:root {
  --bg: #ffffff;
  --bg-alt: #f6f7fb;
  --text: #1a1d26;
  --text-muted: #5b6270;
  --border: #e6e8ee;
  --accent: #4f6ef7;
  --accent-soft: rgba(79, 110, 247, 0.1);
  --shadow: 0 10px 30px rgba(26, 29, 38, 0.06);
  --radius: 16px;
  --max-width: 1080px;
  --transition: 0.25s ease;
}

[data-theme="dark"] {
  --bg: #0f1117;
  --bg-alt: #161a23;
  --text: #eef0f6;
  --text-muted: #9aa1b1;
  --border: #262b38;
  --accent: #7d95ff;
  --accent-soft: rgba(125, 149, 255, 0.12);
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

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

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

/* ---------- Header ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition);
}

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

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

.brand {
  font-size: 22px;
  font-weight: 800;
  color: var(--text);
  text-decoration: none;
  letter-spacing: 0.5px;
}

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

.nav-links {
  display: flex;
  gap: 36px;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
  position: relative;
  transition: color var(--transition);
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition);
}

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

.nav-links a:hover::after {
  width: 100%;
}

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  padding: 6px;
  display: flex;
  align-items: center;
  transition: color var(--transition);
}

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

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

[data-theme="dark"] .icon-moon {
  display: none;
}

.icon-sun {
  display: none;
}

[data-theme="dark"] .icon-sun {
  display: block;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  margin: 4px 0;
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

/* ---------- Hero ---------- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  padding: 120px 24px 80px;
}

.hero-inner {
  animation: fade-up 0.8s ease both;
}

.hero-avatar {
  position: relative;
  width: 108px;
  height: 108px;
  margin: 0 auto 28px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.avatar-ring {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  animation: spin 6s linear infinite;
}

.avatar-letter {
  width: 88px;
  height: 88px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 42px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-greeting {
  font-size: 17px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.hero-name {
  font-size: clamp(42px, 8vw, 68px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 12px;
  background: linear-gradient(120deg, var(--text) 40%, var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-role {
  font-size: clamp(18px, 3vw, 22px);
  font-weight: 600;
  color: var(--text);
  margin-bottom: 16px;
}

.hero-desc {
  max-width: 560px;
  margin: 0 auto 36px;
  color: var(--text-muted);
  font-size: 16px;
}

.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
}

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

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 24px var(--accent-soft);
}

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

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

.scroll-hint {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-muted);
  animation: bounce 2s infinite;
}

.scroll-hint svg {
  width: 24px;
  height: 24px;
}

/* ---------- Sections ---------- */
.section {
  padding: 100px 0;
}

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

.section-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 4px 14px;
  border-radius: 999px;
  margin-bottom: 16px;
}

.section-title {
  font-size: clamp(26px, 4vw, 36px);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 48px;
  max-width: 640px;
}

/* ---------- About ---------- */
.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.about-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  transition: transform var(--transition);
}

.about-card:hover {
  transform: translateY(-4px);
}

.about-card h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 14px;
  color: var(--accent);
}

.about-card p {
  color: var(--text-muted);
  margin-bottom: 12px;
}

.about-card p:last-child {
  margin-bottom: 0;
}

.about-list {
  list-style: none;
  color: var(--text-muted);
}

.about-list li {
  padding: 8px 0 8px 26px;
  position: relative;
}

.about-list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 16px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
}

/* ---------- Skills ---------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
}

.skill-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  box-shadow: var(--shadow);
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease, border-color var(--transition);
}

.skill-card.visible {
  opacity: 1;
  transform: translateY(0);
}

.skill-card:hover {
  border-color: var(--accent);
}

.skill-icon {
  font-size: 30px;
  font-weight: 800;
  color: var(--accent);
  margin-bottom: 12px;
  display: inline-block;
}

.skill-name {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 4px;
}

.skill-level {
  font-size: 13px;
  color: var(--text-muted);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 40px 0;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  color: var(--text-muted);
  font-size: 14px;
}

.footer-contact a {
  color: var(--accent);
  text-decoration: none;
}

.footer-contact a:hover {
  text-decoration: underline;
}

/* ---------- Animations ---------- */
@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes fade-up {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .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 0.3s ease;
  }

  .nav-links.open {
    max-height: 240px;
  }

  .nav-links li {
    width: 100%;
  }

  .nav-links a {
    display: block;
    padding: 14px 24px;
  }

  .nav-toggle {
    display: block;
    order: 3;
  }

  .theme-toggle {
    order: 2;
  }

  .section {
    padding: 72px 0;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

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

  .hero-inner,
  .skill-card,
  .avatar-ring,
  .scroll-hint {
    animation: none;
    transition: none;
  }
}