/* ─────────────────────────────────────────
   Variables & Reset
───────────────────────────────────────── */
:root {
  --bg:          #0d1117;
  --bg2:         #161b22;
  --bg3:         #21262d;
  --border:      #30363d;
  --text:        #e6edf3;
  --text-muted:  #8b949e;
  --green:       #3fb950;
  --green-dim:   rgba(63, 185, 80, 0.12);
  --green-glow:  rgba(63, 185, 80, 0.06);
  --blue:        #58a6ff;
  --orange:      #e3b341;

  --sans:  'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono:  'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  --nav-h:  64px;
  --max-w:  1100px;
  --radius: 8px;
  --transition: 0.2s ease;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

.mono { font-family: var(--mono); }
.accent { color: var(--green); }

/* ─────────────────────────────────────────
   Utility
───────────────────────────────────────── */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
}

section {
  padding: 100px 0;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 3rem;
}

.section-num {
  color: var(--green);
  font-size: 0.85rem;
  letter-spacing: 0.05em;
}

.section-header h2 {
  font-size: clamp(1.5rem, 3vw, 1.9rem);
  font-weight: 600;
  white-space: nowrap;
}

.section-rule {
  flex: 1;
  height: 1px;
  background: var(--border);
  max-width: 320px;
}

/* ─────────────────────────────────────────
   Buttons
───────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.4rem;
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn .icon { width: 16px; height: 16px; }

.btn-primary {
  background: var(--green);
  color: #0d1117;
  border: 1px solid var(--green);
}
.btn-primary:hover {
  background: #4cc963;
  border-color: #4cc963;
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--green);
  border: 1px solid var(--green);
}
.btn-secondary:hover {
  background: var(--green-dim);
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}
.btn-ghost:hover {
  color: var(--text);
  border-color: var(--text-muted);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--green);
  border: 1px solid var(--green);
  margin-top: 2.5rem;
}
.btn-outline:hover {
  background: var(--green-dim);
  transform: translateY(-1px);
}

/* ─────────────────────────────────────────
   Navigation
───────────────────────────────────────── */
#navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  z-index: 100;
  transition: background var(--transition), box-shadow var(--transition);
}

#navbar.scrolled {
  background: rgba(13, 17, 23, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--border);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--mono);
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--green);
  letter-spacing: -0.02em;
  transition: opacity var(--transition);
}
.nav-logo:hover { opacity: 0.8; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-links a {
  padding: 0.4rem 0.75rem;
  font-size: 0.825rem;
  color: var(--text-muted);
  border-radius: 6px;
  transition: all var(--transition);
}
.nav-links a:hover { color: var(--text); background: var(--bg3); }
.nav-num { color: var(--green); font-family: var(--mono); margin-right: 0.2rem; font-size: 0.75rem; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--text-muted);
  border-radius: 2px;
  transition: all 0.3s ease;
}

/* ─────────────────────────────────────────
   Hero
───────────────────────────────────────── */
#hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 2rem;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.dot-grid {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 1px 1px, rgba(255,255,255,0.06) 1px, transparent 0);
  background-size: 36px 36px;
}

.hero-glow {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 60% at 50% 40%, rgba(63, 185, 80, 0.06) 0%, transparent 70%);
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 800px;
}

.hero-eyebrow {
  font-size: 0.8rem;
  color: var(--green);
  letter-spacing: 0.08em;
  margin-bottom: 1.5rem;
  opacity: 0;
  animation: fadeUp 0.6s ease 0.2s forwards;
}

.hero-name {
  font-size: clamp(3.5rem, 10vw, 6.5rem);
  font-weight: 700;
  line-height: 1.0;
  letter-spacing: -0.03em;
  margin-bottom: 1.75rem;
  opacity: 0;
  animation: fadeUp 0.6s ease 0.4s forwards;
}

.hero-terminal {
  display: inline-flex;
  align-items: center;
  gap: 0;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.6rem 1.1rem;
  font-size: clamp(0.75rem, 2vw, 0.9rem);
  margin-bottom: 2.5rem;
  opacity: 0;
  animation: fadeUp 0.6s ease 0.6s forwards;
}

.prompt { color: var(--text-muted); margin-right: 0.1rem; }
#typedText { color: var(--text); min-width: 1px; }

.cursor {
  color: var(--green);
  animation: blink 1s step-end infinite;
  font-family: var(--mono);
  font-size: 0.9rem;
  margin-left: 1px;
}

.hero-cta {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  opacity: 0;
  animation: fadeUp 0.6s ease 0.8s forwards;
}

.hero-cta .btn .icon { width: 15px; height: 15px; }

.hero-scroll {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-muted);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  opacity: 0;
  animation: fadeUp 0.6s ease 1.2s forwards;
}

.scroll-line {
  width: 1px;
  height: 48px;
  background: linear-gradient(to bottom, var(--text-muted), transparent);
  animation: scrollDrop 2s ease-in-out infinite;
}

/* ─────────────────────────────────────────
   About
───────────────────────────────────────── */
#about { background: var(--bg); }

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-text p {
  color: var(--text-muted);
  margin-bottom: 1.1rem;
  font-size: 0.975rem;
  max-width: 520px;
}

.about-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1.75rem;
}

.about-tags li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.825rem;
  color: var(--text-muted);
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.3rem 0.75rem;
  transition: all var(--transition);
}
.about-tags li:hover {
  border-color: var(--green);
  color: var(--text);
}

.tag-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--green);
  flex-shrink: 0;
}

.about-terminal {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.terminal-titlebar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1rem;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
}

.t-dots { display: flex; gap: 6px; }
.t-dot {
  width: 12px; height: 12px;
  border-radius: 50%;
}
.t-dot.red    { background: #ff5f57; }
.t-dot.yellow { background: #febc2e; }
.t-dot.green  { background: #28c840; }

.t-name {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-left: auto;
  margin-right: auto;
  padding-right: 60px;
}

.terminal-body {
  padding: 1.25rem 1.5rem;
  font-size: 0.82rem;
  line-height: 1.75;
  overflow-x: auto;
}

.j-key    { color: var(--blue); }
.j-str    { color: var(--green); }
.j-bool   { color: var(--orange); }
.j-brace  { color: var(--text-muted); }
.j-colon  { color: var(--text-muted); }
.j-comma  { color: var(--text-muted); }

/* ─────────────────────────────────────────
   Skills
───────────────────────────────────────── */
#skills { background: var(--bg2); }

.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}

.skill-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: border-color var(--transition), transform var(--transition);
}
.skill-card:hover {
  border-color: var(--green);
  transform: translateY(-2px);
}

.skill-card-top {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.1rem;
}

.skill-icon {
  color: var(--green);
  font-size: 1.1rem;
}

.skill-card h3 {
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--text);
}

.skill-card ul li {
  font-size: 0.825rem;
  color: var(--text-muted);
  padding: 0.3rem 0;
  border-bottom: 1px solid rgba(48,54,61,0.5);
  transition: color var(--transition);
}
.skill-card ul li:last-child { border-bottom: none; }
.skill-card:hover ul li { color: var(--text); }

.cert-list li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.cert-badge {
  font-family: var(--mono);
  font-size: 0.7rem;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-weight: 500;
}
.cert-badge.active   { background: var(--green-dim); color: var(--green); border: 1px solid rgba(63,185,80,0.3); }
.cert-badge.wip      { background: rgba(227,179,65,0.1); color: var(--orange); border: 1px solid rgba(227,179,65,0.3); }
.cert-badge.upcoming { background: rgba(88,166,255,0.1); color: var(--blue); border: 1px solid rgba(88,166,255,0.3); }

/* ─────────────────────────────────────────
   Projects
───────────────────────────────────────── */
#projects { background: var(--bg); }

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

.projects-grid .project-card:nth-child(n+3) {
  /* smaller cards after the 2 featured */
}

.project-card {
  background: var(--bg2);
  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), transform var(--transition);
}
.project-card:hover {
  border-color: var(--green);
  transform: translateY(-3px);
}

.project-card.featured {
  border-color: rgba(63,185,80,0.2);
}

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

.project-folder {
  width: 36px; height: 36px;
  color: var(--green);
}

.project-ext-links {
  display: flex;
  gap: 0.75rem;
}
.project-ext-links a {
  color: var(--text-muted);
  transition: color var(--transition);
}
.project-ext-links a:hover { color: var(--green); }
.project-ext-links svg { width: 18px; height: 18px; }

.project-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  transition: color var(--transition);
}
.project-card:hover .project-title { color: var(--green); }

.project-desc {
  font-size: 0.845rem;
  color: var(--text-muted);
  line-height: 1.6;
  flex: 1;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: auto;
}

.tag {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--green);
  background: var(--green-dim);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
}

.projects-footer { text-align: center; }

.projects-sublabel {
  font-size: 0.78rem;
  color: var(--green);
  letter-spacing: 0.06em;
  margin-bottom: 1.25rem;
}

/* Research paper cards */
.papers-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.paper-card {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  transition: border-color var(--transition), transform var(--transition);
  cursor: pointer;
}
.paper-card:hover {
  border-color: rgba(88,166,255,0.4);
  transform: translateY(-2px);
}

.paper-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.paper-icon { color: var(--blue); font-size: 1rem; }

.paper-link-icon {
  width: 14px; height: 14px;
  color: var(--text-muted);
  transition: color var(--transition);
}
.paper-card:hover .paper-link-icon { color: var(--blue); }

.paper-card h4 {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
  line-height: 1.4;
  transition: color var(--transition);
}
.paper-card:hover h4 { color: var(--blue); }

.paper-card p {
  font-size: 0.795rem;
  color: var(--text-muted);
  line-height: 1.55;
  flex: 1;
}

.paper-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.paper-tags .tag {
  color: var(--blue);
  background: rgba(88,166,255,0.1);
}

/* ─────────────────────────────────────────
   Resume
───────────────────────────────────────── */
#resume { background: var(--bg2); }

.resume-cols {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.resume-group { margin-bottom: 2.5rem; }
.resume-group:last-child { margin-bottom: 0; }

.resume-group-title {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.resume-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
}
.resume-item:last-child { border-bottom: none; }

.resume-item-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.25rem;
}

.resume-item-head h4 {
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--text);
}

.resume-date {
  font-size: 0.75rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.badge-wip {
  color: var(--orange);
  background: rgba(227,179,65,0.1);
  border: 1px solid rgba(227,179,65,0.25);
  border-radius: 4px;
  padding: 0.1rem 0.45rem;
}

.resume-org {
  font-size: 0.825rem;
  color: var(--green);
  margin-bottom: 0.5rem;
}

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

.resume-bullets {
  list-style: none;
  margin-top: 0.5rem;
}
.resume-bullets li {
  font-size: 0.825rem;
  color: var(--text-muted);
  padding: 0.2rem 0;
  padding-left: 1rem;
  position: relative;
}
.resume-bullets li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--green);
  font-size: 0.7rem;
  top: 0.3rem;
}

.resume-download {
  display: flex;
  justify-content: center;
  margin-top: 3rem;
}

/* ─────────────────────────────────────────
   Contact
───────────────────────────────────────── */
#contact { background: var(--bg); }

.contact-wrap { max-width: 640px; }

.contact-intro {
  font-size: 0.975rem;
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  max-width: 480px;
}

.contact-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  padding: 1rem 1.25rem;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all var(--transition);
}
.contact-item:hover {
  border-color: var(--green);
  transform: translateX(4px);
}

.contact-icon-wrap {
  width: 40px; height: 40px;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg3);
  border-radius: 8px;
  flex-shrink: 0;
}
.contact-icon-wrap svg { width: 18px; height: 18px; color: var(--green); }

.contact-text {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  flex: 1;
}

.contact-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

.contact-value {
  font-size: 0.875rem;
  color: var(--text);
}

.contact-arrow {
  width: 16px; height: 16px;
  color: var(--text-muted);
  transition: color var(--transition), transform var(--transition);
}
.contact-item:hover .contact-arrow {
  color: var(--green);
  transform: translateX(3px);
}

/* ─────────────────────────────────────────
   Footer
───────────────────────────────────────── */
footer {
  background: var(--bg2);
  border-top: 1px solid var(--border);
  padding: 2.5rem 0;
  text-align: center;
}

.footer-brand {
  font-size: 1rem;
  color: var(--green);
  margin-bottom: 0.4rem;
}

.footer-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ─────────────────────────────────────────
   Animations
───────────────────────────────────────── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0; }
}

@keyframes scrollDrop {
  0%   { transform: scaleY(0); transform-origin: top; }
  50%  { transform: scaleY(1); transform-origin: top; }
  51%  { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ─────────────────────────────────────────
   Responsive
───────────────────────────────────────── */
@media (max-width: 900px) {
  .about-grid   { grid-template-columns: 1fr; gap: 2.5rem; }
  .skills-grid  { grid-template-columns: repeat(2, 1fr); }
  .projects-grid { grid-template-columns: 1fr; }
  .papers-grid   { grid-template-columns: 1fr; }
  .resume-cols  { grid-template-columns: 1fr; gap: 0; }
}

@media (max-width: 640px) {
  section { padding: 72px 0; }
  .skills-grid { grid-template-columns: 1fr; }

  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-h);
    left: 0; right: 0;
    background: rgba(13,17,23,0.97);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 1.5rem 2rem;
    gap: 0.25rem;
    border-bottom: 1px solid var(--border);
  }
  .nav-links.open { display: flex; }
  .nav-links a { font-size: 0.95rem; padding: 0.6rem 0; }
  .nav-toggle { display: flex; }

  .hero-cta { flex-direction: column; align-items: center; }
  .hero-terminal { font-size: 0.72rem; padding: 0.5rem 0.85rem; }
}