/* ============================================================
   TIANHAO LI – PERSONAL WEBSITE  (Light Theme)
   ============================================================ */

/* --- TOKENS ------------------------------------------------- */
:root {
  --bg:           #faf9f7;
  --bg-alt:       #f3f1ed;
  --surface:      #ffffff;
  --border:       #e4e0d8;
  --border-light: #ede9e3;
  --text:         #1a1916;
  --text-muted:   #6b6760;
  --text-light:   #9c9893;
  --accent:       #2d5a8e;       /* academic blue */
  --accent-warm:  #8b5e3c;       /* warm brown for highlights */
  --accent-light: #e8f0f9;
  --link:         #2d5a8e;
  --font-serif:   'Lora', Georgia, serif;
  --font-sans:    'Inter', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', 'Courier New', monospace;
  --max-w:        1080px;
  --radius:       8px;
  --shadow-sm:    0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md:    0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --transition:   0.18s ease;
}

/* --- RESET -------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--link); text-decoration: none; transition: opacity var(--transition); }
a:hover { opacity: 0.7; }
img { display: block; max-width: 100%; }

/* --- HEADER ------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 249, 247, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}
.site-name {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  letter-spacing: 0.01em;
  white-space: nowrap;
}
.site-role {
  font-size: 0.68rem;
  color: var(--text-muted);
  letter-spacing: 0.03em;
  margin-top: 1px;
  white-space: nowrap;
}
.header-nav {
  display: flex;
  align-items: center;
  gap: 1.8rem;
  flex-shrink: 0;
}
.header-nav > a {
  color: var(--text-muted);
  font-size: 0.8rem;
  letter-spacing: 0.03em;
  font-weight: 400;
  transition: color var(--transition);
}
.header-nav > a:hover { color: var(--accent); opacity: 1; }

/* --- HEADER SOCIALS ---------------------------------------- */
.header-socials {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-left: 0.5rem;
  padding-left: 1.2rem;
  border-left: 1px solid var(--border);
}
.header-socials a {
  color: var(--text-light);
  display: flex;
  align-items: center;
  transition: color var(--transition);
}
.header-socials a:hover { color: var(--accent); opacity: 1; }

/* --- HERO --------------------------------------------------- */
.hero {
  border-bottom: 1px solid var(--border);
  padding: 5rem 2rem 4.5rem;
  background: var(--surface);
}
.hero-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 4rem;
}

/* Avatar */
.hero-avatar-col { flex-shrink: 0; }
.avatar-wrap {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  overflow: hidden;
  border: 4px solid var(--border);
  box-shadow: var(--shadow-md);
}
.avatar-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
}

/* Hero text */
.hero-text { flex: 1; }
.hero-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.75rem;
  background: var(--accent-light);
  padding: 0.2rem 0.65rem;
  border-radius: 4px;
}
.hero-headline {
  font-family: var(--font-serif);
  font-size: clamp(2.2rem, 4.5vw, 3.4rem);
  font-weight: 500;
  line-height: 1.15;
  color: var(--text);
  margin-bottom: 0.3rem;
}
.hero-tagline {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 400;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 1.1rem;
}
.hero-tagline em {
  font-style: normal;
  color: var(--accent-warm);
}
.hero-desc {
  font-size: 0.97rem;
  color: var(--text-muted);
  max-width: 480px;
  margin-bottom: 2rem;
  line-height: 1.75;
  font-weight: 300;
}
.hero-links { display: flex; gap: 0.85rem; flex-wrap: wrap; margin-bottom: 1.2rem; }

.btn-primary {
  background: var(--accent);
  color: #fff;
  padding: 0.6rem 1.4rem;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  box-shadow: var(--shadow-sm);
  transition: background var(--transition), box-shadow var(--transition);
}
.btn-primary:hover { background: #234d7a; opacity: 1; box-shadow: var(--shadow-md); }

.btn-ghost {
  color: var(--text-muted);
  border: 1px solid var(--border);
  background: var(--surface);
  padding: 0.6rem 1.3rem;
  border-radius: var(--radius);
  font-size: 0.85rem;
  letter-spacing: 0.02em;
  transition: border-color var(--transition), color var(--transition);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); opacity: 1; }

/* Social pills */
.hero-socials { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.social-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  color: var(--text-muted) !important;
  font-size: 0.75rem;
  padding: 0.3rem 0.8rem;
  border-radius: 20px;
  letter-spacing: 0.02em;
  font-weight: 400;
  transition: border-color var(--transition), color var(--transition), background var(--transition);
}
.social-pill:hover { border-color: var(--accent); color: var(--accent) !important; background: var(--accent-light); opacity: 1; }

/* --- SECTIONS ---------------------------------------------- */
.section { padding: 5rem 2rem; }
.section-alt { background: var(--bg-alt); }
.section-inner { max-width: var(--max-w); margin: 0 auto; }

.section-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
  font-weight: 500;
}
.section-title {
  font-family: var(--font-serif);
  font-size: clamp(1.7rem, 2.8vw, 2.3rem);
  font-weight: 500;
  color: var(--text);
  margin-bottom: 2.5rem;
}
.subsection-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 1.1rem;
}

/* --- ABOUT -------------------------------------------------- */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}
.about-text p {
  color: var(--text-muted);
  margin-bottom: 1rem;
  font-weight: 300;
}
.about-text p:last-child { margin-bottom: 0; }
.about-text strong { color: var(--text); font-weight: 500; }

.education-list { border-left: 2px solid var(--border); padding-left: 1.5rem; }
.edu-item { margin-bottom: 1.5rem; }
.edu-item:last-child { margin-bottom: 0; }
.edu-degree { font-weight: 500; font-size: 0.9rem; color: var(--text); }
.edu-school { font-size: 0.85rem; color: var(--accent); margin-top: 0.1rem; }
.edu-year {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-light);
  margin-top: 0.15rem;
}

/* --- RESEARCH ---------------------------------------------- */
.research-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}
.research-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.6rem;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition), border-color var(--transition);
}
.research-card:hover { box-shadow: var(--shadow-md); border-color: #c8d8ea; }
.research-tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
  font-weight: 500;
}
.research-card-title {
  font-size: 0.97rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 0.7rem;
  line-height: 1.4;
}
.research-card p { font-size: 0.875rem; color: var(--text-muted); line-height: 1.7; font-weight: 300; }

/* --- PUBLICATIONS ------------------------------------------ */
.pub-list { list-style: none; counter-reset: pub-counter; }
.pub-item {
  counter-increment: pub-counter;
  border-bottom: 1px solid var(--border-light);
  padding: 1.5rem 0;
  position: relative;
  padding-left: 2.2rem;
}
.pub-item:first-child { border-top: 1px solid var(--border-light); }
.pub-item::before {
  content: counter(pub-counter);
  position: absolute;
  left: 0;
  top: 1.65rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-light);
  line-height: 1;
}
.pub-meta {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  margin-bottom: 0.35rem;
}
.pub-journal {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--accent);
}
.pub-year {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-light);
}
.pub-under-review {
  color: #2e7d52;
  background: #edf7f1;
  padding: 0.1rem 0.45rem;
  border-radius: 3px;
  border: 1px solid #c3e6d0;
}
.pub-title {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 0.25rem;
  line-height: 1.5;
}
.pub-title a { color: var(--text); }
.pub-title a:hover { color: var(--accent); opacity: 1; }
.pub-authors { font-size: 0.82rem; color: var(--text-muted); font-weight: 300; }
.pub-authors strong { color: var(--text); font-weight: 500; }

.pres-list { border-left: 2px solid var(--border); padding-left: 1.5rem; }
.pres-item { margin-bottom: 1.4rem; }
.pres-item:last-child { margin-bottom: 0; }
.pres-venue { font-size: 0.78rem; color: var(--text-light); margin-bottom: 0.1rem; }
.pres-title { font-size: 0.9rem; font-weight: 500; color: var(--text); }
.pres-date {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-light);
  margin-top: 0.15rem;
}

/* --- OPEN SOURCE ------------------------------------------- */
.oss-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}
.oss-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
  transition: box-shadow var(--transition), border-color var(--transition);
}
.oss-card:hover { box-shadow: var(--shadow-md); border-color: #c8d8ea; }
.oss-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.oss-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}
.oss-icon-hf { background: #ffe8cc; color: #d97706; }
.oss-icon-gpt { background: #d1fae5; color: #059669; }
.oss-icon-gh { background: #f3f4f6; color: #374151; }
.oss-link {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  letter-spacing: 0.04em;
  font-weight: 500;
}
.oss-link:hover { opacity: 0.7; }
.oss-title {
  font-size: 0.97rem;
  font-weight: 600;
  color: var(--text);
  line-height: 1.3;
}
.oss-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.65;
  font-weight: 300;
  flex: 1;
}
.oss-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.2rem;
}
.oss-tags span {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.68rem;
  padding: 0.18rem 0.55rem;
  border-radius: 3px;
  font-family: var(--font-mono);
}

/* --- TEACHING ---------------------------------------------- */
.teaching-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
  margin-bottom: 3rem;
}
.teaching-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}
.teaching-meta {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--accent);
  letter-spacing: 0.1em;
  font-weight: 500;
  margin-bottom: 0.3rem;
}
.teaching-role { font-size: 0.78rem; color: var(--text-muted); margin-bottom: 0.1rem; font-weight: 300; }
.teaching-course { font-size: 0.9rem; font-weight: 500; color: var(--text); margin-bottom: 0.65rem; }
.teaching-item p { font-size: 0.85rem; color: var(--text-muted); line-height: 1.65; font-weight: 300; }

/* Skills */
.skills-block { margin-top: 1rem; }
.skills-grid { display: flex; gap: 3rem; flex-wrap: wrap; }
.skill-group-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-light);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
  font-weight: 500;
}
.skill-tags { display: flex; flex-wrap: wrap; gap: 0.45rem; }
.skill-tags span {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.75rem;
  padding: 0.22rem 0.65rem;
  border-radius: 4px;
  font-family: var(--font-mono);
}

/* --- CONTACT ----------------------------------------------- */
.contact-inner { text-align: center; max-width: 580px; margin: 0 auto; }
.contact-inner .section-label { text-align: center; }
.contact-inner .section-title { margin-bottom: 0.8rem; }
.contact-desc { color: var(--text-muted); margin-bottom: 2.2rem; font-weight: 300; font-size: 0.97rem; }
.contact-links { display: flex; gap: 0.9rem; justify-content: center; flex-wrap: wrap; }
.contact-card {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.75rem 1.2rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  box-shadow: var(--shadow-sm);
  transition: border-color var(--transition), color var(--transition), box-shadow var(--transition);
}
.contact-card:hover { border-color: var(--accent); color: var(--accent); opacity: 1; box-shadow: var(--shadow-md); }
.contact-icon { font-size: 0.95rem; }

/* --- VISITOR MAP ------------------------------------------- */
.visitor-map-section {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 2.5rem 2rem;
}
.visitor-map-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}
.visitor-map-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-light);
  font-weight: 500;
}
.visitor-map-widget {
  line-height: 0;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

/* --- FOOTER ------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.6rem 2rem;
  background: var(--surface);
}
.footer-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  text-align: center;
  font-size: 0.72rem;
  color: var(--text-light);
  font-family: var(--font-mono);
}

/* --- HERO LABEL LINK (Amazon Fellow pill) ------------------ */
.hero-label-link {
  display: inline-flex !important;
  align-items: center;
  gap: 0.5rem;
  color: var(--accent) !important;
  border: 1px solid #cfe0f4;
  transition: background var(--transition), border-color var(--transition);
}
.hero-label-link:hover { background: #dbeafe; border-color: var(--accent); opacity: 1; }
.hero-label-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #f59e0b;
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.18);
  flex-shrink: 0;
}

/* --- IMPACT STATS STRIP ------------------------------------ */
.stats-strip {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 2.2rem 2rem;
}
.stats-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}
.stat { text-align: center; padding: 0 0.5rem; }
.stat-num {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 500;
  color: var(--accent);
  line-height: 1.1;
  letter-spacing: -0.01em;
}
.stat-suffix { font-size: 0.7em; color: var(--accent-warm); margin-left: 1px; }
.stat-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-top: 0.35rem;
}

/* --- NEWS ---------------------------------------------------- */
.news-section { padding-top: 4rem; padding-bottom: 4rem; }
.news-list { list-style: none; border-left: 2px solid var(--border); padding-left: 1.5rem; }
.news-item {
  display: flex;
  gap: 1.2rem;
  padding: 0.75rem 0;
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 300;
  line-height: 1.6;
}
.news-item + .news-item { border-top: 1px solid var(--border-light); }
.news-date {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--accent);
  letter-spacing: 0.04em;
  flex-shrink: 0;
  width: 70px;
  padding-top: 0.18rem;
  font-weight: 500;
}
.news-text strong { color: var(--text); font-weight: 500; }
.news-text em { color: var(--text); font-style: italic; }

/* --- ABOUT: looking-for + edu-badge ------------------------ */
.looking-for {
  margin-top: 1.5rem;
  padding: 1rem 1.1rem;
  background: var(--accent-light);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
}
.looking-for-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.4rem;
  font-weight: 500;
}
.looking-for p {
  font-size: 0.88rem;
  color: var(--text);
  margin: 0;
  font-weight: 300;
  line-height: 1.65;
}
.looking-for strong { color: var(--text); font-weight: 500; }

.edu-badge {
  display: inline-block;
  margin-left: 0.45rem;
  font-family: var(--font-mono);
  font-size: 0.6rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  color: #b45309;
  background: #fef3c7;
  border: 1px solid #fcd34d;
  padding: 0.08rem 0.45rem;
  border-radius: 3px;
  vertical-align: middle;
  text-transform: uppercase;
}

/* --- PUBLICATIONS: in-prep + orcid ------------------------- */
.pub-in-prep {
  color: var(--accent-warm);
  background: #fbf3ea;
  padding: 0.1rem 0.45rem;
  border-radius: 3px;
  border: 1px solid #e7d4be;
}
.pub-orcid {
  margin-top: 1.8rem;
  font-size: 0.8rem;
  color: var(--text-light);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}
.pub-orcid a { color: var(--accent); }

/* --- SERVICE ------------------------------------------------ */
.service-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}
.service-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 1.4rem 1.4rem;
  box-shadow: var(--shadow-sm);
}
.service-role {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 0.55rem;
}
.service-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.65;
  font-weight: 300;
}
.service-desc em { color: var(--text); font-style: italic; font-weight: 400; }

/* --- PROJECT HIGHLIGHTS / SINGLE FIGURE -------------------- */
.highlights-intro {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-top: -1.6rem;
  margin-bottom: 2.5rem;
  max-width: 640px;
  font-weight: 300;
}
.project-story { margin-bottom: 3.5rem; }
.project-story:last-child { margin-bottom: 0; }
.project-story-header { margin-bottom: 1.2rem; }
.project-story-tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 0.5rem;
  font-weight: 500;
}
.project-story-tag em { color: var(--accent-warm); font-style: italic; font-weight: 400; }
.project-story-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 500;
  color: var(--text);
  line-height: 1.35;
  margin-bottom: 0.55rem;
}
.project-story-desc {
  color: var(--text-muted);
  font-size: 0.92rem;
  line-height: 1.7;
  font-weight: 300;
  max-width: 760px;
}
.project-story-desc strong { color: var(--text); font-weight: 500; }

.highlight-figure {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  max-width: 820px;
  transition: box-shadow var(--transition), border-color var(--transition);
}
.highlight-figure:hover { box-shadow: var(--shadow-md); border-color: #c8d8ea; }
.highlight-figure img {
  width: 100%;
  height: auto;
  display: block;
  background: #fff;
}
.highlight-figure figcaption {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 300;
  line-height: 1.6;
  padding: 0.85rem 1.1rem 1rem;
  border-top: 1px solid var(--border-light);
  background: var(--surface);
}

/* --- RESPONSIVE -------------------------------------------- */
@media (max-width: 860px) {
  .hero-inner { flex-direction: column; gap: 2rem; align-items: flex-start; }
  .avatar-wrap { width: 160px; height: 160px; }
  .about-grid { grid-template-columns: 1fr; gap: 2.5rem; }
  .research-grid { grid-template-columns: 1fr; }
  .teaching-grid { grid-template-columns: 1fr; }
  .oss-grid { grid-template-columns: 1fr; }
  .service-grid { grid-template-columns: 1fr; }
  .stats-inner { grid-template-columns: repeat(2, 1fr); gap: 1.5rem; }
  .header-nav > a { display: none; }
}

@media (max-width: 560px) {
  .header-inner { padding: 0 1.2rem; }
  .hero { padding: 3rem 1.2rem 2.5rem; }
  .section { padding: 3.5rem 1.2rem; }
  .hero-headline { font-size: 2rem; }
  .stats-inner { grid-template-columns: 1fr 1fr; }
}