@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@300;400;500;600;700&family=Noto+Sans:wght@300;400;500;600;700&display=swap');

/* ===== 基础重置 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  background: #fdfbf7;
  color: #1a1a1a;
}

body {
  font-family: 'Noto Sans', 'Be Vietnam Pro', system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-size: 1rem;
  line-height: 1.75;
  background: #fdfbf7;
  color: #1a1a1a;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

/* ===== 纸质噪点纹理 ===== */
.noise-overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
  background-repeat: repeat;
  background-size: 128px 128px;
}

/* ===== 公告条 ===== */
.site-announce {
  background: #1a1a1a;
  color: #fdfbf7;
  text-align: center;
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  padding: 6px 16px;
  position: relative;
  z-index: 100;
  font-family: 'Be Vietnam Pro', sans-serif;
}

/* ===== 站头 ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: #fdfbf7;
  border-bottom: 1px solid #1a1a1a;
  transition: none;
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-logo-text {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: 1.25rem;
  font-weight: 700;
  color: #1a1a1a;
  text-decoration: none;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.brand-logo-img {
  display: flex;
  align-items: center;
  text-decoration: none;
}

.logo-img {
  height: 36px;
  width: auto;
}

/* ===== 汉堡按钮 ===== */
.hamburger-btn {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  background: none;
  border: 1px solid #1a1a1a;
  cursor: pointer;
  padding: 10px 9px;
  transition: none;
  flex-shrink: 0;
}

.ham-line {
  display: block;
  width: 100%;
  height: 1.5px;
  background: #1a1a1a;
  transition: none;
}

.hamburger-btn:hover {
  background: #1a1a1a;
}

.hamburger-btn:hover .ham-line {
  background: #fdfbf7;
}

/* ===== 全屏遮罩菜单 ===== */
.fullscreen-menu {
  position: fixed;
  inset: 0;
  z-index: 500;
  background: #1a1a1a;
  color: #fdfbf7;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: none;
}

.fullscreen-menu.is-open {
  opacity: 1;
  pointer-events: auto;
}

.menu-close-btn {
  position: absolute;
  top: 20px;
  right: 24px;
  background: none;
  border: 1px solid #fdfbf7;
  color: #fdfbf7;
  font-size: 1.25rem;
  width: 44px;
  height: 44px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Be Vietnam Pro', sans-serif;
  transition: none;
}

.menu-close-btn:hover {
  background: #fdfbf7;
  color: #1a1a1a;
}

.fullscreen-nav ol {
  list-style: none;
  text-align: center;
  padding: 0;
}

.fullscreen-nav ol li {
  margin: 0;
  border-top: 1px solid rgba(253, 251, 247, 0.12);
}

.fullscreen-nav ol li:last-child {
  border-bottom: 1px solid rgba(253, 251, 247, 0.12);
}

.fullscreen-nav ol li a {
  display: block;
  padding: 18px 48px;
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: 1.125rem;
  font-weight: 500;
  color: #fdfbf7;
  text-decoration: none;
  letter-spacing: 0.04em;
  min-height: 56px;
  line-height: 1.4;
  transition: none;
}

.fullscreen-nav ol li a:hover {
  background: rgba(253, 251, 247, 0.08);
  color: #fdfbf7;
}

/* 交错动画 */
@media (prefers-reduced-motion: no-preference) {
  .fullscreen-menu.is-open .fullscreen-nav ol li {
    animation: stagger-in 0.25s both;
  }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(1) { animation-delay: 0.04s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(2) { animation-delay: 0.08s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(3) { animation-delay: 0.12s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(4) { animation-delay: 0.16s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(5) { animation-delay: 0.20s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(6) { animation-delay: 0.24s; }
  .fullscreen-menu.is-open .fullscreen-nav ol li:nth-child(7) { animation-delay: 0.28s; }

  @keyframes stagger-in {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
  }
}

/* ===== scroll-margin for sticky nav ===== */
section[id] {
  scroll-margin-top: 80px;
}

/* ===== main / wrap ===== */
main {
  position: relative;
  z-index: 1;
}

.wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Hero ===== */
.hero-section {
  min-height: 45vh;
  display: flex;
  align-items: center;
  border-bottom: 1px solid #1a1a1a;
  padding: 48px 0 40px;
}

.hero-article {
  width: 100%;
}

.hero-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 40px;
  flex-wrap: wrap;
  text-align: center;
}

.hero-text {
  max-width: 600px;
}

.hero-text h1 {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.01em;
  margin-bottom: 16px;
  color: #1a1a1a;
}

.hero-desc {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: #3a3a3a;
  max-width: 480px;
  margin: 0 auto;
}

.hero-icon svg {
  display: block;
}

/* ===== 正文区域（aside + content） ===== */
.content-section {
  padding: 56px 0 80px;
}

.content-with-aside {
  display: flex;
  gap: 48px;
  align-items: flex-start;
}

/* aside 在内容左侧 */
.content-aside {
  width: 200px;
  flex-shrink: 0;
  position: sticky;
  top: 88px;
  border: 1px solid #1a1a1a;
  padding: 20px 16px;
  background: #f5f5f5;
}

.aside-label {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: #1a1a1a;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid #1a1a1a;
}

.content-aside ul {
  list-style: none;
  padding: 0;
}

.content-aside ul li {
  border-bottom: 1px solid rgba(26, 26, 26, 0.1);
}

.content-aside ul li:last-child {
  border-bottom: none;
}

.content-aside ul li a {
  display: block;
  padding: 8px 0;
  font-size: 0.8125rem;
  color: #1a1a1a;
  text-decoration: none;
  line-height: 1.5;
  min-height: 36px;
  display: flex;
  align-items: center;
  transition: none;
}

.content-aside ul li a:hover {
  color: #555;
}

.content-main {
  flex: 1;
  min-width: 0;
}

/* ===== 正文内容样式 ===== */
.content-main h2 {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: clamp(1.25rem, 2.5vw, 1.75rem);
  font-weight: 700;
  line-height: 1.3;
  margin-top: 56px;
  margin-bottom: 8px;
  color: #1a1a1a;
  letter-spacing: -0.01em;
}

.content-main h2:first-child {
  margin-top: 0;
}

.content-main h2 + hr,
.content-main h3 + hr {
  border: none;
  border-top: 1px solid #1a1a1a;
  margin: 0 0 20px 0;
}

.content-main hr {
  border: none;
  border-top: 1px solid #d0d0d0;
  margin: 32px 0;
}

.content-main h3 {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: 1.125rem;
  font-weight: 600;
  margin-top: 32px;
  margin-bottom: 8px;
  color: #1a1a1a;
}

.content-main p {
  font-size: 1rem;
  line-height: 1.8;
  margin-bottom: 16px;
  color: #1a1a1a;
}

.content-main ul,
.content-main ol {
  padding-left: 20px;
  margin-bottom: 16px;
}

.content-main li {
  line-height: 1.75;
  margin-bottom: 6px;
}

.content-main a {
  color: #1a1a1a;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.content-main a:hover {
  text-decoration: none;
}

.content-main strong {
  font-weight: 600;
}

.content-main blockquote {
  border-left: 3px solid #1a1a1a;
  margin: 24px 0;
  padding: 12px 20px;
  background: #f5f5f5;
  font-style: normal;
}

.content-main table {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  font-size: 0.9375rem;
}

.content-main th,
.content-main td {
  border: 1px solid #1a1a1a;
  padding: 10px 14px;
  text-align: left;
}

.content-main th {
  background: #1a1a1a;
  color: #fdfbf7;
  font-weight: 600;
}

.content-main td {
  background: #fdfbf7;
}

.content-main tr:nth-child(even) td {
  background: #f5f5f5;
}

/* 卡片（正文中的卡片化内容） */
.content-main .card {
  background: #f5f5f5;
  border: 1px solid #d0d0d0;
  border-radius: 28px;
  padding: 24px 28px;
  margin: 20px 0;
  box-shadow: 0 2px 8px rgba(26,26,26,0.06);
}

/* section 分隔 */
.content-main section {
  padding-top: 16px;
}

/* ===== 视差滚动（仅桌面，reduced-motion 关闭） ===== */
@media (prefers-reduced-motion: no-preference) and (min-width: 768px) {
  .hero-section {
    will-change: transform;
  }
}

/* ===== 页脚 ===== */
.site-footer {
  background: #1a1a1a;
  color: #fdfbf7;
  text-align: center;
  padding: 48px 24px 32px;
  border-top: 1px solid #1a1a1a;
}

.site-footer p.footer-cta {
  font-family: 'Be Vietnam Pro', sans-serif;
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  letter-spacing: 0.02em;
  color: #fdfbf7;
}

.site-footer small {
  display: block;
  font-size: 0.8125rem;
  line-height: 1.6;
  color: rgba(253, 251, 247, 0.6);
  max-width: 600px;
  margin: 0 auto;
}

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .content-with-aside {
    flex-direction: column;
    gap: 32px;
  }

  .content-aside {
    width: 100%;
    position: static;
  }

  .content-aside ul {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
  }

  .content-aside ul li {
    border-bottom: none;
  }

  .content-aside ul li a {
    border: 1px solid rgba(26,26,26,0.2);
    padding: 6px 12px;
    min-height: 40px;
    font-size: 0.8125rem;
  }
}

@media (max-width: 640px) {
  .header-inner {
    padding: 0 16px;
    height: 56px;
  }

  .wrap {
    padding: 0 16px;
  }

  .hero-section {
    min-height: 45vh;
    padding: 36px 0 28px;
  }

  .hero-inner {
    gap: 24px;
  }

  .hero-text h1 {
    font-size: 1.625rem;
  }

  .hero-icon {
    display: none;
  }

  .content-section {
    padding: 36px 0 56px;
  }

  .content-main h2 {
    margin-top: 40px;
  }

  .site-footer {
    padding: 36px 16px 24px;
  }

  .site-footer p.footer-cta {
    font-size: 1.0625rem;
  }

  div[id] {
    scroll-margin-top: 68px;
  }
}

@media (max-width: 375px) {
  body {
    font-size: 1rem;
  }

  .brand-logo-text {
    font-size: 1.0625rem;
  }

  .fullscreen-nav ol li a {
    font-size: 1rem;
    padding: 16px 32px;
  }
}