:root {
  --bg: #fafafa;
  --bg-alt: #ffffff;
  --surface: #ffffff;
  --text: #18181b;
  --text-muted: #71717a;
  --border: #e4e4e7;
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --accent: #a855f7;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 8px 24px rgba(0, 0, 0, 0.06);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    "PingFang SC", "Microsoft YaHei", sans-serif;
  --max-w: 1080px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 72px;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Header ---------- */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 250, 250, 0.82);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.site-header.scrolled {
  border-bottom-color: var(--border);
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.05);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.5px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--text-muted);
  transition: color 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--text);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Hero ---------- */

.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: radial-gradient(60% 50% at 50% 0%, rgba(99, 102, 241, 0.1), transparent),
    radial-gradient(40% 40% at 80% 20%, rgba(168, 85, 247, 0.08), transparent);
}

.hero-inner {
  text-align: center;
  padding: 120px 24px 80px;
}

.avatar {
  width: 112px;
  height: 112px;
  margin: 0 auto 24px;
  border-radius: 50%;
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.15), rgba(168, 85, 247, 0.15));
  box-shadow: var(--shadow);
  animation: float 5s ease-in-out infinite;
}

.avatar svg {
  width: 100%;
  height: 100%;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.hero-eyebrow {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.hero-title {
  font-size: clamp(2.4rem, 6vw, 4rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.hero-role {
  font-size: 1.15rem;
  color: var(--primary-dark);
  font-weight: 600;
  margin-bottom: 16px;
}

.hero-desc {
  max-width: 560px;
  margin: 0 auto 28px;
  color: var(--text-muted);
  font-size: 1.05rem;
}

.hero-social {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-bottom: 32px;
}

.hero-social a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.hero-social a:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow);
}

.hero-social svg {
  width: 20px;
  height: 20px;
  fill: var(--text);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.35);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-ghost:hover {
  border-color: var(--primary);
  color: var(--primary-dark);
}

.btn-sm {
  padding: 8px 20px;
  font-size: 0.85rem;
}

/* ---------- Sections ---------- */

.section {
  padding: 96px 24px;
}

.section-alt {
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.section-title {
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  font-weight: 800;
  letter-spacing: -0.01em;
  margin-bottom: 12px;
}

.section-lead {
  color: var(--text-muted);
  max-width: 640px;
  margin-bottom: 48px;
}

.section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 12px;
}

/* ---------- About ---------- */

.about-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: start;
}

.about-text p {
  margin-bottom: 16px;
  color: var(--text);
}

.skills {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.tag {
  padding: 6px 14px;
  border-radius: 999px;
  background: #fff;
  border: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
  transition: border-color 0.2s ease, color 0.2s ease;
}

.tag:hover {
  border-color: var(--primary);
  color: var(--primary-dark);
}

/* ---------- Timeline ---------- */

.timeline {
  position: relative;
  padding-left: 28px;
  max-width: 720px;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 4px;
  bottom: 4px;
  width: 2px;
  background: linear-gradient(to bottom, var(--primary), var(--accent));
  border-radius: 2px;
}

.timeline-item {
  position: relative;
  padding-bottom: 40px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-marker {
  position: absolute;
  left: -28px;
  top: 6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--primary);
  box-sizing: border-box;
}

.timeline-content h3 {
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.timeline-date {
  display: inline-block;
  font-size: 0.82rem;
  color: var(--primary-dark);
  font-weight: 600;
  margin-bottom: 8px;
}

.timeline-content p {
  color: var(--text-muted);
}

/* ---------- Blog ---------- */

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

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: rgba(99, 102, 241, 0.4);
}

.card-category {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--primary-dark);
  background: rgba(99, 102, 241, 0.08);
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 14px;
}

.card h3 {
  font-size: 1.1rem;
  line-height: 1.5;
  margin-bottom: 10px;
}

.card h3 a:hover {
  color: var(--primary-dark);
}

.card p {
  color: var(--text-muted);
  font-size: 0.93rem;
  margin-bottom: 16px;
}

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

/* ---------- Contact ---------- */

.contact-inner {
  text-align: center;
}

.contact-inner .section-lead {
  margin-left: auto;
  margin-right: auto;
}

.contact-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

/* ---------- Footer ---------- */

.site-footer {
  padding: 32px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.accent {
  color: var(--primary);
  font-weight: 700;
}

/* ---------- Reveal animation ---------- */

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ---------- Responsive ---------- */

@media (max-width: 860px) {
  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

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

@media (max-width: 640px) {
  .section {
    padding: 72px 20px;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
  }

  .nav-links.open {
    max-height: 320px;
  }

  .nav-links a {
    display: block;
    padding: 16px 24px;
    border-top: 1px solid var(--border);
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .avatar {
    animation: none;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}