/* ===========================
   CSS 变量 & 全局重置
   =========================== */
:root {
  --bg: #0d0d0d;
  --surface: #141414;
  --surface-2: #1c1c1c;
  --border: rgba(255, 255, 255, 0.08);
  --text: #e8e8e8;
  --text-muted: #888;
  --text-dim: #555;
  --accent: #c8ff57;
  --header-h: 64px;
  --max-w: 860px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

em {
  font-style: normal;
  color: var(--accent);
}

strong {
  font-weight: 600;
  color: var(--text);
}

/* ===========================
   容器
   =========================== */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 32px;
}

/* ===========================
   顶部导航
   =========================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(13, 13, 13, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition);
}

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

.header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 32px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
  transition: opacity var(--transition);
}

.site-logo:hover {
  opacity: 0.7;
}

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

.main-nav {
  display: flex;
  align-items: center;
  gap: 32px;
}

.main-nav ul {
  list-style: none;
  display: flex;
  gap: 28px;
}

.nav-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color var(--transition);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--accent);
  transition: width var(--transition);
}

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

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* 顶部右侧区域 */
.header-right {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* 语言切换按钮 */
.lang-toggle {
  display: flex;
  align-items: center;
  gap: 4px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 5px 10px;
  cursor: pointer;
  transition: all var(--transition);
}

.lang-toggle:hover {
  border-color: rgba(255, 255, 255, 0.2);
}

.lang-option {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-dim);
  letter-spacing: 0.05em;
  transition: color var(--transition);
  line-height: 1;
}

.lang-option.active {
  color: var(--accent);
}

.lang-divider {
  font-size: 0.7rem;
  color: var(--text-dim);
  line-height: 1;
}

.nav-resume {
  font-size: 0.8rem;
  font-weight: 600;
  padding: 7px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  transition: all var(--transition);
  letter-spacing: 0.03em;
}

.nav-resume:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(200, 255, 87, 0.05);
}

/* 语言切换过渡动画 */
body.lang-switching main,
body.lang-switching footer {
  opacity: 0;
  transition: opacity 0.2s ease;
}

body main,
body footer {
  transition: opacity 0.25s ease;
}

/* 汉堡菜单 */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--text);
  transition: all var(--transition);
}

/* ===========================
   通用 Section 样式
   =========================== */
.section {
  padding: 100px 0;
}

.section:first-of-type {
  padding-top: calc(var(--header-h) + 80px);
}

.section-label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 24px;
}

.section-title {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--text);
  margin-bottom: 48px;
}

/* ===========================
   关于 Section
   =========================== */
.about-title {
  font-size: clamp(3rem, 8vw, 5.5rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: 32px;
  color: var(--text);
}

.gradient-text {
  color: var(--accent);
}

.about-intro {
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 600px;
  margin-bottom: 32px;
  line-height: 1.8;
}

.about-body {
  font-size: 1rem;
  color: var(--text-muted);
  max-width: 620px;
  margin-bottom: 64px;
  line-height: 1.9;
}

.about-sub-sections {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  padding-top: 48px;
  border-top: 1px solid var(--border);
}

.about-sub-sections--single {
  grid-template-columns: 1fr;
  max-width: 560px;
}

.sub-section h3 {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-bottom: 12px;
}

.sub-section p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.8;
}

/* ===========================
   技能 Section
   =========================== */
.section--skills {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.skill-card {
  background: var(--surface);
  padding: 32px 28px;
  transition: background var(--transition);
}

.skill-card:hover {
  background: var(--surface-2);
}

.skill-icon {
  font-size: 1.5rem;
  margin-bottom: 16px;
  color: var(--accent);
  line-height: 1;
}

.skill-card h4 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text);
  letter-spacing: -0.01em;
}

.skill-card p {
  font-size: 0.83rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ===========================
   作品 Section
   =========================== */
.projects-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.project-card {
  padding: 40px 0;
  border-bottom: 1px solid var(--border);
  transition: all var(--transition);
  cursor: default;
}

.project-card:first-child {
  border-top: 1px solid var(--border);
}

.project-card:hover {
  padding-left: 16px;
}

.project-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
}

.project-tag {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  background: rgba(200, 255, 87, 0.08);
  padding: 3px 9px;
  border-radius: 4px;
  border: 1px solid rgba(200, 255, 87, 0.2);
}

.project-year {
  font-size: 0.78rem;
  color: var(--text-dim);
  font-weight: 500;
}

.project-title {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
  line-height: 1.3;
}

.project-title a {
  color: var(--text);
  transition: color var(--transition);
}

.project-title a:hover {
  color: var(--accent);
}

.project-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  max-width: 560px;
  line-height: 1.8;
  margin-bottom: 20px;
}

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

.project-tags span {
  font-size: 0.75rem;
  color: var(--text-dim);
  border: 1px solid var(--border);
  padding: 3px 10px;
  border-radius: 20px;
  transition: all var(--transition);
}

.project-card:hover .project-tags span {
  border-color: rgba(255, 255, 255, 0.15);
  color: var(--text-muted);
}

.projects-more {
  margin-top: 40px;
}

.more-link {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.02em;
  transition: color var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.more-link:hover {
  color: var(--accent);
}

/* ===========================
   联系 Section
   =========================== */
.section--contact {
  background: var(--surface);
  border-top: 1px solid var(--border);
}

.contact-intro {
  font-size: 1rem;
  color: var(--text-muted);
  line-height: 1.9;
  max-width: 500px;
  margin-bottom: 48px;
}

.contact-email {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

#email-text {
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  letter-spacing: 0.01em;
}

.copy-btn {
  font-size: 0.78rem;
  font-weight: 600;
  padding: 7px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: none;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
  letter-spacing: 0.05em;
}

.copy-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(200, 255, 87, 0.05);
}

.copy-btn.copied {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(200, 255, 87, 0.1);
}

.social-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.social-link {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color var(--transition);
  position: relative;
}

.social-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--accent);
  transition: width var(--transition);
}

.social-link:hover {
  color: var(--text);
}

.social-link:hover::after {
  width: 100%;
}

/* ===========================
   页脚
   =========================== */
.site-footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
}

.site-footer p {
  font-size: 0.78rem;
  color: var(--text-dim);
  text-align: center;
}

/* ===========================
   滚动进场动画
   =========================== */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===========================
   响应式
   =========================== */
@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }

  .section {
    padding: 72px 0;
  }

  .section:first-of-type {
    padding-top: calc(var(--header-h) + 56px);
  }

  /* 移动端导航 */
  .header-right {
    gap: 12px;
  }

  .menu-toggle {
    display: flex;
  }

  .main-nav {
    display: none;
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 24px 20px;
  }

  .main-nav.open {
    display: flex;
  }

  .main-nav ul {
    flex-direction: column;
    gap: 0;
    width: 100%;
  }

  .main-nav ul li {
    border-bottom: 1px solid var(--border);
  }

  .nav-link {
    display: block;
    padding: 14px 0;
    font-size: 1rem;
  }

  .nav-resume {
    margin-top: 20px;
  }

  /* 关于 */
  .about-sub-sections {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  /* 技能 */
  .skills-grid {
    grid-template-columns: 1fr 1fr;
  }

  /* 作品 */
  .project-card:hover {
    padding-left: 0;
  }
}

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

  .about-title {
    font-size: 3rem;
  }
}

/* ===========================
   自定义滚动条
   =========================== */
::-webkit-scrollbar {
  width: 4px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: var(--text-dim);
  border-radius: 2px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* ===========================
   文字选中
   =========================== */
::selection {
  background: rgba(200, 255, 87, 0.25);
  color: var(--text);
}