}

.section-title {
	font-size: 20px;
	margin: 0 0 16px;
}

/* ---------- Featured (1 row, 3 cards) ---------- */
.featured-grid {
	display: grid;
	grid-template-columns: repeat(3, 1fr);
	gap: 16px;
}

@media (max-width: 760px) {
	.featured-grid {
		grid-template-columns: 1fr;
	}
}

.featured {
	margin-bottom: 36px;
}

/* ---------- Results grid ---------- */
.results-grid {
	display: grid;
	grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
	gap: 18px;
}

/* ---------- Card ---------- */
.card {
	background: var(--card);
	border: 1px solid var(--line);
	border-radius: var(--radius);
	padding: 20px 20px 18px;
	box-shadow: var(--shadow);
	transition: transform 0.14s ease, box-shadow 0.14s ease;
	display: flex;
	flex-direction: column;
	gap: 12px;
}

.card:hover {
	transform: translateY(-3px);
	box-shadow: 0 16px 40px rgba(22, 33, 58, 0.12);
}

.card-head {
	display: flex;
	justify-content: space-between;
	align-items: flex-start;
	gap: 10px;
}

.card-title {
	margin: 0;
	font-size: 19px;
	font-weight: 700;
}

.card-sub {
	margin: 2px 0 0;
	font-size: 13px;
	color: var(--ink-soft);
}

.cas-badge {
	flex-shrink: 0;
	background: #eef4ff;
	color: var(--brand);
	font-weight: 700;
	font-size: 13px;
	padding: 5px 10px;
	border-radius: 8px;
	font-family: "SFMono-Regular", Consolas, monospace;
	white-space: nowrap;
}

.formula {
	font-family: "SFMono-Regular", Consolas, monospace;
	font-size: 22px;
	font-weight: 700;
	color: var(--ink);
}

.meta {
	display: grid;
	grid-template-columns: auto 1fr;
	gap: 4px 12px;
	font-size: 13.5px;
	margin: 0;
}

.meta dt {
	color: var(--ink-soft);
	white-space: nowrap;
}

.meta dd {
	margin: 0;
	color: var(--ink);
}

.hazard {
	display: inline-block;
	font-size: 12.5px;
	font-weight: 600;
	padding: 4px 10px;
	border-radius: 999px;
	align-self: flex-start;
}

.hz-danger {
	background: #fff1ec;
	color: var(--danger);
}
.hz-warn {
	background: #fff8e6;
	color: var(--warn);
}
.hz-ok {
	background: #f6ffed;
	color: var(--ok);
}

.aliases {
	font-size: 12.5px;
	color: var(--ink-soft);
}

.pubchem {
	display: inline-flex;
	align-items: center;
	gap: 6px;
	margin-top: auto;
	font-size: 13px;
	color: var(--brand);
	text-decoration: none;
	font-weight: 600;
}

.pubchem:hover {
	text-decoration: underline;
}

/* ---------- States ---------- */
.hidden {
	display: none !important;
}

.status {
	margin: 8px 4px 20px;
	color: var(--ink-soft);
	font-size: 14px;
	min-height: 20px;
}

.empty,
.error {
	text-align: center;
	padding: 60px 20px;
	color: var(--ink-soft);
}

.empty .big,
.error .big {
	font-size: 40px;
	margin-bottom: 12px;
}

.error {
	color: var(--danger);
}

/* ---------- About ---------- */
.about {
	background: #fff;
	border: 1px solid var(--line);
	border-radius: var(--radius);
	padding: 32px;
	box-shadow: var(--shadow);
}

.about h1 {
	margin-top: 0;
}

.about code {
	background: #eef2f8;
	padding: 2px 6px;
	border-radius: 6px;
	font-size: 0.9em;
}

/* ---------- Footer ---------- */
.footer {
	text-align: center;
	padding: 24px 20px 40px;
	color: var(--ink-soft);
	font-size: 13px;
}

@media (max-width: 520px) {
	.hero {
		padding: 36px 16px 48px;
	}
	.hero h1 {
		font-size: 25px;
	}
	.search-box {
		flex-direction: column;
		border-radius: var(--radius);
	}
	.search-box input,
	.search-box button {
		border-radius: 12px;
	}
	.results-grid {
		grid-template-columns: 1fr;
	}
	.about {
		padding: 22px;
	}
}