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

:root {
  --bg:       #0d1117;
  --bg2:      #161b22;
  --bg3:      #1c2128;
  --border:   #30363d;
  --text:     #e6edf3;
  --muted:    #8b949e;
  --accent:   #4F8EF7;
  --accent2:  #79c0ff;
  --green:    #3fb950;
  --radius:   8px;
  --font:     'Inter', system-ui, sans-serif;
  --mono:     'JetBrains Mono', 'Courier New', monospace;
  --max:      1100px;
}

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent2); text-decoration: none; }
a:hover { color: var(--accent); }

/* ===== LAYOUT ===== */
.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

section { padding: 96px 0; }

.section-title {
  font-family: var(--mono);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 48px;
}
.section-title::before { content: '// '; opacity: 0.4; }

/* ===== NAV ===== */
#nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 0 24px;
  transition: background 0.3s, backdrop-filter 0.3s, border-color 0.3s;
  border-bottom: 1px solid transparent;
}
#nav.scrolled {
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom-color: var(--border);
}

.nav-inner {
  max-width: var(--max);
  margin: 0 auto;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--mono);
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--text);
  letter-spacing: 0.05em;
}
.nav-logo:hover { color: var(--accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}
.nav-links a {
  font-size: 0.875rem;
  color: var(--muted);
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--text); }

.nav-cta {
  background: var(--accent) !important;
  color: #fff !important;
  padding: 7px 18px;
  border-radius: var(--radius);
  font-weight: 500;
  transition: opacity 0.2s !important;
}
.nav-cta:hover { opacity: 0.85; color: #fff !important; }

.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);
  border-radius: 2px;
  transition: transform 0.3s;
}

/* ===== HERO ===== */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding: 120px 24px 80px;
}

.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: 60px 60px;
  opacity: 0.25;
  animation: gridpulse 8s ease-in-out infinite;
}
@keyframes gridpulse {
  0%, 100% { opacity: 0.2; }
  50% { opacity: 0.3; }
}

.hero-inner {
  max-width: var(--max);
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-tag {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 20px;
}

#hero h1 {
  font-family: var(--mono);
  font-size: clamp(2.8rem, 7vw, 5.5rem);
  font-weight: 600;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 24px;
}
#hero h1 .accent { color: var(--accent); }

.hero-sub {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--muted);
  max-width: 520px;
  margin-bottom: 40px;
  line-height: 1.7;
}

.hero-ctas {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.9rem;
  transition: opacity 0.2s, transform 0.2s;
}
.btn-primary:hover { opacity: 0.88; transform: translateY(-1px); color: #fff; }

.btn-secondary {
  border: 1px solid var(--border);
  color: var(--text);
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 500;
  font-size: 0.9rem;
  transition: border-color 0.2s, transform 0.2s;
}
.btn-secondary:hover { border-color: var(--accent); color: var(--text); transform: translateY(-1px); }

/* ===== ABOUT ===== */
#about { background: var(--bg2); }

.about-grid {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 64px;
  align-items: start;
}

.about-text p {
  color: var(--muted);
  margin-bottom: 20px;
  font-size: 1.05rem;
  line-height: 1.75;
}
.about-text p:last-child { margin-bottom: 0; }

.about-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.stat {
  background: var(--bg3);
  padding: 20px 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.stat-num {
  font-family: var(--mono);
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--accent);
  line-height: 1;
}

.stat-label {
  font-size: 0.75rem;
  color: var(--muted);
  line-height: 1.3;
}

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

.card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color 0.2s, transform 0.2s;
}
.card:hover {
  border-color: rgba(79, 142, 247, 0.4);
  transform: translateY(-3px);
}

.card-featured {
  grid-column: 1 / -1;
  border-color: rgba(79, 142, 247, 0.3);
  background: linear-gradient(135deg, var(--bg2) 0%, rgba(79, 142, 247, 0.04) 100%);
}
.card-featured:hover { border-color: rgba(79, 142, 247, 0.6); }

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.card-tag {
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--accent);
  background: rgba(79, 142, 247, 0.1);
  border: 1px solid rgba(79, 142, 247, 0.25);
  padding: 3px 10px;
  border-radius: 20px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.card-links {
  display: flex;
  gap: 16px;
}
.card-links a {
  font-size: 0.8rem;
  color: var(--muted);
  transition: color 0.2s;
}
.card-links a:hover { color: var(--accent2); }

.card h3 {
  font-family: var(--mono);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 10px;
}

.card > p {
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.65;
  margin-bottom: 20px;
}

.metrics {
  display: flex;
  gap: 24px;
  margin-bottom: 20px;
  padding: 16px;
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.metric { display: flex; flex-direction: column; gap: 2px; }
.metric-val {
  font-family: var(--mono);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--green);
}
.metric-label { font-size: 0.75rem; color: var(--muted); }

.card-bullets {
  list-style: none;
  margin-bottom: 20px;
}
.card-bullets li {
  font-size: 0.875rem;
  color: var(--muted);
  padding: 4px 0 4px 16px;
  position: relative;
  line-height: 1.5;
}
.card-bullets li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-size: 0.8rem;
}

.tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.tech-tags span {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--muted);
  background: var(--bg3);
  border: 1px solid var(--border);
  padding: 3px 10px;
  border-radius: 4px;
}

/* ===== RESEARCH ===== */
#research { background: var(--bg2); }

.research-meta {
  display: flex;
  align-items: center;
  gap: 32px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}

.research-stat {
  font-size: 0.9rem;
  color: var(--muted);
}
.research-stat span {
  font-family: var(--mono);
  font-weight: 600;
  color: var(--text);
}

.scholar-link {
  margin-left: auto;
  font-size: 0.85rem;
  color: var(--accent);
  border: 1px solid rgba(79, 142, 247, 0.3);
  padding: 6px 16px;
  border-radius: var(--radius);
  transition: background 0.2s;
}
.scholar-link:hover { background: rgba(79, 142, 247, 0.08); color: var(--accent); }

.eu-projects {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.eu-label {
  font-size: 0.75rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-right: 4px;
}

.eu-tag {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--accent2);
  background: rgba(121, 192, 255, 0.08);
  border: 1px solid rgba(121, 192, 255, 0.2);
  padding: 4px 12px;
  border-radius: 20px;
}

.pubs {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-bottom: 56px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.pub {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border);
  transition: background 0.15s;
}
.pub:last-child { border-bottom: none; }
.pub:hover { background: var(--bg3); }

.pub-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 6px;
}

.pub-venue {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--accent);
}

.pub-cites {
  font-size: 0.75rem;
  color: var(--green);
  background: rgba(63, 185, 80, 0.08);
  border: 1px solid rgba(63, 185, 80, 0.2);
  padding: 2px 8px;
  border-radius: 20px;
}

.pub h4 {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
  line-height: 1.5;
}
.pub h4 a { color: var(--text); transition: color 0.15s; }
.pub h4 a:hover { color: var(--accent2); }

.service { }
.service h3 {
  font-family: var(--mono);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 24px;
}

.service-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.service-grid > div {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}

.service-grid h4 {
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.service-grid p {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.6;
}

/* ===== STACK ===== */
.stack-groups {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.stack-group {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}

.stack-group h4 {
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 16px;
}

.stack-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.stack-pills span {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--text);
  background: var(--bg3);
  border: 1px solid var(--border);
  padding: 5px 14px;
  border-radius: 20px;
  transition: border-color 0.15s, color 0.15s;
}
.stack-pills span:hover {
  border-color: rgba(79, 142, 247, 0.4);
  color: var(--accent2);
}

/* ===== CONTACT ===== */
#contact { background: var(--bg2); text-align: center; }

.contact-sub {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 540px;
  margin: 0 auto 48px;
  line-height: 1.7;
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

.contact-link {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 10px 20px;
  border-radius: var(--radius);
  font-size: 0.875rem;
  transition: color 0.2s, border-color 0.2s, transform 0.2s;
}
.contact-link:hover {
  color: var(--text);
  border-color: rgba(79, 142, 247, 0.4);
  transform: translateY(-2px);
}

/* ===== FOOTER ===== */
footer {
  padding: 32px 24px;
  border-top: 1px solid var(--border);
  text-align: center;
}
footer p {
  font-size: 0.8rem;
  color: var(--muted);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 860px) {
  .about-grid { grid-template-columns: 1fr; }
  .about-stats { grid-template-columns: repeat(4, 1fr); }
  .projects-grid { grid-template-columns: 1fr; }
  .card-featured { grid-column: 1; }
  .stack-groups { grid-template-columns: 1fr; }
  .service-grid { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  section { padding: 72px 0; }
  #hero h1 { font-size: 2.4rem; }
  .about-stats { grid-template-columns: 1fr 1fr; }
  .nav-toggle { display: flex; }
  .nav-links {
    display: none;
    position: fixed;
    top: 60px; left: 0; right: 0;
    background: var(--bg2);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 8px 0;
  }
  .nav-links.open { display: flex; }
  .nav-links li { width: 100%; }
  .nav-links a {
    display: block;
    padding: 12px 24px;
    font-size: 1rem;
  }
  .nav-cta {
    margin: 8px 24px;
    padding: 10px 18px !important;
    text-align: center;
    border-radius: var(--radius) !important;
  }
  .research-meta { gap: 16px; }
  .scholar-link { margin-left: 0; }
}