/* ===================================================
   CSS Custom Properties — Theme Tokens
   =================================================== */
:root {
  --bg: #0c0c0c;
  --bg-alt: #111111;
  --bg-card: #161616;
  --border: #2a2a2a;
  --text: #eeeeee;
  --text-muted: #a8a8a8;
  --text-faint: #606060;
  --accent: #eeeeee;
  --nav-bg: rgba(12, 12, 12, 0.85);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.6);
  --radius: 6px;
  --transition: 0.2s ease;
}

[data-theme="light"] {
  --bg: #fafafa;
  --bg-alt: #f2f2f2;
  --bg-card: #ffffff;
  --border: #e0e0e0;
  --text: #111111;
  --text-muted: #4a4a4a;
  --text-faint: #999999;
  --accent: #111111;
  --nav-bg: rgba(250, 250, 250, 0.88);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

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

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

body {
  font-family: "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  transition:
    background var(--transition),
    color var(--transition);
  -webkit-font-smoothing: antialiased;
}

.mono {
  font-family: "JetBrains Mono", "Fira Mono", monospace;
  font-size: 0.82em;
  letter-spacing: 0.02em;
}

img {
  max-width: 100%;
  display: block;
}
a {
  color: inherit;
  text-decoration: none;
}
ul {
  list-style: none;
}

/* ===================================================
   Layout
   =================================================== */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 6rem 0;
}

.section-alt {
  background: var(--bg-alt);
  transition: background var(--transition);
}

/* ===================================================
   Navigation
   =================================================== */
#navbar {
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 100;
  background: var(--nav-bg);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition:
    background var(--transition),
    border-color var(--transition);
}

.nav-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 56px;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-logo {
  font-family: "JetBrains Mono", monospace;
  font-weight: 500;
  font-size: 0.95rem;
  color: var(--text);
  letter-spacing: 0.08em;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  gap: 1.75rem;
  margin-left: auto;
  align-items: center;
}

.nav-links a {
  font-size: 0.84rem;
  color: var(--text-muted);
  transition: color var(--transition);
  font-weight: 450;
}

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

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  color: var(--text-muted);
  padding: 5px 7px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition:
    border-color var(--transition),
    color var(--transition);
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--text);
  border-color: var(--text-muted);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
}

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

.hamburger {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  margin-left: auto;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--text-muted);
  transition: var(--transition);
}

/* ===================================================
   Hero
   =================================================== */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.hero-grid-bg {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: 0.35;
  mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black, transparent);
  -webkit-mask-image: radial-gradient(
    ellipse 70% 60% at 50% 50%,
    black,
    transparent
  );
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 1;
  padding: 2rem 1.5rem;
}

.hero-label {
  color: var(--text-muted);
  margin-bottom: 0.6rem;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.hero-name {
  font-size: clamp(2.4rem, 6vw, 4.2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.08;
  margin-bottom: 1.2rem;
  color: var(--text);
}

.hero-callme {
  font-size: 0.78rem;
  color: var(--text-faint);
  margin-top: -0.5rem;
  margin-bottom: 1.6rem;
  letter-spacing: 0.02em;
}

.hero-callme-name {
  color: var(--text-muted);
  font-style: italic;
}

.hero-sub {
  font-size: 1.1rem;
  color: var(--text);
  line-height: 1.7;
  margin-bottom: 2.2rem;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
  font-weight: 500;
}

.hero-sub .hero-sub-spec {
  font-size: 0.97rem;
  color: var(--text-muted);
  font-weight: 400;
}

.hero-cta {
  display: flex;
  gap: 0.85rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  padding: 0.6rem 1.4rem;
  border-radius: var(--radius);
  font-size: 0.88rem;
  font-weight: 500;
  transition: all var(--transition);
  cursor: pointer;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}

.btn-primary:hover {
  opacity: 0.85;
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-outline:hover {
  border-color: var(--text-muted);
}

.hero-scroll-hint {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-faint);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.scroll-line {
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, var(--text-faint), transparent);
  animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
  0%,
  100% {
    opacity: 0.3;
    transform: scaleY(1);
  }
  50% {
    opacity: 0.9;
    transform: scaleY(0.7);
  }
}

/* ===================================================
   Section Titles
   =================================================== */
.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 3rem;
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  letter-spacing: -0.02em;
}

.section-num {
  color: var(--text-faint);
  font-size: 0.78rem;
}

/* ===================================================
   Reveal Animation
   =================================================== */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition:
    opacity 0.55s ease,
    transform 0.55s ease;
}

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

/* ===================================================
   About
   =================================================== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 240px;
  gap: 4rem;
  align-items: start;
}

.about-text p {
  color: var(--text-muted);
  margin-bottom: 1rem;
  font-size: 0.97rem;
}

.about-text p:last-child {
  margin-bottom: 0;
}

.about-text strong {
  color: var(--text);
  font-weight: 600;
}

.about-photo {
  display: flex;
  justify-content: center;
}

.photo-wrapper {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  overflow: hidden;
  border: 1px solid var(--border);
  flex-shrink: 0;
}

.photo-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
  filter: grayscale(20%);
}

/* ===================================================
   Experience / Timeline
   =================================================== */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.timeline-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 1.5rem;
  align-items: start;
}

.timeline-meta {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding-top: 1.25rem;
  text-align: right;
}

.timeline-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: border-color var(--transition);
}

.timeline-card:hover {
  border-color: var(--text-faint);
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
  gap: 1rem;
}

.timeline-header h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  letter-spacing: -0.01em;
}

.org {
  font-size: 0.83rem;
  color: var(--text-muted);
}

.dept-badge {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.68rem;
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 3px 8px;
  color: var(--text-muted);
  white-space: nowrap;
  flex-shrink: 0;
}

.bullet-list {
  padding-left: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.bullet-list li {
  font-size: 0.88rem;
  color: var(--text-muted);
  padding-left: 1.1rem;
  position: relative;
}

.bullet-list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--text-faint);
}

.bullet-list li strong {
  color: var(--text);
}

.tag {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.72rem;
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 2px 8px;
  color: var(--text-muted);
  white-space: nowrap;
  display: inline-block;
}

.tag-active {
  color: var(--text);
  border-color: var(--text-muted);
}

.edu-detail {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

.edu-detail strong { color: var(--text); }

.courses-label {
  color: var(--text-faint);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 1rem;
  margin-bottom: 0.4rem;
}

.edu-courses {
  font-size: 0.84rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ===================================================
   Projects
   =================================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color var(--transition);
}

.project-card:hover {
  border-color: var(--text-faint);
}

.project-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.project-icon svg {
  width: 24px;
  height: 24px;
  color: var(--text-muted);
}

.project-link {
  color: var(--text-faint);
  transition: color var(--transition);
}

.project-link:hover {
  color: var(--text);
}
.project-link svg {
  width: 16px;
  height: 16px;
}

.project-card h3 {
  font-size: 0.97rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.project-full-name {
  color: var(--text-faint);
  font-size: 0.72em;
  margin-top: -0.4rem;
}

.project-card p:not(.project-full-name) {
  font-size: 0.86rem;
  color: var(--text-muted);
  flex: 1;
}

.project-card p strong {
  color: var(--text);
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: auto;
}

/* ===================================================
   Research
   =================================================== */
.research-list {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.research-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  transition: border-color var(--transition);
}

.research-card:hover {
  border-color: var(--text-faint);
}

.research-venue {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.venue-badge {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.7rem;
  background: var(--border);
  padding: 2px 8px;
  border-radius: 3px;
  color: var(--text-muted);
}

.pub-date {
  color: var(--text-faint);
  font-size: 0.75rem;
}

.research-card h3 {
  font-size: 0.97rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
  line-height: 1.4;
  letter-spacing: -0.01em;
}

.journal-name {
  font-size: 0.82rem;
  color: var(--text-faint);
  margin-bottom: 0.75rem;
}

.research-card > p:not(.journal-name) {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.research-card p strong {
  color: var(--text);
}

.btn-text {
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: color var(--transition);
}

.btn-text:hover {
  color: var(--text);
}

/* ===================================================
   Skills
   =================================================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}

.skill-group h4 {
  font-size: 0.72rem;
  color: var(--text-faint);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.9rem;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* ===================================================
   Contact
   =================================================== */
.contact-container {
  text-align: center;
}

.contact-lead {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: 2.5rem;
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

.contact-link {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.88rem;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.55rem 1rem;
  transition:
    color var(--transition),
    border-color var(--transition);
}

.contact-link:hover {
  color: var(--text);
  border-color: var(--text-muted);
}

.contact-link svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

/* ===================================================
   Footer
   =================================================== */
footer {
  border-top: 1px solid var(--border);
  padding: 1.75rem 0;
  text-align: center;
  transition: border-color var(--transition);
}

footer p {
  font-size: 0.78rem;
  color: var(--text-faint);
}

/* ===================================================
   Responsive
   =================================================== */
@media (max-width: 768px) {
  .hamburger {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 56px;
    left: 0;
    width: 100%;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 1.25rem 1.5rem;
    gap: 1rem;
    align-items: flex-start;
  }

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

  .theme-toggle {
    margin-left: 0;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .about-photo {
    order: -1;
  }

  .photo-wrapper {
    width: 140px;
    height: 140px;
  }

  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .timeline-meta {
    flex-direction: row;
    align-items: center;
    padding-top: 0;
    text-align: left;
  }

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

  .skills-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

@media (max-width: 480px) {
  .section {
    padding: 4rem 0;
  }
  .hero-name {
    font-size: 2.2rem;
  }
}