/* Theme & variables */
[data-dark="false"] {
  --primary: #0795d9;
  --secondary: #7dd3fc;
  --text: #000000;
  --background: #ffffff;
  --background-alt: #fafafa;
  --light-gray: #e0e0e0;
  --gray: #808080;
  --dark-gray: #404040;
  --overlay: #00000020;
}
[data-dark="true"] {
  --primary: #0795d9;
  --secondary: #075985;
  --text: #ffffff;
  --background: #181818;
  --background-alt: #1c1c1c;
  --light-gray: #404040;
  --gray: #808080;
  --dark-gray: #b0b0b0;
  --overlay: #ffffff10;
}
:root {
  --title: "Barlow", sans-serif;
  --heading: "Barlow", sans-serif;
  --body: "Barlow", sans-serif;
  --code: "Roboto Mono", monospace;
  --large: 1.45rem;
  --xl: 1.75rem;
  --xxl: 2.1rem;
  --thin: 200;
  --regular: 400;
  --semi-bold: 500;
  --bold: 600;
  --spacing: 2;
  --compact: 1.5;
  --rounded: 3px;
  --shadow: 0 0 10px 0 var(--overlay);
  --transition: 0.2s ease;
}

/* Base */
body {
  display: flex;
  flex-direction: column;
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background: var(--background);
  color: var(--text);
  font-family: var(--body);
  font-size: 1.2rem;
  text-align: center;
  line-height: var(--compact);
}
main { display: flex; flex-direction: column; flex-grow: 1; }

/* Links */
a { color: var(--primary); transition: color var(--transition); overflow-wrap: break-word; }
a:hover { color: var(--text); }
a:not([href]) { color: var(--text); }

/* Background utility — 通用占位，section 里用 */
.background {
  position: relative;
  background: var(--background);
  color: var(--text);
  z-index: 1;
}
/* header/footer 背景图：inline style 直接写，无需 ::before */
header.background.has-bg,
footer.background.has-bg {
  color: #f5f5f5;
}
header.background.has-bg a,
footer.background.has-bg a {
  color: #f5f5f5;
}
header.background.has-bg a:hover,
footer.background.has-bg a:hover {
  color: #7dd3fc;
}
header.background.has-bg .title {
  color: #fef6e8;
  text-shadow: 0 1px 6px rgba(0,0,0,0.6), 0 2px 18px rgba(0,0,0,0.4);
}
header.background.has-bg .subtitle {
  opacity: 1;
  color: #fcd9a0;
  text-shadow: 0 1px 5px rgba(0,0,0,0.55), 0 2px 12px rgba(0,0,0,0.35);
}
header.background.has-bg nav > a {
  color: #faeaea;
  text-shadow: 0 1px 6px rgba(0,0,0,0.8), 0 0 12px rgba(0,0,0,0.5);
  font-weight: 600;
}
header.background.has-bg nav > a:hover {
  color: #ffffff;
}

/* Header */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
  padding: 20px;
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 10;
}
header a { color: var(--text); text-decoration: none; }
.home {
  display: flex;
  justify-content: flex-start;
  align-items: center;
  gap: 10px;
  flex-basis: 0;
  flex-grow: 1;
  max-width: 100%;
}
.logo { height: 40px; }
.logo > * { width: unset; height: 100%; }
.title-text {
  display: flex;
  justify-content: flex-start;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 5px;
  min-width: 0;
  font-family: var(--title);
  text-align: left;
}
.title { font-size: var(--large); }
.subtitle { opacity: 0.65; font-weight: var(--thin); }
.nav-toggle {
  display: none;
  position: relative;
  width: 30px;
  height: 30px;
  margin: 0;
  color: var(--text);
  appearance: none;
  transition: background var(--transition);
}
.nav-toggle::after {
  content: "\f0c9";
  position: absolute;
  left: 50%;
  top: 50%;
  color: var(--text);
  font-size: 15px;
  font-family: "Font Awesome 6 Free";
  font-weight: 900;
  transform: translate(-50%, -50%);
}
.nav-toggle:checked::after { content: "\f00d"; }
nav {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-family: var(--heading);
  font-size: 1.1rem;
  text-transform: uppercase;
}
nav > a { padding: 5px; }
nav > a:hover { color: var(--primary); }
@media (max-width: 700px) {
  header:not([data-big]) {
    justify-content: flex-end;
  }
  .nav-toggle { display: flex; }
  .nav-toggle:not(:checked) + nav { display: none; }
  nav { align-items: flex-end; flex-direction: column; width: 100%; }
}
header[data-big] {
  justify-content: center;
  align-items: center;
  flex-direction: column;
  padding: 100px 20px;
  top: unset;
}
header[data-big] .home { flex-direction: column; flex-grow: 0; }
header[data-big] .logo { height: 80px; flex-shrink: 0; }
header[data-big] .title-text { flex-direction: column; align-items: center; text-align: center; }
header[data-big] .title { font-size: var(--xxl); }
header[data-big] .subtitle { font-size: var(--large); }

/* Section */
section {
  padding: 40px max(40px, calc((100% - 1000px) / 2));
  transition: background var(--transition), color var(--transition);
}
section[data-size="wide"] { padding: 40px; }
section[data-size="full"] { padding: 0; }
section[data-size="full"] > * { margin: 0; border-radius: 0; }
main > section:last-of-type { flex-grow: 1; }
main > section:nth-of-type(odd) { background: var(--background); }
main > section:nth-of-type(even) { background: var(--background-alt); }

/* Typography */
h1, h2, h3, h4, h5, h6 {
  margin: 40px 0 20px 0;
  font-family: var(--heading);
  font-weight: var(--semi-bold);
  text-align: left;
  letter-spacing: 1px;
}
h1 { margin: 40px 0; font-size: 2.4rem; font-weight: var(--regular); text-transform: uppercase; text-align: center; }
h2 { font-size: 2.1rem; padding-bottom: 5px; border-bottom: solid 1px var(--light-gray); font-weight: var(--regular); }
h3 { font-size: 1.95rem; }
h4 { font-size: 1.65rem; }
h5 { font-size: 1.4rem; }
h6 { font-size: 1.25rem; }
:where(h1, h2, h3, h4, h5, h6) > .icon { margin-right: 1em; color: var(--light-gray); }
p { margin: 20px 0; text-align: justify; line-height: var(--spacing); }
ul { margin: 6px 0 12px 0; padding-left: 1.4em; list-style-position: outside; text-align: left; }
li { margin: 0.25em 0; line-height: 1.5; text-align: left; }

/* Buttons */
.button-wrapper { display: contents; }
.button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  max-width: calc(100% - 5px - 5px);
  margin: 5px;
  padding: 8px 15px;
  border: none;
  border-radius: var(--rounded);
  background: var(--primary);
  color: var(--background);
  text-align: center;
  font: inherit;
  font-family: var(--heading);
  font-weight: var(--semi-bold);
  text-decoration: none;
  vertical-align: middle;
  appearance: none;
  transition: background var(--transition), color var(--transition);
}
.button:hover { background: var(--text); color: var(--background); }
.button[data-style="bare"] { padding: 5px; background: none; color: var(--primary); }
.button[data-style="bare"]:hover { color: var(--text); }

/* Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(var(--repeat, 3), 1fr);
  justify-content: center;
  align-items: flex-start;
  gap: 40px;
  margin: 40px 0;
}
.grid > * { min-width: 0; min-height: 0; width: 100%; margin: 0; }
@media (max-width: 750px) { .grid { --repeat: 2; } }
@media (max-width: 500px) { .grid { --repeat: 1; } }

/* Cols */
.cols {
  display: grid;
  grid-template-columns: repeat(min(3, var(--cols, 3)), 1fr);
  align-items: flex-start;
  gap: 40px;
  margin: 40px 0;
  text-align: left;
}
.cols > * { min-width: 0; min-height: 0; }
@media (max-width: 750px) { .cols { grid-template-columns: repeat(min(2, var(--cols)), 1fr); } }
@media (max-width: 500px) { .cols { grid-template-columns: 1fr; } }

/* Highlight cards & carousel */
section:has(.highlights-grid) { padding-left: 100px; padding-right: 100px; }
@media (max-width: 900px) { section:has(.highlights-grid) { padding-left: 24px; padding-right: 24px; } }
@media (max-width: 600px) { section:has(.highlights-grid) { padding-left: 12px; padding-right: 12px; } }
.highlights-grid {
  display: flex;
  flex-direction: column;
  gap: 48px;
  margin: 40px 0;
}
.highlights-grid .highlight-card { width: 100%; max-width: 100%; flex: 0 0 auto; }
.highlight-card {
  display: flex;
  flex-direction: column;
  border-radius: 8px;
  box-shadow: 0 2px 16px 0 var(--overlay);
  overflow: hidden;
  background: var(--background-alt);
  transition: box-shadow var(--transition), transform var(--transition);
}
.highlight-card:hover {
  box-shadow: 0 6px 28px 0 var(--overlay);
  transform: translateY(-2px);
}
.highlights-grid .highlight-card--horizontal { flex-direction: row; align-items: stretch; }
.highlights-grid .highlight-card--horizontal .hc-carousel { flex: 0 0 55%; min-width: 0; order: 1; display: flex; flex-direction: column; }
.highlights-grid .highlight-card--horizontal .hc-carousel .hc-carousel-viewport { flex: 1; aspect-ratio: unset; min-height: 200px; }
.highlights-grid .highlight-card--horizontal .hc-carousel .hc-carousel-placeholder { flex: 1; aspect-ratio: unset; min-height: 200px; }
.highlights-grid .highlight-card--horizontal .hc-body { flex: 1; min-width: 0; justify-content: center; order: 2; }
@media (max-width: 800px) {
  .highlights-grid .highlight-card--horizontal { flex-direction: column; }
  .highlights-grid .highlight-card--horizontal .hc-carousel { flex: 0 0 auto; width: 100%; order: 1; }
  .highlights-grid .highlight-card--horizontal .hc-body { order: 2; }
  .highlights-grid .highlight-card--horizontal .hc-carousel-viewport,
  .highlights-grid .highlight-card--horizontal .hc-carousel-placeholder { aspect-ratio: 4/3; }
  .hc-body { padding: 14px 14px 16px; gap: 8px; }
  .hc-title { font-size: 1.35rem; }
  .hc-subtitle { font-size: 0.95rem; }
  .hc-desc { font-size: 1rem; }
  .hc-learn-link { font-size: 1rem; }
  .highlights-grid { gap: 32px; margin: 24px 0; }
}
.hc-carousel-viewport {
  position: relative;
  width: 100%;
  aspect-ratio: 1408/768;
  overflow: hidden;
  background: var(--light-gray);
}
.hc-carousel-track {
  display: flex;
  height: 100%;
  transition: transform 0.45s cubic-bezier(0.4, 0, 0.2, 1);
}
.hc-carousel-slide { min-width: 100%; height: 100%; }
.hc-carousel-slide img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: center;
  display: block;
  background: var(--background-alt);
}
.hc-carousel-slide a { display: block; width: 100%; height: 100%; }
.hc-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: rgba(0,0,0,0.45);
  color: #fff;
  border: none;
  width: 36px;
  height: 36px;
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  border-radius: 4px;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition);
}
.hc-btn:hover { background: rgba(0,0,0,0.7); }
.hc-prev { left: 10px; }
.hc-next { right: 10px; }
.hc-dots {
  position: absolute;
  bottom: 10px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 7px;
  z-index: 2;
}
.hc-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: rgba(255,255,255,0.5);
  border: none;
  cursor: pointer;
  padding: 0;
  transition: background var(--transition);
}
.hc-dot.active { background: #fff; }
.hc-captions { width: 100%; }
.hc-caption {
  display: none;
  margin: 0;
  padding: 3px 6px 4px;
  font-size: 0.72rem;
  line-height: 1.3;
  color: #c0392b;
  text-align: left;
  font-style: italic;
}
.hc-caption.active { display: block; }
.hc-carousel-placeholder {
  width: 100%;
  aspect-ratio: 1408/768;
  background: var(--background-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  border-bottom: 1px solid var(--light-gray);
}
.hc-placeholder-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  color: var(--light-gray);
  font-size: 1.15rem;
}
.hc-placeholder-inner .icon, .hc-placeholder-inner i { font-size: 2.5rem; }
.hc-body {
  padding: 20px 14px 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  text-align: left;
  flex-grow: 1;
}
.hc-title { margin: 0; font-size: 1.75rem; font-family: var(--heading); font-weight: var(--bold); line-height: 1.3; }
.hc-title-link { color: var(--text); text-decoration: none; transition: color var(--transition); }
.hc-title-link:hover { color: var(--primary); }
.hc-subtitle { margin: 0; font-size: 1.1rem; font-style: italic; color: var(--primary); line-height: 1.4; }
.hc-descs { min-height: 3.5em; }
.hc-desc { display: none; margin: 0; font-size: 1.15rem; line-height: 1.5; color: var(--dark-gray); text-align: left; }
.hc-desc.active { display: block; }
.hc-learn-link {
  margin-top: auto;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--primary);
  font-weight: var(--semi-bold);
  font-size: 1.12rem;
  text-decoration: none;
  transition: gap var(--transition), color var(--transition);
}
.hc-learn-link:hover { gap: 10px; color: var(--secondary); }

/* Project detail */
section:has(.project-detail) { background: var(--background); }
.project-detail h2 { font-weight: var(--bold); margin-top: 36px; }
.project-detail h2:first-of-type { margin-top: 0; }
.project-detail ul { margin: 6px 0 16px 0; padding-left: 1.4em; list-style-position: outside; text-align: left; }
.project-detail li { margin: 0.25em 0; line-height: 1.5; text-align: left; }
.project-detail p { margin: 12px 0; }

/* Portrait / team grid */
.portrait-wrapper { display: contents; }
.portrait-card-grid .portrait-wrapper { display: flex; }
.portrait {
  position: relative;
  display: inline-flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  margin: 20px;
  width: 175px;
  max-width: calc(100% - 40px);
  text-decoration: none;
  color: inherit;
}
.portrait .portrait-image {
  width: 100%;
  margin-bottom: 20px;
  aspect-ratio: 1/1;
  border-radius: 999px;
  object-fit: cover;
  box-shadow: var(--shadow);
}
.portrait-name { font-family: var(--heading); font-weight: var(--semi-bold); }
.portrait-description { width: 100%; word-break: break-word; text-align: center; font-size: 0.82em; line-height: 1.4; }
.portrait--no-link { cursor: default; }
.portrait--no-link:hover { opacity: 1; }
.portrait-card-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 28px;
  margin: 24px 0;
  align-items: stretch;
}
/* 空一行再排 RA */
.portrait-card-grid--ra {
  margin-top: 3em;
}
@media (max-width: 1000px) { .portrait-card-grid { grid-template-columns: repeat(4, 1fr); gap: 20px; } }
@media (max-width: 700px) { .portrait-card-grid { grid-template-columns: repeat(3, 1fr); gap: 14px; } }
@media (max-width: 480px) { .portrait-card-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; } }
.portrait-card-grid .portrait {
  width: 100%;
  height: 100%;
  max-width: none;
  margin: 0;
  padding: 0;
  border-radius: 14px;
  overflow: hidden;
  flex-direction: column;
  align-items: center;
  box-shadow: 0 2px 10px rgba(30,100,180,0.12);
  transition: box-shadow var(--transition), transform var(--transition);
}
.portrait-card-grid .portrait:not(.portrait--no-link):hover {
  box-shadow: 0 6px 22px rgba(30,100,180,0.24);
  transform: translateY(-3px);
}
.portrait-card-grid .portrait .icon { display: none; }
.portrait-card-grid .portrait-description { display: none; }
.portrait-card-grid .portrait-affiliation { display: none; }
/* 1:1 正方形照片区域，cover 填满无留白，偏上取景保留脸部 */
.portrait-card-grid .portrait-image-box {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  overflow: hidden;
  flex-shrink: 0;
  background: var(--light-gray);
}
.portrait-card-grid .portrait-image-box .portrait-image {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
  object-position: center 30%;
  margin: 0;
  border-radius: 0;
  box-shadow: none;
}
.portrait-card-grid .portrait-image-placeholder {
  width: 100%;
  aspect-ratio: 1 / 1;
  flex-shrink: 0;
  background: var(--light-gray);
}
.portrait-card-grid .portrait-image-box .portrait-image-placeholder {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}
.portrait-card-grid .portrait-name {
  width: 100%;
  padding: 12px 10px 2px;
  box-sizing: border-box;
  text-align: center;
  font-size: 0.92em;
  color: hsl(220,45%,20%);
  line-height: 1.3;
}
.portrait-card-grid .portrait-affiliation {
  width: 100%;
  padding: 3px 10px 14px;
  box-sizing: border-box;
  text-align: center;
  font-size: 0.72em;
  color: hsl(215,35%,42%);
  line-height: 1.3;
}
.portrait-card-grid .portrait-group-label {
  width: 100%;
  padding: 2px 10px 14px;
  box-sizing: border-box;
  text-align: center;
  font-size: 0.75em;
  font-weight: var(--semi-bold);
  color: hsl(215,40%,38%);
  line-height: 1.3;
}
.portrait-card-grid .portrait-group--lab-leader .portrait {
  background: linear-gradient(180deg, hsl(250,55%,94%) 60%, hsl(250,45%,88%) 100%);
}
.portrait-card-grid .portrait-group--phd .portrait {
  background: linear-gradient(180deg, hsl(210,60%,94%) 60%, hsl(210,50%,87%) 100%);
}
.portrait-card-grid .portrait-group--ra .portrait {
  background: linear-gradient(180deg, hsl(185,55%,93%) 60%, hsl(185,45%,87%) 100%);
}
.portrait-card-grid .portrait-group--alumni .portrait {
  background: linear-gradient(180deg, hsl(210,60%,94%) 60%, hsl(210,50%,87%) 100%);
}

/* Footer */
footer {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  gap: 20px;
  padding: 40px;
  line-height: var(--spacing);
  box-shadow: var(--shadow);
}
footer a { color: var(--text); }
footer a:hover { color: var(--primary); }
footer .icon { font-size: var(--xl); }

/* Dark toggle */
.dark-toggle {
  position: relative;
  width: 40px;
  height: 25px;
  margin: 0;
  border-radius: 999px;
  background: var(--primary);
  appearance: none;
  transition: background var(--transition);
  cursor: pointer;
}
.dark-toggle::after {
  content: "\f185";
  position: absolute;
  left: 12px;
  top: 50%;
  color: var(--text);
  font-size: 15px;
  font-family: "Font Awesome 6 Free";
  font-weight: 900;
  transform: translate(-50%, -50%);
  transition: left var(--transition);
  pointer-events: none;
}
.dark-toggle:checked::after {
  content: "\f186";
  left: calc(100% - 12px);
}