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

:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-border: #e2e8f0;
  --color-tag-html: #e34c26;
  --color-tag-css: #264de4;
  --color-tag-js: #f7df1e;
  --color-tag-vue: #42b883;
  --color-tag-react: #61dafb;
  --color-tag-tool: #8b5cf6;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
  --radius: 12px;
  --max-width: 1100px;
  --transition: 0.3s ease;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 70px;
}

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

a {
  text-decoration: none;
  color: var(--color-primary);
}

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

/* ===== Navbar ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: var(--transition);
}

.navbar.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 8px;
}

.nav-link {
  display: inline-block;
  padding: 8px 16px;
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  border-radius: 8px;
  transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
  background: rgba(37, 99, 235, 0.06);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
  min-height: 80vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 80px;
  background: linear-gradient(160deg, #eff6ff 0%, #dbeafe 40%, #c7d2fe 100%);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto 36px;
  line-height: 1.8;
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  border: none;
}

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

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.3);
}

/* ===== Sections ===== */
.section {
  padding: 80px 0;
}

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

.section-title {
  font-size: 1.8rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.section-desc {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: 48px;
  font-size: 1.05rem;
}

/* ===== Article Grid ===== */
.article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}

.article-card {
  display: block;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: var(--transition);
  position: relative;
  cursor: pointer;
  color: inherit;
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.article-tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 6px;
  margin-bottom: 14px;
  background: rgba(37, 99, 235, 0.1);
  color: var(--color-primary);
}

.tag-html { background: rgba(227, 76, 38, 0.1); color: var(--color-tag-html); }
.tag-css  { background: rgba(38, 77, 228, 0.1); color: var(--color-tag-css); }
.tag-js   { background: rgba(250, 220, 30, 0.15); color: #a16207; }
.tag-vue  { background: rgba(66, 184, 131, 0.12); color: var(--color-tag-vue); }
.tag-react { background: rgba(97, 218, 251, 0.15); color: #0e7490; }
.tag-tool { background: rgba(139, 92, 246, 0.1); color: var(--color-tag-tool); }

.article-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 10px;
  line-height: 1.5;
}

.article-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
}

.article-meta {
  display: flex;
  gap: 16px;
  font-size: 0.8rem;
  color: #94a3b8;
}

/* ===== Author Brief ===== */
.author-card {
  display: flex;
  align-items: center;
  gap: 36px;
  background: linear-gradient(135deg, #eff6ff, #f0f0ff);
  border-radius: var(--radius);
  padding: 40px;
}

.author-avatar {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  font-size: 2.5rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.author-info h3 {
  font-size: 1.3rem;
  margin-bottom: 8px;
}

.author-info p {
  color: var(--color-text-secondary);
  margin-bottom: 20px;
}

.author-stats {
  display: flex;
  gap: 32px;
}

.stat {
  text-align: center;
}

.stat strong {
  display: block;
  font-size: 1.4rem;
  color: var(--color-primary);
}

.stat span {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

/* ===== Project Grid ===== */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: var(--transition);
  cursor: pointer;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.project-icon {
  font-size: 2.2rem;
  margin-bottom: 16px;
}

.project-title {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.project-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin-bottom: 18px;
  line-height: 1.7;
}

.project-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.project-tags span {
  padding: 4px 12px;
  font-size: 0.78rem;
  border-radius: 6px;
  background: var(--color-bg-alt);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

/* ===== About ===== */
.about-content {
  display: flex;
  gap: 48px;
  align-items: flex-start;
  max-width: 800px;
  margin: 0 auto;
}

.about-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), #7c3aed);
  color: #fff;
  font-size: 3rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.about-text h3 {
  font-size: 1.3rem;
  margin-bottom: 12px;
}

.about-text p {
  color: var(--color-text-secondary);
  margin-bottom: 12px;
  line-height: 1.8;
}

.contact-links {
  display: flex;
  gap: 16px;
  margin: 24px 0;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  font-size: 0.9rem;
  color: var(--color-text);
  transition: var(--transition);
}

.contact-item:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.contact-icon {
  font-weight: 700;
  font-size: 0.85rem;
}

.friend-links h4 {
  font-size: 1rem;
  margin-bottom: 12px;
}

.link-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.link-list a {
  padding: 6px 14px;
  background: var(--color-bg-alt);
  border-radius: 6px;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  transition: var(--transition);
}

.link-list a:hover {
  color: var(--color-primary);
  background: rgba(37, 99, 235, 0.06);
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 32px 0;
  color: #94a3b8;
  font-size: 0.85rem;
  border-top: 1px solid var(--color-border);
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 16px;
    border-bottom: 1px solid var(--color-border);
    transform: translateY(-120%);
    transition: var(--transition);
  }

  .nav-menu.open {
    transform: translateY(0);
  }

  .hero {
    min-height: 60vh;
    padding: 100px 24px 60px;
  }

  .author-card {
    flex-direction: column;
    text-align: center;
    padding: 32px 24px;
  }

  .author-stats {
    justify-content: center;
  }

  .about-content {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .contact-links {
    justify-content: center;
  }

  .link-list {
    justify-content: center;
  }

  .section {
    padding: 60px 0;
  }
}

@media (max-width: 480px) {
  .article-grid {
    grid-template-columns: 1fr;
  }

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

  .contact-links {
    flex-direction: column;
    align-items: center;
  }
}