/* ===================== DARK THEME (DEFAULT) ===================== */
:root,
[data-theme="dark"] {
  --bg-page:        #060f1a;
  --bg-section:     #060f1a;
  --bg-section-alt: #0d1e30;
  --bg-card:        rgba(255,255,255,0.05);
  --bg-stat:        rgba(255,255,255,0.06);
  --bg-navbar:      rgba(6,15,26,0.97);
  --bg-hero:        linear-gradient(135deg, #0a2540 0%, #1e3a5f 50%, #0f3460 100%);
  --bg-contact-box: #0d1e30;
  --bg-tag:         rgba(37,99,235,0.2);
  --bg-join:        rgba(37,99,235,0.1);
  --bg-funding:     rgba(255,255,255,0.05);
  --bg-toggle:      rgba(255,255,255,0.1);
  --bg-patent:      rgba(255,255,255,0.03);

  --text-primary:   #f0f6ff;
  --text-secondary: #94a3b8;
  --text-heading:   #ffffff;
  --text-nav:       rgba(255,255,255,0.8);
  --text-card-desc: rgba(255,255,255,0.55);
  --text-card-title:#ffffff;
  --text-card-label:#60a5fa;
  --text-course:    rgba(255,255,255,0.8);
  --text-course-lbl:rgba(255,255,255,0.45);
  --text-hero-sub:  rgba(255,255,255,0.65);
  --text-hero-tag:  #93c5fd;
  --text-hero-dept: #60a5fa;

  --accent:         #2563eb;
  --accent-light:   #3b82f6;
  --accent-text:    #60a5fa;

  --border:         rgba(255,255,255,0.1);
  --border-strong:  rgba(255,255,255,0.2);
  --border-timeline:rgba(255,255,255,0.15);

  --toggle-border:  rgba(255,255,255,0.25);
  --toggle-color:   white;

  --footer-bg:      #020810;
  --footer-text:    rgba(255,255,255,0.35);

  --granted-bg:     rgba(22,101,52,0.2);
  --granted-color:  #4ade80;
  --published-bg:   rgba(194,65,12,0.2);
  --published-color:#fb923c;
  --tag-bg:         rgba(37,99,235,0.15);
  --tag-color:      #93c5fd;

  --shadow-card:    0 12px 40px rgba(0,0,0,0.4);
  --shadow-stat:    0 2px 10px rgba(0,0,0,0.2);
}

/* ===================== LIGHT THEME ===================== */
/* [data-theme="light"] {
  --bg-page:        #ffffff;
  --bg-section:     #ffffff;
  --bg-section-alt: #f0f5fb;
  --bg-card:        #ffffff;
  --bg-stat:        #ffffff;
  --bg-navbar:      rgba(255,255,255,0.97);
  --bg-hero:        linear-gradient(135deg, #e8f0fe 0%, #dbeafe 50%, #eff6ff 100%);
  --bg-contact-box: #1e3a5f;
  --bg-tag:         rgba(37,99,235,0.08);
  --bg-join:        rgba(37,99,235,0.08);
  --bg-funding:     #f0f5fb;
  --bg-toggle:      rgba(0,0,0,0.07);
  --bg-patent:      #ffffff;

  --text-primary:   #1e293b;
  --text-secondary: #475569;
  --text-heading:   #0a2540;
  --text-nav:       #334155;
  --text-card-desc: #475569;
  --text-card-title:#0a2540;
  --text-card-label:#1d4ed8;
  --text-course:    #1e293b;
  --text-course-lbl:#475569;
  --text-hero-sub:  #334155;
  --text-hero-tag:  #1d4ed8;
  --text-hero-dept: #2563eb;

  --accent:         #2563eb;
  --accent-light:   #3b82f6;
  --accent-text:    #2563eb;

  --border:         #e2e8f0;
  --border-strong:  #cbd5e1;
  --border-timeline:#cbd5e1;

  --toggle-border:  rgba(0,0,0,0.15);
  --toggle-color:   #0a2540;

  --footer-bg:      #0a2540;
  --footer-text:    rgba(255,255,255,0.45);

  --granted-bg:     #f0fdf4;
  --granted-color:  #166534;
  --published-bg:   #fff7ed;
  --published-color:#c2410c;
  --tag-bg:         #eff6ff;
  --tag-color:      #1d4ed8;

  --shadow-card:    0 4px 20px rgba(0,0,0,0.08);
  --shadow-stat:    0 2px 10px rgba(0,0,0,0.06);
} */

/* ===================== RESET & BASE ===================== */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Source Serif 4', Georgia, serif;
  color: var(--text-primary);
  background: var(--bg-page);
  line-height: 1.7;
  transition: background 0.3s ease, color 0.3s ease;
}

/* ===================== NAVBAR ===================== */
.navbar {
  position: sticky; top: 0; z-index: 1000;
  background: var(--bg-navbar);
  backdrop-filter: blur(10px);
  padding: 0 2rem;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
  box-shadow: 0 2px 20px rgba(0,0,0,0.15);
  transition: background 0.3s ease, box-shadow 0.3s ease;
}
.navbar-brand {
  font-family: 'Playfair Display', serif;
  font-size: 1.1rem; font-weight: 600; letter-spacing: 0.02em;
  color: var(--text-heading);
  text-decoration: none;
  transition: color 0.3s;
}
.navbar-nav { display: flex; gap: 0.2rem; list-style: none; align-items: center; }
.navbar-nav a {
  color: var(--text-nav);
  text-decoration: none;
  font-family: 'DM Sans', sans-serif;
  font-size: 0.8rem; font-weight: 500;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 0.4rem 0.75rem; border-radius: 4px;
  transition: color 0.2s, background 0.2s;
}
[data-theme="dark"] .navbar-nav a:hover  { color: #ffffff; background: rgba(255,255,255,0.1); }
[data-theme="light"] .navbar-nav a:hover { color: #0a2540; background: rgba(0,0,0,0.06); }

/* ===================== THEME TOGGLE ===================== */
.theme-toggle {
  background: var(--bg-toggle);
  border: 1px solid var(--toggle-border);
  color: var(--toggle-color);
  width: 38px; height: 38px; border-radius: 50%;
  cursor: pointer; font-size: 1rem;
  display: flex; align-items: center; justify-content: center;
  transition: all 0.25s;
  margin-left: 0.75rem; flex-shrink: 0;
}
.theme-toggle:hover { transform: rotate(20deg) scale(1.1); }

/* ===================== HERO ===================== */
.hero {
  background: var(--bg-hero);
  min-height: 100vh;
  display: grid; grid-template-columns: 1fr 1fr;
  align-items: center; padding: 6rem 8%; gap: 4rem;
  position: relative; overflow: hidden;
  transition: background 0.3s ease;
}
.hero::before {
  content: ''; position: absolute;
  top: -200px; right: -200px; width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(37,99,235,0.15) 0%, transparent 70%);
  border-radius: 50%;
}
.hero-content { position: relative; z-index: 1; }
.hero-dept {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.75rem; font-weight: 600; letter-spacing: 0.2em; text-transform: uppercase;
  color: var(--text-hero-dept); margin-bottom: 1.5rem;
}
.hero h1 {
  font-family: 'Playfair Display', serif;
  /*font-size: clamp(2.5rem, 5vw, 4rem);*/
  font-size: 3.8rem !important;
  color: var(--text-heading); line-height: 1.15;
  margin-bottom: 0.75rem; font-weight: 700;
}
.hero-subtitle {
  font-family: 'DM Sans', sans-serif;
  color: var(--text-hero-sub); font-size: 1.05rem;
  margin-bottom: 2rem; letter-spacing: 0.02em;
}
.hero-tags { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 2.5rem; }
.hero-tag {
  background: var(--bg-tag);
  border: 1px solid var(--border-strong);
  color: var(--text-hero-tag);
  padding: 0.3rem 0.9rem; border-radius: 20px;
  font-family: 'DM Sans', sans-serif;
  font-size: 0.78rem; font-weight: 500; letter-spacing: 0.05em;
}
.hero-btns { display: flex; gap: 1rem; flex-wrap: wrap; }
.btn-primary {
  background: var(--accent); color: white;
  padding: 0.75rem 1.75rem; border-radius: 6px;
  text-decoration: none; font-family: 'DM Sans', sans-serif;
  font-weight: 600; font-size: 0.9rem;
  transition: all 0.2s; letter-spacing: 0.03em;
}
.btn-primary:hover { background: var(--accent-light); transform: translateY(-1px); box-shadow: 0 4px 15px rgba(37,99,235,0.4); }
.btn-outline {
  border: 1.5px solid var(--border-strong);
  color: var(--text-hero-sub);
  padding: 0.75rem 1.75rem; border-radius: 6px;
  text-decoration: none; font-family: 'DM Sans', sans-serif;
  font-weight: 500; font-size: 0.9rem; transition: all 0.2s;
}
[data-theme="dark"] .btn-outline:hover  { border-color: white; color: white; background: rgba(255,255,255,0.08); }
[data-theme="light"] .btn-outline:hover { border-color: #0a2540; color: #0a2540; background: rgba(0,0,0,0.05); }
.hero-image-wrap {
  display: flex; justify-content: center; align-items: center; position: relative;
}
.hero-image-wrap::before {
  content: ''; position: absolute;
  width: 340px; height: 340px;
  background: radial-gradient(circle, rgba(37,99,235,0.2), transparent 70%);
  border-radius: 50%;
}
.hero-img {
  width: 300px; height: 300px; border-radius: 50%; object-fit: cover;
  border: 4px solid var(--border-strong);
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
  position: relative; z-index: 1;
}

/* ===================== SECTIONS ===================== */
.section { padding: 5rem 8%; background: var(--bg-section); transition: background 0.3s; }
.section-alt { background: var(--bg-section-alt) !important; }
.section-label {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.7rem; font-weight: 700; letter-spacing: 0.25em; text-transform: uppercase;
  color: var(--accent-text); margin-bottom: 0.75rem;
}
.section-title {
  font-family: 'Playfair Display', serif;
  font-size: clamp(1.8rem, 3vw, 2.5rem);
  color: var(--text-heading); margin-bottom: 1.5rem;
  font-weight: 700; line-height: 1.25;
}
.section-sub {
  color: var(--text-secondary); font-family: 'DM Sans', sans-serif;
  max-width: 600px; margin-bottom: 3rem; font-size: 1rem;
}

/* ===================== ABOUT ===================== */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 5rem; align-items: start; }
.about-text p { color: var(--text-secondary); margin-bottom: 1.2rem; font-size: 1.02rem; line-height: 1.8; }
.about-text strong { color: var(--text-primary); }
.stats-row { display: grid; grid-template-columns: repeat(4,1fr); gap: 1.5rem; margin-top: 2.5rem; }
.stat-box {
  text-align: center; padding: 1.5rem 1rem;
  background: var(--bg-stat); border-radius: 10px;
  border: 1px solid var(--border); box-shadow: var(--shadow-stat);
  transition: background 0.3s, border-color 0.3s;
}
.stat-num {
  font-family: 'Playfair Display', serif; font-size: 2.2rem; font-weight: 700;
  color: var(--accent-text); line-height: 1; margin-bottom: 0.4rem;
}
.stat-label { font-family: 'DM Sans', sans-serif; font-size: 0.78rem; color: var(--text-secondary); text-transform: none; letter-spacing: 0.08em; }
.timeline { list-style: none; }
.timeline li {
  padding: 1rem 0 1rem 1.5rem;
  border-left: 2px solid var(--border-timeline);
  position: relative; margin-left: 0.5rem;
}
.timeline li::before {
  content: ''; width: 10px; height: 10px;
  background: var(--accent); border-radius: 50%;
  position: absolute; left: -6px; top: 1.3rem;
}
.timeline-role { font-family: 'DM Sans', sans-serif; font-weight: 700; font-size: 0.95rem; color: var(--text-primary); }
.timeline-org  { font-family: 'DM Sans', sans-serif; font-size: 0.85rem; color: var(--text-secondary); }
.timeline-period { font-family: 'DM Sans', sans-serif; font-size: 0.8rem; color: var(--accent-text); font-weight: 500; }
.edu-item { padding: 0.75rem 0; border-bottom: 1px solid var(--border); }
.edu-item:last-child { border-bottom: none; }
.edu-degree { font-family: 'DM Sans', sans-serif; font-weight: 700; color: var(--text-primary); }
.edu-inst    { font-family: 'DM Sans', sans-serif; font-size: 0.85rem; color: var(--text-secondary); }

/* ===================== RESEARCH ===================== */
.research-tags-nav { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 2.5rem; }
.res-tag-btn {
  background: var(--bg-card); border: 1px solid var(--border);
  color: var(--text-secondary);
  padding: 0.35rem 1rem; border-radius: 20px;
  font-family: 'DM Sans', sans-serif; font-size: 0.78rem; font-weight: 600;
  letter-spacing: 0.08em; cursor: pointer; transition: all 0.2s;
}
.res-tag-btn.active, .res-tag-btn:hover { background: var(--accent); border-color: var(--accent); color: white; }
.research-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 1.5rem; }
.research-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 12px; overflow: hidden; transition: all 0.3s;
}
.research-card:hover { transform: translateY(-4px); border-color: var(--accent); box-shadow: var(--shadow-card); }
.research-card img { width: 100%; height: 180px; object-fit: cover; }
.card-body { padding: 1.4rem; }
.card-label { font-family: 'DM Sans', sans-serif; font-size: 0.68rem; font-weight: 700; letter-spacing: 0.2em; color: var(--text-card-label); margin-bottom: 0.5rem; }
.card-title { font-family: 'Playfair Display', serif; font-size: 1.05rem; color: var(--text-card-title); margin-bottom: 0.75rem; line-height: 1.35; font-weight: 600; }
.card-desc  { font-family: 'DM Sans', sans-serif; font-size: 0.82rem; color: var(--text-card-desc); line-height: 1.65; }

/* ===================== PUBLICATIONS ===================== */
.pub-filters { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 2rem; }
.pub-filter {
  border: 1.5px solid var(--border); background: transparent;
  color: var(--text-secondary);
  padding: 0.35rem 1.1rem; border-radius: 20px;
  font-family: 'DM Sans', sans-serif; font-size: 0.8rem; font-weight: 600;
  cursor: pointer; transition: all 0.2s;
}
.pub-filter.active, .pub-filter:hover { background: var(--accent); border-color: var(--accent); color: white; }
.pub-list { display: flex; flex-direction: column; }
.pub-item {
  display: grid; grid-template-columns: 60px 1fr; gap: 1.5rem;
  padding: 1.5rem 0; border-bottom: 1px solid var(--border);
  align-items: start; transition: all 0.2s;
}
.pub-item:hover { background: var(--bg-section-alt); border-radius: 8px; padding-left: 1rem; }
.pub-num   { font-family: 'Playfair Display', serif; font-size: 1.4rem; color: var(--accent-text); font-weight: 700; padding-top: 0.1rem; }
.pub-title  { font-size: 1rem; color: var(--text-primary); margin-bottom: 0.3rem; line-height: 1.45; font-weight: 600; }
.pub-authors{ font-family: 'DM Sans', sans-serif; font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 0.3rem; }
.pub-journal{ font-family: 'DM Sans', sans-serif; font-size: 0.82rem; color: var(--text-secondary); font-style: italic; }
.pub-tag {
  display: inline-block; background: var(--tag-bg); color: var(--tag-color);
  font-family: 'DM Sans', sans-serif; font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.1em; padding: 0.15rem 0.6rem; border-radius: 4px; margin-top: 0.4rem;
}

/* ===================== PATENTS ===================== */
.patents-stats { display: flex; gap: 2rem; margin-bottom: 3rem; }
.p-stat { text-align: center; }
.p-stat-num   { font-family: 'Playfair Display', serif; font-size: 2.5rem; font-weight: 700; color: var(--accent-text); line-height: 1; }
.p-stat-label { font-family: 'DM Sans', sans-serif; font-size: 0.78rem; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.1em; }
.patent-item {
  padding: 1.5rem; border: 1px solid var(--border); border-radius: 10px;
  margin-bottom: 1rem; background: var(--bg-patent); transition: all 0.2s;
}
.patent-item:hover { box-shadow: var(--shadow-card); border-color: var(--accent); }
.patent-header { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.5rem; }
.patent-status {
  font-family: 'DM Sans', sans-serif; font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.1em; padding: 0.2rem 0.6rem; border-radius: 4px;
}
.patent-status.granted   { background: var(--granted-bg);   color: var(--granted-color); }
.patent-status.published { background: var(--published-bg); color: var(--published-color); }
.patent-year      { font-family: 'DM Sans', sans-serif; font-size: 0.82rem; color: var(--text-secondary); font-weight: 600; }
.patent-title     { font-size: 0.98rem; color: var(--text-primary); font-weight: 600; margin-bottom: 0.3rem; line-height: 1.45; }
.patent-appno     { font-family: 'DM Sans', sans-serif; font-size: 0.8rem; color: var(--text-secondary); font-style: italic; margin-bottom: 0.3rem; }
.patent-inventors { font-family: 'DM Sans', sans-serif; font-size: 0.8rem; color: var(--text-secondary); }

/* ===================== STUDENTS ===================== */
.students-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
.students-group-title {
  font-family: 'DM Sans', sans-serif; font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.2em; text-transform: uppercase;
  color: var(--accent-text); margin-bottom: 1.5rem;
}
.student-card {
  padding: 1.25rem 1.5rem;
  border-left: 3px solid var(--accent);
  background: var(--bg-card); border-radius: 0 8px 8px 0;
  margin-bottom: 1rem; box-shadow: var(--shadow-stat);
  transition: background 0.3s;
}
.student-name  { font-family: 'DM Sans', sans-serif; font-weight: 700; font-size: 0.95rem; color: var(--text-primary); margin-bottom: 0.25rem; }
.student-topic { font-family: 'DM Sans', sans-serif; font-size: 0.82rem; color: var(--text-secondary); line-height: 1.5; }

/* ===================== TEACHING ===================== */
.teaching-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
.course-group-title {
  font-family: 'DM Sans', sans-serif; font-size: 0.7rem; font-weight: 700;
  letter-spacing: 0.2em; text-transform: uppercase;
  color: var(--text-course-lbl); margin-bottom: 1.5rem;
}
.course-item {
  display: flex; gap: 1rem; align-items: start;
  padding: 1rem 0; border-bottom: 1px solid var(--border);
}
.course-code { font-family: 'DM Sans', sans-serif; font-size: 0.75rem; font-weight: 700; color: var(--accent-text); min-width: 70px; padding-top: 0.1rem; }
.course-name { font-family: 'DM Sans', sans-serif; font-size: 0.9rem; color: var(--text-course); }
.join-box {
  background: var(--bg-join); border: 1px solid var(--border);
  border-radius: 10px; padding: 2rem; margin-top: 3rem;
}
.join-box h4 { font-family: 'Playfair Display', serif; color: var(--text-heading); font-size: 1.3rem; margin-bottom: 1rem; }
.join-box p  { font-family: 'DM Sans', sans-serif; color: var(--text-secondary); font-size: 0.9rem; line-height: 1.7; margin-bottom: 0.5rem; }
.join-box strong { color: var(--text-primary); }

/* ===================== CONTACT ===================== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 4rem; align-items: start; }
.contact-items { display: flex; flex-direction: column; gap: 1.5rem; }
.contact-item  { display: flex; gap: 1.25rem; align-items: start; }
.contact-icon  { font-size: 1.5rem; flex-shrink: 0; }
.contact-label { font-family: 'DM Sans', sans-serif; font-size: 0.7rem; font-weight: 700; letter-spacing: 0.2em; text-transform: uppercase; color: var(--accent-text); margin-bottom: 0.25rem; }
.contact-val   { font-family: 'DM Sans', sans-serif; font-size: 0.95rem; color: var(--text-primary); }
.contact-val a { color: var(--accent-text); text-decoration: none; }
.contact-val a:hover { text-decoration: underline; }
.contact-box {
  background: var(--bg-contact-box); border-radius: 12px; padding: 2.5rem;
}
.contact-box h4 { font-family: 'Playfair Display', serif; font-size: 1.4rem; margin-bottom: 1rem; color: #ffffff; }
.contact-box p  { font-family: 'DM Sans', sans-serif; font-size: 0.9rem; color: rgba(255,255,255,0.65); line-height: 1.7; margin-bottom: 0.75rem; }
.contact-box strong { color: #ffffff; }
.btn-email {
  display: inline-block; background: var(--accent); color: white;
  padding: 0.75rem 1.75rem; border-radius: 6px; text-decoration: none;
  font-family: 'DM Sans', sans-serif; font-weight: 600; font-size: 0.9rem;
  margin-top: 1rem; transition: all 0.2s;
}
.btn-email:hover { background: var(--accent-light); }
.funding-note {
  background: var(--bg-funding); border-left: 3px solid var(--accent);
  padding: 1rem 1.5rem; border-radius: 0 8px 8px 0; margin-top: 2rem;
  font-family: 'DM Sans', sans-serif; font-size: 0.85rem; color: var(--text-secondary);
  transition: background 0.3s;
}
.funding-note strong { color: var(--text-primary); }

/* ===================== FOOTER ===================== */
footer { background: var(--footer-bg); padding: 2rem 8%; text-align: center; transition: background 0.3s; }
footer p { font-family: 'DM Sans', sans-serif; font-size: 0.82rem; color: var(--footer-text); }

/* ===================== RESPONSIVE ===================== */
@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; text-align: center; padding: 4rem 5%; }
  .hero-image-wrap { display: none; }
  .hero-tags { justify-content: center; }
  .about-grid, .research-grid, .students-grid, .teaching-grid, .contact-grid { grid-template-columns: 1fr; }
  .stats-row { grid-template-columns: 1fr 1fr; }
  .navbar-nav { display: none; }
  .section { padding: 3rem 5%; }
}