:root {
  --bg: #0d1117;
  --bg-soft: #161b22;
  --border: #30363d;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #4d6bfe;
  --accent-2: #38bdf8;
  --radius: 12px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}

.container { max-width: 960px; margin: 0 auto; padding: 0 24px; }

/* Nav */
.nav {
  position: sticky; top: 0; z-index: 10;
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.logo { font-weight: 700; letter-spacing: 0.5px; }
.nav nav a { color: var(--muted); text-decoration: none; margin-left: 20px; font-size: 0.95rem; }
.nav nav a:hover { color: var(--text); }

/* Hero */
.hero { padding: 96px 0 64px; text-align: center; }
.hero h1 { font-size: 2.6rem; margin-bottom: 12px; }
.accent {
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lead { font-size: 1.25rem; color: var(--text); margin-bottom: 12px; }
.sub { color: var(--muted); max-width: 640px; margin: 0 auto 28px; }
.hero-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* Buttons */
.btn {
  display: inline-block; padding: 10px 20px; border-radius: 999px;
  border: 1px solid var(--border); color: var(--text); text-decoration: none;
  transition: all 0.2s;
}
.btn:hover { border-color: var(--accent); transform: translateY(-1px); }
.btn.primary { background: linear-gradient(120deg, var(--accent), var(--accent-2)); border: none; color: #fff; font-weight: 600; }
.btn.small { padding: 6px 14px; font-size: 0.9rem; }

/* Sections */
section { padding: 64px 0; }
h2 { font-size: 1.6rem; margin-bottom: 24px; }
.about p { color: var(--muted); margin-bottom: 12px; max-width: 720px; }
.about strong, .projects strong { color: var(--text); }

/* Cards */
.card {
  background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px;
}
.featured-card { border-color: var(--accent); box-shadow: 0 0 40px rgba(77, 107, 254, 0.15); }
.featured-main h3 { font-size: 1.5rem; margin-bottom: 6px; }
.tagline { color: var(--accent-2); font-weight: 600; margin-bottom: 12px; }
.feature-list { list-style: none; margin: 16px 0; }
.feature-list li { color: var(--muted); margin-bottom: 8px; }
code { background: rgba(255,255,255,0.08); padding: 2px 6px; border-radius: 4px; font-size: 0.9em; }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }
.card h3 { margin-bottom: 8px; font-size: 1.1rem; }
.card p { color: var(--muted); font-size: 0.95rem; margin-bottom: 12px; }
.chip {
  display: inline-block; font-size: 0.78rem; color: var(--accent-2);
  border: 1px solid var(--border); border-radius: 999px; padding: 2px 10px; margin-right: 6px;
}

/* Skills */
.skill-tags { display: flex; flex-wrap: wrap; gap: 10px; }
.skill-tags span {
  background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: 999px; padding: 8px 16px; color: var(--text); font-size: 0.9rem;
}

/* Contact */
.contact a { color: var(--accent-2); text-decoration: none; }
.contact a:hover { text-decoration: underline; }
.contact p { color: var(--muted); margin-bottom: 8px; }

/* Footer */
.footer { border-top: 1px solid var(--border); padding: 28px 0; text-align: center; color: var(--muted); font-size: 0.9rem; }

@media (max-width: 640px) {
  .hero { padding: 64px 0 40px; }
  .hero h1 { font-size: 2rem; }
}