/* ==========================================================================
   买球网官网 - 全站样式
   Sports Technology Forum + AI Research Desk + Community Knowledge Base
   ========================================================================== */

:root {
  --color-bg: #FAF7F1;
  --color-surface: #FFFFFF;
  --color-surface-alt: #F3EFE7;
  --color-ink: #262A2E;
  --color-ink-soft: #565C63;
  --color-ink-faint: #868D95;
  --color-border: #E4DFD4;
  --color-border-soft: #ECE7DB;

  --color-primary: #123A6B;
  --color-primary-dark: #0B2647;
  --color-primary-soft: #E7EEF7;
  --color-cyan: #0E9FAE;
  --color-cyan-soft: #E3F5F6;
  --color-orange: #E2712F;
  --color-orange-soft: #FCEEE2;
  --color-graphite: #3B4148;

  --color-ai-bg: #EEF4FB;
  --color-ai-border: #C7D9EE;
  --color-ai-tag: #16549A;

  --color-human-bg: #FFFFFF;
  --color-human-border: #E7D9C6;
  --color-human-tag: #B75A1F;

  --evidence-official: #16549A;
  --evidence-research: #0E9FAE;
  --evidence-manufacturer: #8A5CB8;
  --evidence-media: #B75A1F;
  --evidence-community: #3F8A4B;
  --evidence-inference: #868D95;

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --shadow-card: 0 2px 14px rgba(18, 58, 107, 0.07);
  --shadow-card-hover: 0 8px 26px rgba(18, 58, 107, 0.12);
  --max-width: 1160px;

  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-ink);
  line-height: 1.75;
  font-size: 16px;
  overflow-x: hidden;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
ul, ol { padding-left: 1.3em; }
h1, h2, h3, h4 { line-height: 1.4; margin: 0 0 .6em; color: var(--color-primary-dark); }
p { margin: 0 0 1em; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- Skip link ---------- */
.skip-link {
  position: absolute; left: -999px; top: 0;
  background: var(--color-primary); color: #fff; padding: 10px 16px; z-index: 999;
}
.skip-link:focus { left: 10px; top: 10px; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(250, 247, 241, 0.96);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--color-border);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  max-width: var(--max-width); margin: 0 auto; padding: 12px 20px;
}
.nav-logo {
  display: flex; align-items: center; gap: 8px;
  font-weight: 700; font-size: 20px; color: var(--color-primary-dark);
}
.nav-logo:hover { text-decoration: none; }
.nav-logo .logo-mark { width: 34px; height: 34px; flex-shrink: 0; }
.nav-links {
  display: flex; gap: 4px; list-style: none; margin: 0; padding: 0;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--color-graphite); font-size: 14.5px; padding: 8px 12px;
  border-radius: var(--radius-sm); display: inline-block;
}
.nav-links a:hover, .nav-links a[aria-current="page"] {
  background: var(--color-primary-soft); color: var(--color-primary); text-decoration: none;
}
.nav-toggle {
  display: none; background: none; border: 1px solid var(--color-border);
  border-radius: var(--radius-sm); padding: 6px 10px; font-size: 20px; cursor: pointer;
}

@media (max-width: 860px) {
  .nav-toggle { display: inline-block; }
  .nav-links {
    display: none; flex-direction: column; width: 100%;
    background: var(--color-surface); border-top: 1px solid var(--color-border);
    padding: 8px 0; position: absolute; left: 0; right: 0; top: 100%;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 20px; border-radius: 0; }
  .nav { position: relative; flex-wrap: wrap; }
}

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(160deg, var(--color-primary-dark) 0%, var(--color-primary) 62%, var(--color-cyan) 130%);
  color: #F3F7FC;
  padding: 52px 0 46px;
}
.hero .container { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 40px; align-items: center; }
.hero-badge {
  display: inline-block; background: rgba(255,255,255,0.14); border: 1px solid rgba(255,255,255,0.3);
  color: #EAF2FF; font-size: 13px; padding: 5px 12px; border-radius: 999px; margin-bottom: 14px;
}
.hero h1 { color: #fff; font-size: 30px; margin-bottom: 14px; }
.hero-principle {
  background: rgba(255,255,255,0.1); border-left: 3px solid var(--color-cyan);
  padding: 10px 16px; border-radius: var(--radius-sm); font-size: 15.5px; margin-bottom: 16px; color: #EAF2FF;
}
.hero-text { color: #DCE8F7; font-size: 15.5px; }
.hero-actions { margin-top: 18px; display: flex; gap: 10px; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 10px 20px; border-radius: 999px; font-size: 14.5px;
  font-weight: 600; cursor: pointer; border: 1px solid transparent;
}
.btn-primary { background: #fff; color: var(--color-primary-dark); }
.btn-primary:hover { background: #EAF2FF; text-decoration: none; }
.btn-outline { background: transparent; color: #fff; border-color: rgba(255,255,255,0.6); }
.btn-outline:hover { background: rgba(255,255,255,0.12); text-decoration: none; }
.hero-visual { background: rgba(255,255,255,0.08); border-radius: var(--radius-lg); padding: 14px; }
.hero-visual img { border-radius: var(--radius-md); }

@media (max-width: 860px) {
  .hero .container { grid-template-columns: 1fr; }
}

/* ---------- Page header (secondary pages) ---------- */
.page-header {
  background: linear-gradient(160deg, var(--color-primary-dark), var(--color-primary));
  color: #fff; padding: 40px 0 34px;
}
.page-header .breadcrumb { color: #C9DAF0; font-size: 13px; margin-bottom: 10px; }
.page-header .breadcrumb a { color: #DCE8F7; }
.page-header h1 { color: #fff; font-size: 27px; margin-bottom: 10px; }
.page-header p { color: #DCE8F7; max-width: 760px; font-size: 15px; }

/* ---------- Sections ---------- */
.section { padding: 46px 0; }
.section-alt { background: var(--color-surface-alt); }
.section-head { max-width: 760px; margin-bottom: 26px; }
.section-eyebrow {
  text-transform: uppercase; letter-spacing: .06em; font-size: 12.5px; font-weight: 700;
  color: var(--color-cyan); margin-bottom: 6px; display: block;
}
.section-title { font-size: 24px; margin-bottom: 8px; }
.section-sub { color: var(--color-ink-soft); font-size: 15px; }

/* ---------- News grid ---------- */
.news-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; }
.news-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); padding: 18px; box-shadow: var(--shadow-card);
}
.news-card .news-tag { font-size: 12px; color: var(--color-cyan); font-weight: 700; }
.news-card h3 { font-size: 16px; margin: 6px 0 8px; }
.news-card p { font-size: 14px; color: var(--color-ink-soft); margin-bottom: 0; }

/* ---------- Article blocks (long-form) ---------- */
.article-block {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); padding: 30px 32px; margin-bottom: 28px;
  box-shadow: var(--shadow-card);
  scroll-margin-top: 90px;
}
.article-meta {
  display: flex; gap: 10px; align-items: center; flex-wrap: wrap;
  font-size: 12.5px; color: var(--color-ink-faint); margin-bottom: 10px;
}
.article-meta .cat { color: var(--color-primary); font-weight: 700; background: var(--color-primary-soft); padding: 3px 10px; border-radius: 999px; }
.article-block h2 { font-size: 21px; }
.article-block h3.article-title { font-size: 20px; }
.article-body p { font-size: 15.3px; color: #333; }
.article-body strong { color: var(--color-primary-dark); }
.article-quote {
  border-left: 3px solid var(--color-orange); background: var(--color-orange-soft);
  padding: 12px 16px; margin: 16px 0; font-size: 14.8px; border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: #5a3418;
}
.article-diagram { margin: 18px 0; text-align: center; }
.article-diagram figcaption { font-size: 12.5px; color: var(--color-ink-faint); margin-top: 6px; }
.article-related {
  margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--color-border);
  font-size: 13.5px; color: var(--color-ink-soft);
}
.article-related a { margin-right: 12px; }

/* ---------- Summary cards (index page, 21 articles) ---------- */
.summary-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 18px; }
.summary-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); padding: 20px; box-shadow: var(--shadow-card);
  display: flex; flex-direction: column;
}
.summary-card .summary-tag {
  font-size: 12px; font-weight: 700; color: #fff; background: var(--color-cyan);
  padding: 3px 10px; border-radius: 999px; align-self: flex-start; margin-bottom: 10px;
}
.summary-card h3 { font-size: 16px; margin-bottom: 8px; }
.summary-card p { font-size: 13.8px; color: var(--color-ink-soft); flex-grow: 1; }
.summary-card .summary-link { font-size: 13.5px; font-weight: 600; margin-top: 10px; }

/* ---------- AI card vs Human discussion card ---------- */
.ai-card {
  background: var(--color-ai-bg); border: 1px solid var(--color-ai-border);
  border-left: 4px solid var(--color-ai-tag);
  border-radius: var(--radius-md); padding: 18px 20px; margin: 16px 0;
}
.ai-card .ai-card-label {
  display: inline-flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 700;
  color: var(--color-ai-tag); text-transform: uppercase; letter-spacing: .04em; margin-bottom: 8px;
}
.ai-card .ai-card-label::before { content: "◆"; font-size: 10px; }
.ai-card h4 { font-size: 15px; margin: 10px 0 4px; color: var(--color-ai-tag); }
.ai-card p, .ai-card li { font-size: 14.2px; color: #2c3a4d; }
.ai-card .updated {
  font-size: 12px; color: #4a6488; margin-top: 10px; border-top: 1px dashed var(--color-ai-border);
  padding-top: 8px;
}

.discussion-card {
  background: var(--color-human-bg); border: 1px solid var(--color-human-border);
  border-left: 4px solid var(--color-human-tag);
  border-radius: var(--radius-md); padding: 18px 20px; margin: 16px 0;
}
.discussion-card .discussion-label {
  display: inline-flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 700;
  color: var(--color-human-tag); text-transform: uppercase; letter-spacing: .04em; margin-bottom: 8px;
}
.discussion-card .discussion-label::before { content: "●"; font-size: 10px; }
.opinion-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 12px; margin-top: 10px; }
.opinion-item { background: var(--color-surface-alt); border-radius: var(--radius-sm); padding: 12px 14px; font-size: 14px; }
.opinion-item .opinion-label { font-weight: 700; color: var(--color-human-tag); display: block; margin-bottom: 4px; font-size: 13.5px; }

/* ---------- Evidence tags ---------- */
.evidence-tag {
  display: inline-block; font-size: 12px; font-weight: 700; padding: 2px 9px;
  border-radius: 999px; color: #fff; margin-right: 6px; margin-bottom: 4px;
}
.evidence-official { background: var(--evidence-official); }
.evidence-research { background: var(--evidence-research); }
.evidence-manufacturer { background: var(--evidence-manufacturer); }
.evidence-media { background: var(--evidence-media); }
.evidence-community { background: var(--evidence-community); }
.evidence-inference { background: var(--evidence-inference); }

/* ---------- Topic / term / archive / feature cards ---------- */
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 18px; }
.topic-card, .wiki-term-card, .archive-card, .feature-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); padding: 20px; box-shadow: var(--shadow-card);
}
.topic-card h3, .wiki-term-card h3, .archive-card h3, .feature-card h3 { font-size: 16.5px; }
.topic-card .topic-meta, .archive-card .archive-meta { font-size: 12.5px; color: var(--color-ink-faint); margin-bottom: 8px; }
.feature-card .feature-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; border-radius: 50%; background: var(--color-primary-soft);
  color: var(--color-primary); font-weight: 700; font-size: 13px; margin-bottom: 10px;
}

/* ---------- Filter tabs ---------- */
.filter-tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.filter-tab {
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: 999px;
  padding: 7px 16px; font-size: 13.5px; cursor: pointer; color: var(--color-graphite);
}
.filter-tab.active { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.filter-item { display: none; }
.filter-item.show { display: block; }
.filter-item.show.grid-item { display: block; }

/* ---------- Rules list ---------- */
.rules-list { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(260px,1fr)); gap: 12px; }
.rules-list li {
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-sm);
  padding: 12px 14px; font-size: 14px;
}
.rules-list li::before { content: "✓ "; color: var(--color-cyan); font-weight: 700; }

/* ---------- FAQ ---------- */
.faq-list { border-top: 1px solid var(--color-border); }
.faq-item { border-bottom: 1px solid var(--color-border); }
.faq-question {
  width: 100%; text-align: left; background: none; border: none; cursor: pointer;
  padding: 16px 4px; font-size: 15.5px; font-weight: 600; color: var(--color-primary-dark);
  display: flex; justify-content: space-between; align-items: center; gap: 12px;
}
.faq-question .icon { transition: transform .2s ease; flex-shrink: 0; color: var(--color-cyan); }
.faq-item.open .faq-question .icon { transform: rotate(45deg); }
.faq-answer {
  max-height: 0; overflow: hidden; transition: max-height .25s ease;
  font-size: 14.5px; color: var(--color-ink-soft); padding: 0 4px;
}
.faq-item.open .faq-answer { max-height: 400px; padding-bottom: 16px; }

/* ---------- About ---------- */
.about-block {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); padding: 30px 32px;
}
.about-block .company-line { font-weight: 700; color: var(--color-primary-dark); margin-bottom: 10px; font-size: 16px; }

/* ---------- Footer ---------- */
.site-footer { background: var(--color-primary-dark); color: #C9D6E8; padding: 40px 0 18px; margin-top: 20px; }
.footer-cols { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 24px; padding-bottom: 24px; border-bottom: 1px solid rgba(255,255,255,0.14); }
.footer-cols h4 { color: #fff; font-size: 14.5px; margin-bottom: 10px; }
.footer-cols ul { list-style: none; padding: 0; margin: 0; }
.footer-cols li { margin-bottom: 8px; font-size: 13.8px; }
.footer-cols a { color: #C9D6E8; }
.footer-cols a:hover { color: #fff; }
.footer-bottom { padding-top: 18px; font-size: 12.8px; color: #9FB0C6; text-align: center; line-height: 1.9; }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed; right: 20px; bottom: 20px; width: 42px; height: 42px; border-radius: 50%;
  background: var(--color-primary); color: #fff; border: none; cursor: pointer; font-size: 18px;
  box-shadow: var(--shadow-card-hover); display: none; z-index: 90;
}
.back-to-top.show { display: block; }

/* ---------- Utility ---------- */
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; }
.pill { background: var(--color-surface-alt); border-radius: 999px; padding: 4px 12px; font-size: 12.8px; color: var(--color-ink-soft); }
.mt-0 { margin-top: 0; }
.small-note { font-size: 12.8px; color: var(--color-ink-faint); }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
@media (max-width: 760px) {
  .two-col { grid-template-columns: 1fr; }
  .article-block { padding: 22px 18px; }
  .hero h1 { font-size: 24px; }
  .section-title { font-size: 20px; }
}