/* =========================================
   Custom Properties
   ========================================= */
:root {
  --bg:           #0a0a0a;
  --surface:      #111111;
  --border:       #1e1e1e;
  --border-hover: #3a3a3a;
  --text-1:       #f1f5f9;
  --text-2:       #a0b4c8;
  --text-3:       #64748b;
  --nav-h:        60px;
  --max-w:        1080px;
  --pad-section:  88px;
}

/* =========================================
   Light Theme Overrides
   ========================================= */
[data-theme="light"] {
  --bg:           #f1f5f9;
  --surface:      #ffffff;
  --border:       #e2e8f0;
  --border-hover: #94a3b8;
  --text-1:       #0f172a;
  --text-2:       #334155;
  --text-3:       #526a87;
}

[data-theme="light"] #nav {
  background: rgba(241, 245, 249, 0.92);
}

[data-theme="light"] .nav-links {
  background: rgba(241, 245, 249, 0.97);
}

/* Cards float with shadow — no color-patch sections */
[data-theme="light"] .card,
[data-theme="light"] .project-card,
[data-theme="light"] .exp-item {
  border-color: transparent;
  box-shadow: 0 1px 4px rgba(0,0,0,0.07), 0 0 0 1px rgba(0,0,0,0.04);
}

[data-theme="light"] .card:hover,
[data-theme="light"] .project-card:hover,
[data-theme="light"] .exp-item:hover {
  border-color: transparent;
  box-shadow: 0 4px 18px rgba(0,0,0,0.1), 0 0 0 1px rgba(0,0,0,0.05);
}

/* Tags — white fill in light mode so they lift off the grey bg */
[data-theme="light"] .tag {
  background: var(--surface);
}

/* =========================================
   Reset & Base
   ========================================= */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  color: var(--text-1);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

ul { list-style: none; }

/* =========================================
   Stars Canvas
   ========================================= */
#stars {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}

/* =========================================
   Navigation
   ========================================= */
#nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-h);
  z-index: 100;
  background: rgba(10, 10, 10, 0.78);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  height: 100%;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  position: relative;
}


.nav-links {
  display: flex;
  gap: 32px;
  align-items: center;
}

.nav-links a {
  font-size: 0.82rem;
  color: var(--text-3);
  letter-spacing: 0.05em;
  position: relative;
  padding-bottom: 2px;
  transition: color 0.2s;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 1px;
  background: var(--text-1);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-1);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  transform: scaleX(1);
}

/* — Right side nav wrapper — */
.nav-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* — Theme toggle — */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  background: #111111;
  border: 1px solid #2a2a2a;
  border-radius: 50%;
  cursor: pointer;
  color: var(--text-3);
  flex-shrink: 0;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

.theme-toggle:hover {
  background: #1e1e1e;
  border-color: #3a3a3a;
  color: var(--text-1);
}

.theme-toggle svg {
  width: 14px;
  height: 14px;
}

#icon-moon                         { display: none; }
[data-theme="light"] #icon-sun     { display: none; }
[data-theme="light"] #icon-moon    { display: block; }

/* Sun — yellow tint */
.theme-toggle #icon-sun {
  color: #fbbf24;
  stroke: #fbbf24;
}

/* Moon button — dark background in light theme so it pops against white */
[data-theme="light"] .theme-toggle {
  background: #111827;
  border-color: #111827;
  color: #c9d6e8;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

[data-theme="light"] .theme-toggle:hover {
  background: #1f2937;
  border-color: #1f2937;
  color: #f1f5f9;
}

/* — Hamburger — */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px 4px;
  z-index: 10;
}

.hamburger span {
  display: block;
  width: 20px;
  height: 1px;
  background: var(--text-2);
  transition: transform 0.28s ease, opacity 0.28s ease;
}

.hamburger.open span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.open span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* =========================================
   Section Common
   ========================================= */
section {
  padding: var(--pad-section) 28px;
  scroll-margin-top: var(--nav-h);
}

.section-inner {
  max-width: var(--max-w);
  margin: 0 auto;
}


.section-label {
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: 52px;
}

/* =========================================
   Reveal Animation
   ========================================= */
.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition:
    opacity  0.65s ease,
    transform 0.65s ease;
  transition-delay: var(--delay, 0ms);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================
   Hero / About
   ========================================= */
#about {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding-top: calc(var(--nav-h) + 48px);
  position: relative;
}

/* Avatar left, centred content right — the whole row is centred by #about */
.hero-outer {
  display: flex;
  align-items: center;
  gap: 52px;
  width: 100%;
  max-width: 920px;
}

.avatar {
  display: none;
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--border-hover);
  flex-shrink: 0;
  filter: blur(0.4px) contrast(0.94) saturate(0.95);
}

.has-avatar .avatar {
  display: block;
}

.hero-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

#about h1 {
  font-size: clamp(2rem, 5.5vw, 3.8rem);
  font-weight: 300;
  letter-spacing: -0.025em;
  line-height: 1.1;
  margin-bottom: 18px;
  color: var(--text-1);
}

.hero-affiliation {
  font-size: 0.82rem;
  color: var(--text-2);
  letter-spacing: 0.04em;
  margin-bottom: 12px;
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  margin-bottom: 24px;
}

/* Tags in about hero — brighter so they read against dark bg */
.hero-tags .tag {
  color: var(--text-2);
  border-color: var(--border-hover);
}

.hero-bio {
  font-size: 0.97rem;
  color: var(--text-2);
  line-height: 1.85;
  margin-bottom: 32px;
  max-width: 540px;
}

/* — CV download button — */
.hero-ctas {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-bottom: 32px;
}

.cv-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--text-1);
  border: 1px solid var(--border-hover);
  border-radius: 6px;
  padding: 9px 22px;
  transition: background 0.2s, border-color 0.2s, transform 0.2s;
}

.cv-btn svg {
  width: 14px;
  height: 14px;
  color: var(--text-3);
}

.cv-btn:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: var(--text-2);
  transform: translateY(-1px);
}

[data-theme="light"] .cv-btn:hover {
  background: rgba(0, 0, 0, 0.04);
}

.social-row {
  display: flex;
  gap: 14px;
  justify-content: center;
}

.social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--border);
  border-radius: 50%;
  color: var(--text-3);
  transition: color 0.2s, border-color 0.2s;
}

.social-link:hover {
  color: var(--text-1);
  border-color: var(--border-hover);
}

.social-link svg {
  width: 16px;
  height: 16px;
}

.scroll-hint {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-3);
  animation: bounce 2.4s ease-in-out infinite;
}

.scroll-hint svg {
  width: 18px;
  height: 18px;
}

@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); opacity: 0.4; }
  50%       { transform: translateX(-50%) translateY(7px); opacity: 0.8; }
}

/* =========================================
   Education
   ========================================= */
.edu-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

/* =========================================
   Cards (shared)
   ========================================= */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: border-color 0.25s ease, transform 0.25s ease;
}

.card:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.card-degree {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-1);
  line-height: 1.3;
}

.card-date {
  font-size: 0.75rem;
  color: var(--text-3);
  white-space: nowrap;
  padding-top: 2px;
  letter-spacing: 0.03em;
}

.card-inst {
  font-size: 0.83rem;
  color: var(--text-2);
}

.card-thesis {
  font-size: 0.84rem;
  color: var(--text-2);
  line-height: 1.6;
  font-style: italic;
}

.thesis-label {
  font-style: normal;
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-3);
  margin-right: 8px;
}

.card-supervisor {
  font-size: 0.78rem;
  color: var(--text-3);
  letter-spacing: 0.02em;
}

.metric {
  color: var(--text-1);
  font-weight: 500;
}

.card-desc {
  font-size: 0.86rem;
  color: var(--text-2);
  line-height: 1.75;
  text-align: justify;
}

.badge-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* =========================================
   Tags & Badges
   ========================================= */
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  font-size: 0.71rem;
  color: var(--text-3);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 3px 9px;
  letter-spacing: 0.03em;
}

.badge {
  font-size: 0.71rem;
  color: var(--text-2);
  border: 1px solid var(--border-hover);
  border-radius: 4px;
  padding: 3px 9px;
  letter-spacing: 0.03em;
}

.badge-solid {
  font-size: 0.71rem;
  color: var(--text-1);
  border: 1px solid var(--border-hover);
  border-radius: 4px;
  padding: 3px 9px;
  letter-spacing: 0.04em;
  background: rgba(255,255,255,0.04);
}

/* =========================================
   Experience
   ========================================= */
.exp-group {
  margin-bottom: 0;
}

.exp-role {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-1);
  margin-bottom: 28px;
}

.exp-items {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.exp-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: border-color 0.25s ease, transform 0.25s ease;
}

.exp-item:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.exp-item-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
}

.exp-inst {
  font-size: 0.87rem;
  color: var(--text-2);
  line-height: 1.5;
}

.exp-date {
  font-size: 0.75rem;
  color: var(--text-3);
  white-space: nowrap;
  letter-spacing: 0.02em;
  padding-top: 1px;
}

.exp-desc {
  font-size: 0.84rem;
  color: var(--text-2);
  line-height: 1.75;
  text-align: justify;
}

.exp-event {
  color: var(--text-1);
  font-weight: 600;
}


.exp-divider {
  height: 1px;
  background: var(--border);
  margin: 52px 0;
}

/* =========================================
   Projects
   ========================================= */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

.project-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: border-color 0.25s ease, transform 0.25s ease;
  cursor: pointer;
}

.project-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-3px);
}

.gh-icon {
  width: 18px;
  height: 18px;
  color: var(--text-3);
  flex-shrink: 0;
}

.project-card h3 {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-1);
  line-height: 1.4;
}

.project-card p {
  font-size: 0.83rem;
  color: var(--text-2);
  line-height: 1.75;
  flex: 1;
  text-align: justify;
}

/* =========================================
   Research Interests
   ========================================= */
.research-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.research-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 30px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: border-color 0.25s ease, transform 0.25s ease;
}

.research-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.research-icon {
  width: 36px;
  height: 36px;
  color: var(--text-3);
  flex-shrink: 0;
}

.research-icon svg {
  width: 100%;
  height: 100%;
}

.research-card h3 {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-1);
  line-height: 1.3;
}

.research-card p {
  font-size: 0.84rem;
  color: var(--text-2);
  line-height: 1.75;
}

/* =========================================
   Skills
   ========================================= */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 36px 48px;
}

.skill-group {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.skill-cat {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-2);
  letter-spacing: 0.06em;
}

/* Skills tags brighter in dark mode */
#skills .tag {
  color: var(--text-2);
}

/* Tighten gaps between specific section pairs */
#experience { padding-top: 48px; }
#projects   { padding-top: 48px; }

/* =========================================
   Certificates
   ========================================= */
.cert-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.cert-list li {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding-left: 20px;
  border-left: 1px solid var(--border);
}

.cert-list a {
  font-size: 0.87rem;
  color: var(--text-1);
  transition: color 0.2s;
  white-space: nowrap;
}

.cert-list a:hover {
  color: var(--text-2);
}

.cert-by {
  font-size: 0.75rem;
  color: var(--text-3);
  letter-spacing: 0.02em;
}

/* =========================================
   Footer
   ========================================= */
footer {
  padding: 48px 28px;
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-3);
  border-top: 1px solid var(--border);
  letter-spacing: 0.04em;
}

/* =========================================
   Responsive — Tablet / Mobile
   ========================================= */
@media (max-width: 768px) {
  :root { --pad-section: 60px; }

  .hamburger { display: flex; }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(10, 10, 10, 0.96);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    padding: 8px 0;
  }

  .nav-links.open { display: flex; }

  .nav-links li a {
    display: block;
    padding: 14px 28px;
    font-size: 0.88rem;
  }

  .nav-links a::after { display: none; }

  .edu-grid { grid-template-columns: 1fr; }

  .research-grid { grid-template-columns: 1fr; }

  .projects-grid { grid-template-columns: 1fr; }

  .skills-grid { grid-template-columns: 1fr; gap: 28px; }

  .card-header { flex-direction: column; gap: 6px; }

  .exp-item-head { flex-direction: column; gap: 4px; }

  /* Hero: stack avatar above centered content on mobile */
  .hero-outer {
    flex-direction: column;
    gap: 24px;
  }

  .has-avatar .avatar {
    width: 120px;
    height: 120px;
  }
}

@media (max-width: 480px) {
  :root { --pad-section: 48px; }

  #about h1 { font-size: 2rem; }

  .hero-bio { font-size: 0.9rem; }

  section { padding-left: 20px; padding-right: 20px; }

  .card { padding: 24px; }

  .project-card { padding: 22px; }
}