/* ==========================================================================
   SAIL Lab — Safe AI and Robot Learning Lab @ Shanghai Jiao Tong University
   Stylesheet for the lab website (top-navigation layout).
   Visual language inherited from the original personal page:
     -- brand navy  #0A2245 (header bar)
     -- accent      #bd1eb4 (venue tags / highlights)
     -- links       #0366d6
   ========================================================================== */

:root {
	--brand:      #0A2245;  /* deep navy (header) */
	--brand-2:    #16335f;  /* slightly lighter navy for hover */
	--accent:     #bd1eb4;  /* original accent */
	--accent-hov: #ea4aaa;  /* original accent hover */
	--metric:     #FF0000;  /* IF / oral marks */
	--link:       #0366d6;  /* link blue */
	--bg-soft:    #f6f8fa;  /* light gray panel */
	--border:     #e1e4e8;  /* hairline borders */
	--text:       #24292e;
	--muted:      #586069;
	--maxw:       1100px;
}

* {
	box-sizing: border-box;
}

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

body {
	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
		Ubuntu, Cantarell, "Fira Sans", "Droid Sans", "Helvetica Neue",
		Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji",
		"Segoe UI Symbol";
	font-size: 16px;
	color: var(--text);
	background: #fff;
	line-height: 1.5;
}

a {
	color: var(--link);
	text-decoration: none;
}
a:hover {
	color: var(--accent-hov);
}
a[target="_blank"]::after {
	content: "";
}
/* subtle marker for external links */
img.icon {
	width: 18px;
	height: 18px;
	margin: 0 8px 0 0;
	vertical-align: middle;
}

/* --------------------------------------------------------------------------
   Header: brand bar + horizontal navigation (sticky)
   -------------------------------------------------------------------------- */
.site-header {
	position: sticky;
	top: 0;
	z-index: 100;
}

.brand-bar {
	background: var(--brand);
	color: #fff;
}

.brand-inner {
	max-width: var(--maxw);
	margin: 0 auto;
	display: flex;
	align-items: center;
	gap: 16px;
	padding: 8px 24px;
}

.brand-seal {
	display: inline-flex;
	align-items: center;
	line-height: 0;
}
.brand-seal img {
	height: 52px;
	width: auto;
	margin: 0;
	padding: 0;
	border-radius: 0;
}

.brand-title {
	display: flex;
	flex-direction: column;
	justify-content: center;
	line-height: 1.15;
	border-left: 1px solid rgba(255, 255, 255, 0.35);
	padding-left: 16px;
}
.brand-title a {
	color: #fff;
	font-size: 25px;
	font-weight: 700;
	letter-spacing: 0.3px;
}
.brand-title a:hover {
	color: #fff;
	opacity: 0.92;
}
.brand-sub {
	font-size: 12.5px;
	color: rgba(255, 255, 255, 0.75);
	font-weight: 400;
	letter-spacing: 0.2px;
}

.brand-links {
	margin-left: auto;
	display: flex;
	align-items: center;
	gap: 14px;
	font-size: 14px;
	white-space: nowrap;
}
.brand-links a {
	color: rgba(255, 255, 255, 0.85);
}
.brand-links a:hover {
	color: #fff;
}
.brand-links svg {
	width: 20px;
	height: 20px;
	fill: rgba(255, 255, 255, 0.92);
	display: inline-block;
	vertical-align: middle;
}
.brand-links a:hover svg {
	fill: #fff;
}

#nav-toggle {
	display: none;             /* hamburger — visible only on small screens */
	background: none;
	border: 1px solid rgba(255, 255, 255, 0.4);
	border-radius: 6px;
	color: #fff;
	font-size: 22px;
	line-height: 1;
	padding: 6px 10px;
	cursor: pointer;
	margin-left: auto;
}
#nav-toggle:hover {
	background: var(--brand-2);
}

.site-nav {
	background: #fff;
	border-bottom: 1px solid var(--border);
	box-shadow: 0 1px 3px rgba(10, 34, 69, 0.06);
}

.nav-inner {
	max-width: var(--maxw);
	margin: 0 auto;
	padding: 0 16px;
}

.nav-list {
	list-style: none;
	margin: 0;
	padding: 0;
	display: flex;
	flex-wrap: wrap;
}

.nav-item a {
	display: inline-block;
	padding: 12px 15px 10px 15px;
	margin: 0 1px;
	font-size: 15.5px;
	color: #24292e;
	border-bottom: 3px solid transparent;
}
.nav-item a:hover {
	color: var(--accent-hov);
}
.nav-item.current a {
	color: var(--brand);
	font-weight: 600;
	border-bottom-color: var(--brand);
}

/* --------------------------------------------------------------------------
   Page body / footer
   -------------------------------------------------------------------------- */
.page {
	max-width: var(--maxw);
	margin: 0 auto;
	padding: 28px 28px 44px 28px;
	min-height: calc(100vh - 210px);
}

.site-footer {
	background: #fff;
	border-top: 1px solid var(--border);
}
.footer-inner {
	max-width: var(--maxw);
	margin: 0 auto;
	padding: 20px 28px 26px 28px;
	font-size: 13.5px;
	color: #9099a3;
	text-align: center;
	line-height: 1.8;
}
.footer-inner a {
	color: #6a7683;
}
.footer-inner a:hover {
	color: var(--accent-hov);
}

/* --------------------------------------------------------------------------
   Typography (kept close to the original jemdoc look)
   -------------------------------------------------------------------------- */
h1, h2, h3, h4 {
	font-weight: 400;
	line-height: 1.25;
}

h1 {
	font-size: 32px;
	margin: 0.4em 0 0.5em 0;
	padding-bottom: 0.2em;
	border-bottom: 1px solid var(--border);
}
h1:first-child {
	margin-top: 0;
}

h2 {
	font-size: 24px;
	padding-top: 0.8em;
	margin: 0 0 16px 0;
	padding-bottom: 0.2em;
	border-bottom: 1px solid var(--border);
}

h3 {
	font-size: 20px;
	margin: 0 0 8px 0;
	border-bottom: none;
}

h4 {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	font-size: 16px;
	margin: 8px 0;
	font-weight: 400;
	row-gap: 4px;
}
h4 img.icon {
	width: 18px;
	height: 18px;
	margin-right: 8px;
	position: relative;
	top: 0;
}
h4 a {
	text-decoration: none;
	color: inherit;
	margin-right: 4px;
}
h4 .sep {
	margin: 0 14px;
	color: #cfd4da;
}

p {
	font-size: 16px;
	line-height: 1.6;
	margin: 0 0 0.8em 0;
	text-align: justify;
}

ul, ol {
	margin: 0.2em 0 0.8em 0;
	padding-left: 1.6em;
}
li {
	margin-bottom: 0.15em;
}
ul { list-style: square; }
.page li p { margin-bottom: 0.35em; }

em { font-style: italic; }
strong { font-weight: 600; }

img {
	border-radius: 10px;
	margin: 0 20px 10px 0;
	max-width: 100%;
}

/* --------------------------------------------------------------------------
   Generic building blocks
   -------------------------------------------------------------------------- */
.lead {
	font-size: 17px;
	color: #3c3f44;
}

.panel {
	background: var(--bg-soft);
	border: 1px solid var(--border);
	border-radius: 10px;
	padding: 14px 18px;
	margin: 12px 0 18px 0;
}

.panel-accent {
	border-left: 4px solid var(--accent);
	background: #fdf3fc;
}

.hl {
	color: var(--accent);
	font-weight: 600;
}

.tag {
	display: inline-block;
	background: var(--accent);
	color: #fff;
	border-radius: 4px;
	font-size: 12.5px;
	font-weight: 600;
	padding: 1px 8px;
	margin-right: 8px;
	vertical-align: 2px;
	white-space: nowrap;
}

.chip {
	display: inline-block;
	background: #eef1f6;
	border: 1px solid var(--border);
	color: var(--brand);
	border-radius: 999px;
	font-size: 14px;
	font-weight: 500;
	padding: 4px 14px;
	margin: 2px 6px 6px 0;
}

.btn {
	display: inline-block;
	background: var(--accent);
	color: #fff !important;
	border-radius: 6px;
	font-size: 15.5px;
	font-weight: 600;
	padding: 9px 20px;
	margin-top: 4px;
}
.btn:hover {
	background: var(--accent-hov);
}
.btn.navy {
	background: var(--brand);
}
.btn.navy:hover {
	background: var(--brand-2);
}

.muted { color: var(--muted); }
.metric { color: var(--metric); }
.venue { color: var(--accent); }

/* welcome / hero text on the homepage */
.welcome h1 {
	font-size: 34px;
	margin-top: 0.2em;
}
.welcome .tagline {
	font-size: 18px;
	color: var(--muted);
	margin-bottom: 14px;
}

/* --------------------------------------------------------------------------
   Paper / preprint entries (venue tag on the left, info on the right)
   -------------------------------------------------------------------------- */
.pub-row {
	display: flex;
	align-items: flex-start;
	margin: 0 0 18px 0;
}
.pub-row .paper-tag {
	background: var(--accent);
	color: #fff;
	padding: 4px 8px;
	border-radius: 4px;
	font-weight: 600;
	font-size: 12.5px;
	line-height: 1.25;
	display: inline-flex;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	text-align: center;
	flex: 0 0 88px;
	min-height: 34px;
	margin-right: 16px;
	word-wrap: break-word;
	hyphens: auto;
}
.pub-main {
	flex: 1;
	min-width: 0;
}
.pub-main p { margin: 0 0 4px 0; text-align: left; }

.paper-tag.plain {
	background: #eef1f6;
	color: var(--brand);
	border: 1px solid var(--border);
}

/* product / platform cards (used on the homepage) */
.card-grid {
	display: flex;
	flex-wrap: wrap;
	gap: 16px;
	margin: 6px 0 16px 0;
}
.card {
	flex: 1 1 250px;
	border: 1px solid var(--border);
	border-top: 3px solid var(--accent);
	border-radius: 10px;
	padding: 16px 18px;
	background: #fff;
	display: flex;
	flex-direction: column;
	transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.card:hover {
	box-shadow: 0 4px 14px rgba(0, 0, 0, 0.1);
	transform: translateY(-2px);
}
.card h3 {
	margin: 0 0 6px 0;
	padding: 0;
	font-size: 19px;
	font-weight: 600;
}
.card h3 a { color: var(--link); }
.card p {
	font-size: 15px;
	line-height: 1.5;
	margin: 0 0 12px 0;
	text-align: left;
	color: #444;
	flex-grow: 1;
}
.card .more {
	font-size: 15px;
	font-weight: 600;
	color: var(--accent);
	align-self: flex-start;
}
.card .more:hover { color: var(--accent-hov); }

/* project rows (image left + text right) */
.proj {
	display: flex;
	align-items: flex-start;
	gap: 22px;
	margin: 8px 0 26px 0;
}
.proj img {
	width: 300px;
	max-width: 100%;
	flex: 0 0 auto;
	margin: 0;
	border: 1px solid var(--border);
}
.proj h3 {
	font-weight: 600;
	margin-top: 0;
	padding-top: 0;
	font-size: 19px;
}
.proj p { text-align: left; }
.proj .links { font-size: 15.5px; }

/* --------------------------------------------------------------------------
   People (group page)
   -------------------------------------------------------------------------- */
.person-grid {
	display: grid;
	grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
	gap: 14px;
	margin: 10px 0 22px 0;
}
.person-card {
	background: #fff;
	border: 1px solid var(--border);
	border-radius: 10px;
	padding: 16px 14px 12px 14px;
	text-align: center;
}
.person-card .avatar {
	width: 74px;
	height: 74px;
	margin: 0 auto 10px auto;
	border-radius: 50%;
	background: var(--brand);
	color: #fff;
	font-size: 26px;
	font-weight: 600;
	display: flex;
	align-items: center;
	justify-content: center;
	letter-spacing: 0.5px;
}
.person-card .avatar.accent  { background: var(--accent); }
.person-card .avatar.teal    { background: #0d7c8f; }
.person-card .avatar.green   { background: #2e7d32; }
.person-card .avatar.orange  { background: #c05621; }
.person-card .avatar.purple  { background: #6a3fb5; }
.person-card .p-name {
	font-size: 17px;
	font-weight: 600;
	color: var(--text);
}
.person-card .p-affil {
	font-size: 13.5px;
	color: var(--muted);
	margin-top: 2px;
	line-height: 1.4;
}
.person-card .avatar a {
	color: #fff;
	text-decoration: none;
}
.person-card .avatar a:hover {
	opacity: 0.85;
}

.pi-row {
	display: flex;
	align-items: flex-start;
	gap: 22px;
	margin: 4px 0 18px 0;
}
.pi-row img.pi-photo {
	width: 150px;
	height: auto;
	flex: 0 0 auto;
	margin: 0;
	border: 1px solid var(--border);
}

.news-item { margin: 0 0 0.55em 0; }

/* sponsor logos */
.sponsor-grid {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	justify-content: center;
	gap: 20px 36px;
	margin: 6px 0 18px 0;
	padding: 22px 18px 18px 18px;
	background: var(--bg-soft);
	border: 1px solid var(--border);
	border-radius: 12px;
}
.sponsor {
	display: flex;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	gap: 8px;
	width: 160px;
	min-height: 86px;
	text-align: center;
}
.sponsor img {
	height: 46px;
	width: auto;
	max-width: 150px;
	margin: 0;
	object-fit: contain;
	border-radius: 0;
}
.sponsor .s-name {
	font-size: 13px;
	color: var(--muted);
	line-height: 1.35;
}
.sponsor .s-textlogo {
	font-size: 22px;
	font-weight: 700;
	letter-spacing: 1px;
	display: flex;
	align-items: center;
	height: 46px;
}
.sponsor .s-textlogo .nsfc { color: #C62828; }   /* NSFC red */

/* --------------------------------------------------------------------------
   Responsive behavior
   -------------------------------------------------------------------------- */
@media screen and (max-width: 920px) {
	.site-nav { display: none; }
	#nav-toggle { display: inline-block; }

	body.nav-open .site-nav { display: block; }
	body.nav-open .nav-inner { padding: 4px 8px 12px 8px; }
	body.nav-open .nav-list { flex-direction: column; }
	body.nav-open .nav-item a {
		display: block;
		border-bottom: none;
		border-left: 3px solid transparent;
		padding: 9px 12px;
	}
	body.nav-open .nav-item.current a {
		border-left-color: var(--accent);
	}

	.brand-title a { font-size: 21px; }
	.brand-sub { font-size: 11px; }
	.brand-seal img { height: 44px; }
	.brand-inner { padding: 8px 16px; gap: 12px; }
	.brand-title { padding-left: 12px; }
	.brand-links { display: none; }

	.page { padding: 20px 18px 32px 18px; }

	.proj { flex-direction: column; gap: 8px; }
	.proj img { width: 100%; }

	.pi-row { flex-direction: column; align-items: center; text-align: center; }
	.pi-row img.pi-photo { width: 170px; }
	.pi-row h4 { justify-content: center; }

	h1 { font-size: 28px; }
	h2 { font-size: 22px; }
}

@media print {
	.site-header { display: none; }
}

/* small helper: keep original footer taste */
.small { font-size: 14px; color: var(--muted); }