/* ===== VARIABLES ===== */
:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #0f0f18;
  --bg-card: #141420;
  --text-primary: #e4e4e7;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --border: #27272a;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --nav-height: 70px;
  --container-width: 1100px;
  --transition: 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  color: var(--accent-hover);
}

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

/* ===== NAVBAR ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(10, 10, 15, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  z-index: 1000;
  transition: border-color var(--transition);
}

.navbar.scrolled {
  border-bottom-color: var(--border);
}

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

.nav-logo {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.nav-logo:hover { color: var(--text-primary); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.nav-links a:hover { color: var(--accent); }

.nav-resume-btn {
  padding: 0.4rem 1rem;
  border: 1px solid var(--accent);
  border-radius: 4px;
  color: var(--accent) !important;
}

.nav-resume-btn:hover {
  background: rgba(59, 130, 246, 0.1);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== HERO ===== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  padding: 0 2rem;
}

.hero-bg-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(59, 130, 246, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59, 130, 246, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse at center, black 20%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse at center, black 20%, transparent 70%);
}

.hero-content {
  max-width: var(--container-width);
  margin: 0 auto;
  z-index: 1;
}

.hero-greeting {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.hero-name {
  font-size: clamp(2.5rem, 7vw, 4.5rem);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 1rem;
}

.hero-tagline {
  font-size: clamp(0.95rem, 2.5vw, 1.15rem);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: 1.5rem;
}

.hero-description {
  max-width: 540px;
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 2rem;
}

.hero-links {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.4rem;
  border-radius: 4px;
  font-size: 0.875rem;
  font-weight: 500;
  font-family: var(--font-mono);
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  color: #fff;
}

.btn-secondary {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ===== SECTIONS ===== */
.section {
  padding: 6rem 2rem;
}

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

.container {
  max-width: var(--container-width);
  margin: 0 auto;
}

.section-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 3rem;
}

.accent { color: var(--accent); }

/* ===== ABOUT ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 3rem;
  align-items: start;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  font-size: 0.95rem;
}

.about-details {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.detail-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.detail-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.detail-value {
  font-weight: 600;
  font-size: 0.9rem;
}

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

/* ===== RESEARCH ===== */
.research-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.research-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  min-height: 380px;
}

.research-status {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  border: 1px solid var(--accent);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  margin-bottom: 1rem;
  width: fit-content;
}

.research-title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.research-authors {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.research-abstract p {
  color: var(--text-secondary);
  font-size: 0.88rem;
  margin-bottom: 0.5rem;
}

.abstract-expanded {
  display: none;
}

.abstract-expanded.show {
  display: block;
}

.abstract-toggle {
  background: none;
  border: none;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  cursor: pointer;
  padding: 0;
  margin-bottom: 1rem;
}

.abstract-toggle:hover {
  color: var(--accent-hover);
}

.research-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 1rem;
  margin-top: auto;
}

.research-tags span {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  background: rgba(255, 255, 255, 0.04);
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
  border: 1px solid var(--border);
}

.research-link {
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

/* ===== PROJECTS ===== */
.projects-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  min-height: 320px;
}

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

.project-title {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.3;
}

.project-gh {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
  white-space: nowrap;
  flex-shrink: 0;
}

.project-gh:hover {
  color: var(--accent);
}

.project-description {
  color: var(--text-secondary);
  font-size: 0.88rem;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

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

.project-tech span {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
}

/* ===== SKILLS ===== */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.skill-category h3 {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  margin-bottom: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.skill-tags span {
  background: var(--bg-card);
  border: 1px solid var(--border);
  padding: 0.4rem 0.9rem;
  border-radius: 4px;
  font-size: 0.82rem;
  color: var(--text-secondary);
}

/* ===== ACHIEVEMENTS ===== */
.achievements-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.achievement-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.75rem;
  min-height: 220px;
  display: flex;
  flex-direction: column;
}

.achievement-card h3 {
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

.achievement-card p {
  color: var(--text-secondary);
  font-size: 0.85rem;
}

/* ===== CONTACT ===== */
.contact-container {
  text-align: center;
  max-width: 550px;
}

.contact-text {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 2rem;
}

.contact-links {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== FOOTER ===== */
.footer {
  padding: 2.5rem 2rem;
  text-align: center;
  border-top: 1px solid var(--border);
}

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

/* ===== ANIMATIONS ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }
  .projects-grid { grid-template-columns: 1fr; }
  .research-grid { grid-template-columns: 1fr; }
  .achievements-grid { grid-template-columns: 1fr; }
  .skills-grid { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(10, 10, 15, 0.97);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 2rem;
    gap: 1.5rem;
    border-bottom: 1px solid var(--border);
    transform: translateY(-110%);
    transition: transform var(--transition);
  }

  .nav-links.open { transform: translateY(0); }
  .nav-toggle { display: flex; }

  .nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  .nav-toggle.active span:nth-child(2) { opacity: 0; }
  .nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

  .section { padding: 4rem 1.25rem; }

  .hero-links { flex-direction: column; }
  .hero-links .btn { justify-content: center; }

  .project-card { min-height: auto; }
  .research-card { min-height: auto; }
  .achievement-card { min-height: auto; }
}