/* ============================================
   MD SHOHANUR RAHMAN — PORTFOLIO
   Design: Deep navy + electric cyan + cream
   Typefaces: Space Grotesk (UI) · Fraunces (display) · JetBrains Mono (code/data)
   ============================================ */

:root {
  --navy:       #0B1120;
  --navy-mid:   #111827;
  --navy-light: #1E2D45;
  --cyan:       #00D4FF;
  --cyan-dim:   rgba(0, 212, 255, 0.12);
  --cyan-glow:  rgba(0, 212, 255, 0.25);
  --cream:      #F5F0E8;
  --white:      #FFFFFF;
  --muted:      #8DA0B5;
  --border:     rgba(255,255,255,0.08);
  --card-bg:    rgba(30, 45, 69, 0.6);

  --font-display: 'Fraunces', Georgia, serif;
  --font-ui:      'Space Grotesk', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', 'Courier New', monospace;

  --radius:     12px;
  --radius-sm:  6px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--navy);
  color: var(--cream);
  font-family: var(--font-ui);
  font-size: 16px;
  line-height: 1.7;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; }

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* ── NAV ─────────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2.5rem;
  background: rgba(11,17,32,0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-logo {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 500;
  color: var(--cyan);
  letter-spacing: 0.15em;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: 0.03em;
  transition: color var(--transition);
}

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

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--cream);
  font-size: 1.4rem;
  cursor: pointer;
}

/* ── HERO ─────────────────────────────── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 3rem;
  padding: 8rem 2.5rem 4rem;
  max-width: 1100px;
  margin: 0 auto;
  position: relative;
}

.hero-bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,212,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,212,255,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: -1;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  background: var(--cyan-dim);
  border: 1px solid rgba(0,212,255,0.3);
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
  letter-spacing: 0.05em;
}

.dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.8); }
}

.hero-name {
  font-family: var(--font-display);
  font-size: clamp(3rem, 7vw, 5.5rem);
  font-weight: 600;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--white);
  margin-bottom: 1rem;
}

.hero-name em {
  font-style: italic;
  font-weight: 300;
  color: var(--cyan);
}

.hero-role {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}

.hero-bio {
  max-width: 520px;
  color: rgba(245,240,232,0.75);
  font-size: 1.05rem;
  line-height: 1.75;
  margin-bottom: 2rem;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.stat { text-align: center; }

.stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: 2.25rem;
  font-weight: 600;
  color: var(--cyan);
  line-height: 1;
}

.stat-label {
  font-size: 0.75rem;
  color: var(--muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-top: 0.25rem;
  display: block;
}

.stat-div {
  width: 1px;
  height: 40px;
  background: var(--border);
}

.hero-cta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn-primary {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  background: var(--cyan);
  color: var(--navy);
  font-weight: 700;
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
  letter-spacing: 0.02em;
}

.btn-primary:hover {
  background: #33DDFF;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px var(--cyan-glow);
}

.btn-ghost {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border: 1px solid rgba(255,255,255,0.2);
  color: var(--cream);
  font-weight: 500;
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

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

/* Hero photo */
.hero-visual {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.photo-frame {
  position: relative;
  width: 300px;
  height: 300px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.photo-ring {
  position: absolute;
  border-radius: 50%;
  border: 1px solid rgba(0,212,255,0.2);
  animation: spin 18s linear infinite;
}

.photo-ring-1 {
  width: 340px;
  height: 340px;
  border-style: dashed;
  border-color: rgba(0,212,255,0.15);
  animation-duration: 22s;
}

.photo-ring-2 {
  width: 318px;
  height: 318px;
  border-color: rgba(0,212,255,0.3);
  animation-direction: reverse;
  animation-duration: 14s;
}

@keyframes spin { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }

.hero-photo {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 3px solid var(--cyan);
  box-shadow:
    0 0 0 6px rgba(0,212,255,0.08),
    0 0 40px rgba(0,212,255,0.2),
    0 20px 60px rgba(0,0,0,0.5);
  position: relative;
  z-index: 2;
  transition: box-shadow 0.4s ease;
}

.hero-photo:hover {
  box-shadow:
    0 0 0 8px rgba(0,212,255,0.12),
    0 0 60px rgba(0,212,255,0.35),
    0 20px 60px rgba(0,0,0,0.5);
}

/* ── SECTIONS ─────────────────────────── */
.section {
  padding: 6rem 0;
}

.section-alt {
  background: var(--navy-mid);
}

.section-header {
  margin-bottom: 3.5rem;
}

.section-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  display: block;
  margin-bottom: 0.5rem;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  color: var(--white);
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.section-sub {
  color: var(--muted);
  font-size: 1rem;
  margin-top: 0.75rem;
  max-width: 600px;
}

/* ── RESEARCH GRID ────────────────────── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.research-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(8px);
}

.research-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: transparent;
  transition: background var(--transition);
}

.research-card:hover {
  border-color: rgba(0,212,255,0.3);
  transform: translateY(-4px);
  box-shadow: 0 16px 40px rgba(0,0,0,0.3);
}

.research-card:hover::before {
  background: linear-gradient(90deg, var(--cyan), transparent);
}

.research-card.featured {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem 2rem;
  align-items: start;
  border-color: rgba(0,212,255,0.25);
}

.research-card.featured::before {
  background: linear-gradient(90deg, var(--cyan), rgba(0,212,255,0.3));
}

.research-card.featured h3 {
  grid-column: 1 / -1;
}

.card-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--cyan);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.research-card h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}

.research-card p {
  color: rgba(245,240,232,0.7);
  font-size: 0.9rem;
  line-height: 1.7;
}

.research-card p strong {
  color: var(--cyan);
  font-weight: 600;
}

.card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 1.25rem;
}

.chip {
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: var(--cyan);
  background: var(--cyan-dim);
  border: 1px solid rgba(0,212,255,0.2);
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
}

.card-link {
  display: inline-block;
  margin-top: 1.25rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--cyan);
  transition: gap var(--transition);
}

.card-link:hover { opacity: 0.75; }

/* ── TIMELINE ─────────────────────────── */
.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 12px;
  bottom: 12px;
  width: 1px;
  background: linear-gradient(to bottom, var(--cyan), transparent);
}

.timeline-item {
  position: relative;
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}

.timeline-dot {
  position: absolute;
  left: -2.375rem;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 10px var(--cyan-glow);
}

.timeline-meta {
  display: flex;
  flex-direction: column;
  padding-top: 2px;
}

.timeline-period {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
}

.timeline-loc {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 0.25rem;
}

.timeline-role {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--white);
  line-height: 1.2;
}

.timeline-company {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--cyan);
  margin: 0.3rem 0 1rem;
}

.timeline-list li {
  color: rgba(245,240,232,0.7);
  font-size: 0.9rem;
  padding-left: 1rem;
  position: relative;
  margin-bottom: 0.5rem;
}

.timeline-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--cyan);
  opacity: 0.5;
}

/* ── SKILLS ───────────────────────────── */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem 4rem;
}

.skill-group.full-width {
  grid-column: 1 / -1;
}

.skill-group-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}

.skill-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.skill-name {
  font-size: 0.875rem;
  color: var(--cream);
  min-width: 180px;
  flex-shrink: 0;
}

.skill-bar {
  flex: 1;
  height: 4px;
  background: rgba(255,255,255,0.08);
  border-radius: 999px;
  overflow: hidden;
}

.skill-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), rgba(0,212,255,0.5));
  border-radius: 999px;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 1s cubic-bezier(0.4,0,0.2,1);
}

.skill-fill.animated { transform: scaleX(1); }

.chips-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.chip-lg {
  font-size: 0.8rem;
  font-family: var(--font-mono);
  color: var(--cream);
  background: var(--navy-light);
  border: 1px solid var(--border);
  padding: 0.4rem 1rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.chip-lg:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

/* ── EDUCATION ────────────────────────── */
.edu-grid {
  display: grid;
  gap: 1rem;
}

.edu-card {
  display: flex;
  align-items: flex-start;
  gap: 1.5rem;
  padding: 1.5rem 1.75rem;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all var(--transition);
  backdrop-filter: blur(8px);
}

.edu-card:hover {
  border-color: rgba(0,212,255,0.3);
  transform: translateX(4px);
}

.edu-icon { font-size: 1.75rem; }

.edu-card h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 0.3rem;
}

.edu-inst {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--cyan);
}

.edu-period {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 0.2rem;
  font-family: var(--font-mono);
}

/* ── CONTACT ──────────────────────────── */
.contact-section {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-mid) 100%);
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}

.contact-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.5rem;
  padding: 2rem 1.5rem;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all var(--transition);
  backdrop-filter: blur(8px);
  cursor: pointer;
}

.contact-card:hover {
  border-color: rgba(0,212,255,0.4);
  transform: translateY(-4px);
  box-shadow: 0 12px 30px rgba(0,0,0,0.3);
}

.contact-icon { font-size: 1.75rem; }

.contact-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--cyan);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.contact-value {
  font-size: 0.85rem;
  color: var(--cream);
  word-break: break-all;
}

/* ── FOOTER ───────────────────────────── */
.footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  text-align: center;
}

.footer p {
  font-size: 0.8rem;
  color: var(--muted);
  font-family: var(--font-mono);
}

/* ── RESPONSIVE ───────────────────────── */
@media (max-width: 900px) {
  .hero {
    flex-direction: column;
    text-align: center;
    padding-top: 6rem;
  }

  .hero-bio { margin: 0 auto 2rem; }
  .hero-stats { justify-content: center; }
  .hero-cta { justify-content: center; }
  .hero-visual { order: -1; }
  .photo-frame { width: 200px; height: 200px; }
  .hero-photo { width: 185px; height: 185px; }
  .photo-ring-1 { width: 230px; height: 230px; }
  .photo-ring-2 { width: 212px; height: 212px; }

  .research-card.featured {
    grid-template-columns: 1fr;
    grid-column: auto;
  }

  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }

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

  .skill-name { min-width: 140px; }
}

@media (max-width: 640px) {
  .nav-links { display: none; }
  .nav-toggle { display: block; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 60px;
    left: 0; right: 0;
    background: var(--navy);
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border);
    gap: 1.25rem;
    z-index: 99;
  }

  .section { padding: 4rem 0; }
  .hero-name { font-size: 2.6rem; }
  .timeline { padding-left: 1rem; }
  .timeline::before { left: -1rem; }
  .timeline-dot { left: -1.375rem; }
  .edu-card { flex-direction: column; gap: 0.75rem; }
}

/* ── SCROLL ANIMATIONS ────────────────── */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

/* ── SCROLLBAR ────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--navy); }
::-webkit-scrollbar-thumb { background: var(--navy-light); border-radius: 999px; }
::-webkit-scrollbar-thumb:hover { background: var(--cyan); }