@import url('https://fonts.googleapis.com/css2?family=Caveat:wght@400;500;600;700&family=Quicksand:wght@300;400;500;600;700&display=swap');

/* ── 基础变量 ── */
:root {
  --c-black: #000000;
  --c-white: #ffffff;
  --c-gray-100: #f5f5f5;
  --c-gray-200: #e8e8e8;
  --c-gray-400: #999999;
  --c-gray-600: #555555;
  --c-accent: #000000;
  --c-accent-inv: #ffffff;

  --ff-sans: 'Quicksand', 'Helvetica Neue', Helvetica, Arial, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --ff-hand: 'Caveat', cursive;

  --base: 8px;
  --r-sm: 6px;
  --r-card: 10px;
  --r-pill: 999px;

  --nav-h: 64px;
  --header-h: 72px;

  --max-prose: 720px;
  --max-wrap: 1200px;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--ff-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--c-black);
  background: var(--c-white);
  padding-bottom: calc(var(--nav-h) + 16px);
}
img { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
a:hover { text-decoration: underline; }
ul, ol { list-style: none; }
button, input, textarea, select { font: inherit; }

/* ── Eyebrow / small 眉题 ── */
.eyebrow {
  display: block;
  font-family: var(--ff-sans);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-gray-400);
  margin-bottom: calc(var(--base) * 1);
}

/* ── Pill 按钮 ── */
.btn-pill {
  display: inline-block;
  padding: 10px 24px;
  border-radius: var(--r-pill);
  border: 2px solid var(--c-black);
  font-family: var(--ff-sans);
  font-size: 14px;
  font-weight: 600;
  background: transparent;
  color: var(--c-black);
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  min-height: 44px;
  line-height: 1;
  align-items: center;
  justify-content: center;
}
.btn-pill:hover {
  background: var(--c-black);
  color: var(--c-white);
  text-decoration: none;
}
.btn-pill--filled {
  background: var(--c-black);
  color: var(--c-white);
}
.btn-pill--filled:hover {
  background: var(--c-gray-600);
  border-color: var(--c-gray-600);
}

/* ══════════════════════════════════
   HERO
══════════════════════════════════ */
.hero {
  position: relative;
  min-height: 100vh;
  display: grid;
  grid-template-rows: auto 1fr;
  overflow: hidden;
  background: var(--c-black);
  color: var(--c-white);
}

.hero__text {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: calc(var(--base) * 10) calc(var(--base) * 4) calc(var(--base) * 6);
  gap: calc(var(--base) * 3);
}

.hero__title {
  font-family: var(--ff-sans);
  font-size: clamp(2rem, 6vw, 4rem);
  font-weight: 700;
  line-height: 1.15;
  color: var(--c-white);
  max-width: 800px;
}

.hero__sub {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  font-weight: 400;
  color: rgba(255,255,255,0.8);
  max-width: 560px;
  line-height: 1.7;
}

.hero__cta {
  border-color: var(--c-white);
  color: var(--c-white);
  margin-top: calc(var(--base) * 1);
}
.hero__cta:hover {
  background: var(--c-white);
  color: var(--c-black);
}

.hero__media {
  position: relative;
  z-index: 1;
  width: 100%;
  min-height: 300px;
  max-height: 60vh;
  overflow: hidden;
}
.hero__media .hero__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
}

/* ══════════════════════════════════
   MAIN WRAP
══════════════════════════════════ */
.main-wrap {
  max-width: var(--max-wrap);
  margin: 0 auto;
  padding: calc(var(--base) * 8) calc(var(--base) * 3);
}

.main-wrap--aside {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: calc(var(--base) * 6);
  align-items: start;
}

/* ── article / section 结构 ── */
.content-article {
  display: flex;
  flex-direction: column;
  gap: calc(var(--base) * 8);
  min-width: 0;
}

.content-section {
  width: 100%;
}

/* ══════════════════════════════════
   SIDEBAR
══════════════════════════════════ */
.sidebar {
  position: sticky;
  top: calc(var(--base) * 3);
  align-self: start;
}

.sidebar__inner {
  border-top: 3px solid var(--c-black);
  padding-top: calc(var(--base) * 2);
}

.sidebar__title {
  font-size: 14px;
  font-weight: 700;
  margin-bottom: calc(var(--base) * 2);
  letter-spacing: 0.02em;
}

.sidebar__links {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.sidebar__link {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--c-gray-600);
  padding: 6px 0;
  border-bottom: 1px solid var(--c-gray-200);
  transition: color 0.15s, padding-left 0.15s;
  line-height: 1.4;
}
.sidebar__link:hover,
.sidebar__link--active {
  color: var(--c-black);
  padding-left: 8px;
  text-decoration: none;
}

/* ══════════════════════════════════
   INNER HEADER
══════════════════════════════════ */
.inner-header {
  background: var(--c-black);
  color: var(--c-white);
  padding: calc(var(--base) * 8) calc(var(--base) * 3) calc(var(--base) * 6);
}

.inner-header__grid {
  max-width: var(--max-wrap);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: calc(var(--base) * 3);
  align-items: end;
}

.inner-header__label .eyebrow {
  color: rgba(255,255,255,0.5);
}

.inner-header__title h1 {
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--c-white);
}

/* ══════════════════════════════════
   PROSE / 正文排版
══════════════════════════════════ */
.prose {
  font-size: 16px;
  line-height: 1.75;
  color: var(--c-black);
  max-width: var(--max-prose);
}

.prose h2, .prose h3, .prose h4 {
  font-family: var(--ff-sans);
  font-weight: 700;
  margin: calc(var(--base) * 4) 0 calc(var(--base) * 2);
  line-height: 1.3;
}
.prose h2 { font-size: 1.5rem; border-bottom: 2px solid var(--c-black); padding-bottom: 6px; }
.prose h3 { font-size: 1.2rem; }
.prose h4 { font-size: 1rem; }

.prose p { margin-bottom: calc(var(--base) * 2); }
.prose ul, .prose ol { margin: calc(var(--base) * 2) 0 calc(var(--base) * 2) calc(var(--base) * 3); }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: calc(var(--base) * 1); }
.prose a { color: var(--c-black); font-weight: 600; text-decoration: underline; }
.prose a:hover { color: var(--c-gray-600); }
.prose strong { font-weight: 700; }
.prose em { font-style: italic; }
.prose blockquote {
  border-left: 4px solid var(--c-black);
  padding-left: calc(var(--base) * 2);
  margin: calc(var(--base) * 3) 0;
  color: var(--c-gray-600);
  font-style: italic;
}
.prose code {
  background: var(--c-gray-100);
  padding: 2px 6px;
  border-radius: var(--r-sm);
  font-size: 0.9em;
  font-family: 'Courier New', Courier, monospace;
}
.prose pre {
  background: var(--c-gray-100);
  padding: calc(var(--base) * 2);
  border-radius: var(--r-card);
  overflow-x: auto;
  margin: calc(var(--base) * 2) 0;
}
.prose pre code { background: transparent; padding: 0; }
.prose table { width: 100%; border-collapse: collapse; margin: calc(var(--base) * 3) 0; }
.prose th, .prose td { border: 1px solid var(--c-gray-200); padding: 8px 12px; text-align: left; font-size: 14px; }
.prose th { background: var(--c-black); color: var(--c-white); font-weight: 700; }

/* ══════════════════════════════════
   SECTION TITLE
══════════════════════════════════ */
.section-title {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  font-weight: 700;
  margin-bottom: calc(var(--base) * 4);
  line-height: 1.2;
}

/* ══════════════════════════════════
   CARDS GRID
══════════════════════════════════ */
.cards-section,
.faq-nav-section {
  width: 100%;
}

.cards-grid,
.faq-nav-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: calc(var(--base) * 3);
}

/* 子页列表：section > article×n（无列表标签）*/
.cards-grid > article,
.faq-nav-grid > article {
  display: block;
}

.card {
  border-radius: var(--r-card);
  border: 1px solid var(--c-gray-200);
  border-bottom: 3px solid var(--c-black);
  background: var(--c-white);
  overflow: hidden;
  transition: transform 0.2s, box-shadow 0.2s;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.1);
}

.card__link {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: calc(var(--base) * 3);
  color: var(--c-black);
}
.card__link:hover { text-decoration: none; }

.card__body {
  flex: 1;
}

.card__title {
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: calc(var(--base) * 1.5);
}

.card__desc {
  font-size: 13px;
  color: var(--c-gray-600);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card__foot {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: calc(var(--base) * 2);
  padding-top: calc(var(--base) * 1.5);
  border-top: 1px solid var(--c-gray-200);
}

.card__date {
  font-size: 11px;
  color: var(--c-gray-400);
  font-weight: 500;
}

.card__arrow {
  font-size: 18px;
  font-weight: 700;
  color: var(--c-black);
  transition: transform 0.2s;
}
.card:hover .card__arrow {
  transform: translateX(4px);
}

/* ══════════════════════════════════
   ARTICLE META
══════════════════════════════════ */
.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  font-size: 12px;
  color: var(--c-gray-400);
  margin-bottom: calc(var(--base) * 3);
  padding-bottom: calc(var(--base) * 2);
  border-bottom: 1px solid var(--c-gray-200);
}

.article-date {
  font-weight: 600;
  color: var(--c-gray-600);
}

.meta-label {
  color: var(--c-gray-400);
}

.meta-updated {
  font-size: 12px;
  color: var(--c-gray-400);
  margin-top: calc(var(--base) * 1);
}

.about-meta {
  border-top: 1px solid var(--c-gray-200);
  padding-top: calc(var(--base) * 3);
  font-size: 13px;
  color: var(--c-gray-600);
}

/* ══════════════════════════════════
   CONTACT FORM
══════════════════════════════════ */
.contact-form-section {
  max-width: 560px;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: calc(var(--base) * 2.5);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--c-black);
  letter-spacing: 0.03em;
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  border: 2px solid var(--c-gray-200);
  border-radius: var(--r-sm);
  font-size: 15px;
  background: var(--c-white);
  color: var(--c-black);
  transition: border-color 0.2s;
  outline: none;
}
.form-input:focus {
  border-color: var(--c-black);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

.form-submit {
  align-self: flex-start;
  min-height: 48px;
}

/* ══════════════════════════════════
   FOOTER
══════════════════════════════════ */
.site-footer {
  background: var(--c-black);
  color: var(--c-white);
  text-align: center;
  padding: calc(var(--base) * 3) calc(var(--base) * 3);
  margin-bottom: var(--nav-h);
}

.footer__copy {
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 4px;
}

.footer__note {
  font-size: 11px;
  color: rgba(255,255,255,0.5);
  display: block;
}

/* ══════════════════════════════════
   BOTTOM NAV（药丸胶囊，底部固定）
══════════════════════════════════ */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--c-white);
  border-top: 2px solid var(--c-black);
  height: var(--nav-h);
  display: flex;
  align-items: center;
  padding: 0 calc(var(--base) * 2);
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.bottom-nav::-webkit-scrollbar { display: none; }

.bottom-nav__list {
  display: flex;
  align-items: center;
  gap: calc(var(--base) * 1);
  width: 100%;
  list-style: none;
  flex-wrap: nowrap;
}

.bottom-nav__brand {
  flex-shrink: 0;
  margin-right: calc(var(--base) * 1);
}

.bottom-nav__logo-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--c-black);
  color: var(--c-white);
  font-size: 11px;
  font-weight: 700;
  text-align: center;
  line-height: 1.2;
  overflow: hidden;
  flex-shrink: 0;
}
.bottom-nav__logo-link:hover { text-decoration: none; opacity: 0.8; }
.bottom-nav__logo { width: 40px; height: 40px; object-fit: cover; }
.bottom-nav__logo-text { font-size: 10px; }

.bottom-nav__item {
  flex-shrink: 0;
}

.bottom-nav__link {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 40px;
  padding: 0 14px;
  border-radius: var(--r-pill);
  border: 1.5px solid var(--c-gray-200);
  font-size: 12px;
  font-weight: 600;
  color: var(--c-black);
  white-space: nowrap;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.bottom-nav__link:hover {
  background: var(--c-black);
  border-color: var(--c-black);
  color: var(--c-white);
  text-decoration: none;
}

.bottom-nav__link--pill {
  background: var(--c-black);
  border-color: var(--c-black);
  color: var(--c-white);
}
.bottom-nav__link--pill:hover {
  background: var(--c-gray-600);
  border-color: var(--c-gray-600);
}

/* ══════════════════════════════════
   SCROLL REVEAL 动效
══════════════════════════════════ */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.reveal.is-visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  .card { transition: none; }
  .card__arrow { transition: none; }
  .bottom-nav__link { transition: none; }
  .btn-pill { transition: none; }
}

/* ══════════════════════════════════
   响应式
══════════════════════════════════ */
@media (max-width: 900px) {
  .main-wrap--aside {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: static;
    border-top: none;
    border-bottom: 2px solid var(--c-black);
    padding-bottom: calc(var(--base) * 3);
    margin-bottom: calc(var(--base) * 2);
  }
  .inner-header__grid {
    grid-template-columns: 1fr;
    gap: calc(var(--base) * 1);
  }
}

@media (max-width: 600px) {
  :root {
    --nav-h: 60px;
  }
  body {
    font-size: 16px;
  }
  .hero__text {
    padding: calc(var(--base) * 8) calc(var(--base) * 2.5) calc(var(--base) * 5);
  }
  .hero__title {
    font-size: 1.75rem;
  }
  .hero__sub {
    font-size: 1rem;
  }
  .main-wrap {
    padding: calc(var(--base) * 5) calc(var(--base) * 2.5);
  }
  .inner-header {
    padding: calc(var(--base) * 6) calc(var(--base) * 2.5) calc(var(--base) * 4);
  }
  .cards-grid,
  .faq-nav-grid {
    grid-template-columns: 1fr;
  }
  .bottom-nav {
    padding: 0 calc(var(--base) * 1.5);
    gap: calc(var(--base) * 0.75);
  }
  .bottom-nav__link {
    padding: 0 10px;
    font-size: 11px;
  }
  .inner-header__grid {
    grid-template-columns: 1fr;
  }
  .contact-form-section {
    max-width: 100%;
  }
}

@media (min-width: 1024px) {
  .cards-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .faq-nav-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ══════════════════════════════════
   12列网格辅助（Swiss Grid）
══════════════════════════════════ */
.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1rem;
}