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

:root {
  --bg:          #f8fafc;
  --bg-card:     #ffffff;
  --bg-alt:      #f1f5f9;
  --border:      #e2e8f0;
  --text:        #0f172a;
  --text-muted:  #475569;
  --text-faint:  #94a3b8;
  --accent:      #0284c7;
  --accent-dim:  rgba(2,132,199,.08);
  --radius:      12px;
  --radius-sm:   7px;
  --max-w:       1100px;
  --nav-h:       64px;
  --transition:  0.2s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

/* ===========================
   NAVBAR
   =========================== */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-h);
  transition: background var(--transition), border-color var(--transition), backdrop-filter var(--transition);
  border-bottom: 1px solid transparent;
}
.navbar.scrolled {
  background: rgba(248,250,252,.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom-color: var(--border);
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  height: 100%;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-brand {
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  color: var(--text);
  transition: color var(--transition);
}
.nav-brand:hover { color: var(--accent); }
.nav-links {
  list-style: none;
  display: flex;
  gap: 2rem;
}
.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.02em;
  transition: color var(--transition);
}
.nav-links a:hover { color: var(--text); }

/* ===========================
   HERO
   =========================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: calc(var(--nav-h) + 3rem) 2rem 5rem;
  background:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(2,132,199,.07) 0%, transparent 60%);
}
.hero-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  width: 100%;
  display: flex;
  align-items: center;
  gap: 5rem;
}
.hero-text { flex: 1; }
.hero-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid rgba(2,132,199,.2);
  padding: 0.3rem 0.9rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
}
.hero-name {
  font-size: clamp(3rem, 6vw, 5.5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: 0.75rem;
  color: var(--text);
}
.hero-tagline {
  font-size: clamp(1.25rem, 2.5vw, 1.75rem);
  font-weight: 400;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}
.accent { color: var(--accent); }
.hero-bio {
  font-size: 1rem;
  color: var(--text-muted);
  line-height: 1.75;
  max-width: 520px;
  margin-bottom: 2.5rem;
}
.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* ===========================
   BUTTONS
   =========================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  transition: all var(--transition);
  cursor: pointer;
}
.btn-primary {
  background: var(--accent);
  color: #ffffff;
}
.btn-primary:hover {
  background: #0369a1;
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(2,132,199,.25);
}
.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}
.btn-ghost:hover {
  background: var(--bg-alt);
  color: var(--text);
  border-color: #cbd5e1;
}

/* ===========================
   HERO PHOTO
   =========================== */
.hero-photo {
  flex-shrink: 0;
}
.photo-ring {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  padding: 3px;
  background: linear-gradient(135deg, var(--accent), #818cf8, #34d399);
  box-shadow: 0 0 50px rgba(2,132,199,.18);
}
.photo-ring img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--bg);
}

/* ===========================
   SECTIONS
   =========================== */
.section {
  padding: 6rem 2rem;
}
.section-alt {
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.section-inner {
  max-width: var(--max-w);
  margin: 0 auto;
}
.section-title {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 3rem;
  position: relative;
  color: var(--text);
}
.section-title::after {
  content: '';
  display: block;
  width: 40px;
  height: 3px;
  background: var(--accent);
  border-radius: 2px;
  margin-top: 0.6rem;
}

/* ===========================
   PROJECTS GRID
   =========================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 1.5rem;
}
.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.project-card:hover {
  transform: translateY(-4px);
  border-color: #cbd5e1;
  box-shadow: 0 16px 40px rgba(15,23,42,.08);
}
.project-img-wrap {
  width: 100%;
  aspect-ratio: 16/9;
  overflow: hidden;
  background: #e2e8f0;
}
.project-img-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}
.project-card:hover .project-img-wrap img {
  transform: scale(1.04);
}
.project-info {
  padding: 1.5rem;
}
.project-title {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
  color: var(--text);
}
.project-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1rem;
}
.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

/* ===========================
   SKILL TAGS / TAGS
   =========================== */
.tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  padding: 0.25rem 0.6rem;
  border-radius: 4px;
  letter-spacing: 0.02em;
}

/* ===========================
   SKILLS GRID
   =========================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 2rem;
}
.skill-group-title {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 0.75rem;
}
.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* ===========================
   CONTACT
   =========================== */
.contact-inner {
  text-align: center;
  max-width: 600px;
}
.contact-inner .section-title::after {
  margin: 0.6rem auto 0;
}
.contact-sub {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 2rem;
}

/* ===========================
   FOOTER
   =========================== */
.footer {
  border-top: 1px solid var(--border);
  padding: 2rem;
  background: var(--bg-card);
}
.footer-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}
.footer-copy {
  font-size: 0.8rem;
  color: var(--text-faint);
}
.footer-links {
  display: flex;
  gap: 1.5rem;
}
.footer-links a {
  font-size: 0.8rem;
  color: var(--text-faint);
  transition: color var(--transition);
}
.footer-links a:hover { color: var(--text-muted); }

/* ===========================
   PAGE (About / Resume)
   =========================== */
.page-container {
  padding: calc(var(--nav-h) + 3rem) 2rem 5rem;
}
.page-inner {
  max-width: 800px;
  margin: 0 auto;
}
.page-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 2.5rem;
  color: var(--text);
}
.page-content { color: var(--text-muted); line-height: 1.8; }
.page-content h2 { color: var(--text); font-size: 1.4rem; font-weight: 600; letter-spacing: -0.02em; margin: 2.5rem 0 1rem; }
.page-content h3 { color: var(--text); font-size: 1.1rem; font-weight: 600; margin: 1.5rem 0 0.5rem; }
.page-content p { margin-bottom: 1rem; }
.page-content ul { padding-left: 1.5rem; margin-bottom: 1rem; }
.page-content li { margin-bottom: 0.35rem; }
.page-content a { color: var(--accent); border-bottom: 1px solid rgba(2,132,199,.25); transition: border-color var(--transition); }
.page-content a:hover { border-bottom-color: var(--accent); }
.page-content img { border-radius: var(--radius-sm); max-width: 100%; margin: 1.5rem auto; }
.page-content hr { border: none; border-top: 1px solid var(--border); margin: 2.5rem 0; }
.page-content strong { color: var(--text); font-weight: 600; }

/* ===========================
   POST (Project detail)
   =========================== */
.post-container {
  padding: calc(var(--nav-h) + 2rem) 2rem 5rem;
}
.post-inner {
  max-width: 860px;
  margin: 0 auto;
}
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  transition: color var(--transition);
}
.back-link:hover { color: var(--text); }
.post-hero-img {
  width: 100%;
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 2rem;
  border: 1px solid var(--border);
}
.post-hero-img img { width: 100%; }
.post-title {
  font-size: clamp(1.75rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 2.5rem;
  color: var(--text);
}
.post-content { color: var(--text-muted); line-height: 1.85; }
.post-content h2 { color: var(--text); font-size: 1.5rem; font-weight: 700; letter-spacing: -0.02em; margin: 3rem 0 1rem; border-top: 1px solid var(--border); padding-top: 2rem; }
.post-content h3 { color: var(--text); font-size: 1.15rem; font-weight: 600; margin: 1.75rem 0 0.5rem; }
.post-content p { margin-bottom: 1.25rem; }
.post-content ul, .post-content ol { padding-left: 1.5rem; margin-bottom: 1.25rem; }
.post-content li { margin-bottom: 0.4rem; }
.post-content a { color: var(--accent); }
.post-content a:hover { text-decoration: underline; }
.post-content img { border-radius: var(--radius-sm); margin: 1.5rem auto; border: 1px solid var(--border); }
.post-content video { border-radius: var(--radius-sm); border: 1px solid var(--border); }
.post-content strong { color: var(--text); font-weight: 600; }
.post-content code { background: var(--bg-alt); border: 1px solid var(--border); padding: 0.15em 0.4em; border-radius: 4px; font-size: 0.85em; }

/* ===========================
   RESPONSIVE
   =========================== */
@media (max-width: 768px) {
  .hero-inner {
    flex-direction: column-reverse;
    gap: 2.5rem;
    text-align: center;
  }
  .hero-bio { max-width: 100%; }
  .hero-cta { justify-content: center; }
  .photo-ring { width: 180px; height: 180px; }
  .projects-grid { grid-template-columns: 1fr; }
  .skills-grid { grid-template-columns: 1fr 1fr; }
  .nav-inner { padding: 0 1.25rem; }
}

@media (max-width: 480px) {
  .skills-grid { grid-template-columns: 1fr; }
  .section { padding: 4rem 1.25rem; }
}

/* ===========================
   GRADIENT BACKGROUND
   =========================== */
.gradient-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
}
.gradient-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(90px);
  will-change: transform, opacity;
  transform-origin: center;
  opacity: 0;
}
main   { position: relative; z-index: 1; }
.footer { position: relative; z-index: 1; }

/* ===========================
   SCROLL FADE-IN (Apple-style)
   =========================== */
.fade-in {
  opacity: 0;
  transform: translateY(22px);
  transition:
    opacity   0.75s cubic-bezier(0.16, 1, 0.3, 1),
    transform 0.75s cubic-bezier(0.16, 1, 0.3, 1);
  transition-delay: calc(var(--stagger, 0) * 0.07s);
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}