/* im体育官网 - style.css
   Motion Sports Lab + VR Training Arena + AI Fitness Game Interface
   HTML5 / CSS3 only, no external dependencies */

:root {
  --c-navy: #0a1830;
  --c-navy-2: #0f2445;
  --c-blue: #1657d1;
  --c-blue-2: #2f7dff;
  --c-cyan: #14c3c9;
  --c-orange: #ff7a33;
  --c-white: #ffffff;
  --c-bg: #f4f6fa;
  --c-bg-alt: #eef1f8;
  --c-text: #16202f;
  --c-text-muted: #5c6b80;
  --c-border: #e0e6f0;
  --c-card: #ffffff;
  --radius-s: 6px;
  --radius-m: 12px;
  --radius-l: 20px;
  --shadow-s: 0 2px 8px rgba(10, 24, 48, 0.06);
  --shadow-m: 0 8px 28px rgba(10, 24, 48, 0.10);
  --maxw: 1160px;
  --font: -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);
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--c-blue); text-decoration: none; }
a:hover { text-decoration: underline; }
ul, ol { padding-left: 1.3em; }
h1, h2, h3, h4 { line-height: 1.35; color: var(--c-navy); margin: 0 0 .6em; }
p { margin: 0 0 1em; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(10, 24, 48, 0.96);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--c-white); font-weight: 700; font-size: 1.15rem; }
.brand img { width: 34px; height: 34px; }
.brand small { display: block; font-weight: 400; font-size: .68rem; color: #9db3d6; letter-spacing: .04em; }
.main-nav { display: flex; align-items: center; gap: 2px; }
.main-nav a {
  color: #d7e2f5; padding: 10px 14px; border-radius: var(--radius-s);
  font-size: .92rem; white-space: nowrap;
}
.main-nav a:hover, .main-nav a[aria-current="page"] { color: var(--c-white); background: rgba(47,125,255,0.25); text-decoration: none; }
.nav-toggle {
  display: none; background: none; border: 1px solid rgba(255,255,255,0.3); border-radius: var(--radius-s);
  color: var(--c-white); width: 42px; height: 38px; font-size: 1.2rem; cursor: pointer;
}

/* ---------- Breadcrumb ---------- */
.breadcrumb { font-size: .85rem; color: var(--c-text-muted); padding: 14px 0; }
.breadcrumb a { color: var(--c-text-muted); }
.breadcrumb span[aria-current] { color: var(--c-navy); }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(135deg, var(--c-navy) 0%, var(--c-navy-2) 55%, #123a6b 100%);
  color: var(--c-white); padding: 56px 0 64px; position: relative; overflow: hidden;
}
.hero .container { display: grid; grid-template-columns: 1.1fr .9fr; gap: 40px; align-items: center; }
.hero h1 { color: var(--c-white); font-size: clamp(1.55rem, 3vw, 2.3rem); margin-bottom: .5em; }
.hero .lead { font-size: 1.12rem; color: #dfe8fb; margin-bottom: .6em; }
.hero .sub { color: #aebedd; font-size: .98rem; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 20px; }
.hero-tags span { background: rgba(47,125,255,0.18); border: 1px solid rgba(47,125,255,0.4); color: #cfe0ff; padding: 4px 12px; border-radius: 999px; font-size: .78rem; }
.hero-art { background: rgba(255,255,255,0.04); border: 1px solid rgba(255,255,255,0.12); border-radius: var(--radius-l); padding: 14px; }
.hero-art figcaption { text-align: center; color: #93a6c8; font-size: .76rem; margin-top: 8px; }

/* ---------- Page hero (subpages, simpler) ---------- */
.page-hero { background: linear-gradient(120deg, var(--c-navy), #14335f); color: var(--c-white); padding: 42px 0 46px; }
.page-hero h1 { color: var(--c-white); font-size: clamp(1.4rem, 2.6vw, 1.95rem); }
.page-hero p { color: #d7e2f5; max-width: 760px; font-size: 1.02rem; }

/* ---------- Sections ---------- */
.section { padding: 56px 0; }
.section-alt { background: var(--c-bg-alt); }
.section-head { max-width: 760px; margin-bottom: 30px; }
.section-head h2 { font-size: clamp(1.25rem, 2.2vw, 1.65rem); }
.section-head .kicker { display: inline-block; color: var(--c-cyan); font-weight: 700; font-size: .78rem; letter-spacing: .08em; text-transform: uppercase; margin-bottom: 8px; }
.section-head p { color: var(--c-text-muted); }

/* ---------- Article blocks (long-form) ---------- */
.article { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-l); padding: 32px clamp(18px,4vw,40px); margin-bottom: 26px; box-shadow: var(--shadow-s); }
.article .cat { display: inline-block; background: rgba(22,87,209,0.1); color: var(--c-blue); font-size: .76rem; font-weight: 700; padding: 4px 10px; border-radius: 999px; margin-bottom: 12px; }
.article h3 { font-size: clamp(1.1rem, 2vw, 1.38rem); }
.article h4 { font-size: 1.02rem; color: var(--c-blue); }
.article .figure { margin: 20px 0; background: var(--c-bg-alt); border-radius: var(--radius-m); padding: 16px; }
.article .figure figcaption { text-align: center; font-size: .8rem; color: var(--c-text-muted); margin-top: 8px; }
.article .note { font-size: .84rem; color: var(--c-text-muted); border-left: 3px solid var(--c-cyan); padding: 6px 12px; background: var(--c-bg-alt); border-radius: 0 var(--radius-s) var(--radius-s) 0; }
.article .related { margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--c-border); font-size: .88rem; }
.article .related strong { color: var(--c-navy); }

/* ---------- Observation column ---------- */
.observe-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.observe-card { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-m); padding: 24px; box-shadow: var(--shadow-s); }
.observe-card h3 { font-size: 1.02rem; }

/* ---------- Summary cards (feed back to homepage) ---------- */
.summary-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.summary-grid.cols-4 { grid-template-columns: repeat(4, 1fr); }
.summary-card { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-m); padding: 22px; box-shadow: var(--shadow-s); display: flex; flex-direction: column; }
.summary-card h4 { font-size: .98rem; }
.summary-card p { color: var(--c-text-muted); font-size: .88rem; flex-grow: 1; }
.summary-card a.more { font-size: .84rem; font-weight: 600; }

/* ---------- Cards / feature grid ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.feature-card { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-m); padding: 20px; box-shadow: var(--shadow-s); }
.feature-card .num { color: var(--c-cyan); font-weight: 800; font-size: .78rem; }
.feature-card h4 { font-size: .96rem; margin: 6px 0 4px; }
.feature-card p { font-size: .85rem; color: var(--c-text-muted); margin: 0; }

/* ---------- Pipeline diagram row ---------- */
.pipeline-row { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; justify-content: center; margin: 18px 0; }
.pipeline-row .step { background: var(--c-navy); color: #fff; padding: 8px 14px; border-radius: 999px; font-size: .82rem; white-space: nowrap; }
.pipeline-row .arrow { color: var(--c-cyan); font-weight: 700; }

/* ---------- Tabs (device switch) ---------- */
.tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 16px; }
.tab-btn { background: var(--c-bg-alt); border: 1px solid var(--c-border); padding: 8px 16px; border-radius: 999px; font-size: .86rem; cursor: pointer; color: var(--c-text); }
.tab-btn[aria-selected="true"] { background: var(--c-blue); color: #fff; border-color: var(--c-blue); }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ---------- FAQ ---------- */
.faq-list { border-top: 1px solid var(--c-border); }
.faq-item { border-bottom: 1px solid var(--c-border); }
.faq-q { width: 100%; text-align: left; background: none; border: 0; padding: 16px 4px; font-size: .98rem; font-weight: 600; color: var(--c-navy); cursor: pointer; display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.faq-q .icon { flex-shrink: 0; transition: transform .2s; color: var(--c-blue); }
.faq-q[aria-expanded="true"] .icon { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .25s ease; color: var(--c-text-muted); font-size: .92rem; }
.faq-a p { padding: 0 4px 16px; margin: 0; }

/* ---------- Training / adaptive demo widgets ---------- */
.demo-box { background: var(--c-navy); color: #fff; border-radius: var(--radius-l); padding: 26px; }
.demo-box h4 { color: #fff; }
.demo-row { display: flex; gap: 16px; flex-wrap: wrap; margin-top: 14px; }
.demo-stat { background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.14); border-radius: var(--radius-m); padding: 14px 18px; min-width: 140px; }
.demo-stat .label { font-size: .74rem; color: #9db3d6; text-transform: uppercase; letter-spacing: .05em; }
.demo-stat .value { font-size: 1.5rem; font-weight: 800; color: var(--c-cyan); }
.demo-btns { display: flex; gap: 10px; margin-top: 16px; flex-wrap: wrap; }
.demo-btns button { background: var(--c-blue); color: #fff; border: 0; padding: 8px 16px; border-radius: var(--radius-s); cursor: pointer; font-size: .85rem; }
.demo-btns button:hover { background: var(--c-blue-2); }
.demo-note { font-size: .8rem; color: #9db3d6; margin-top: 12px; }

/* ---------- App concept screen ---------- */
.app-screen { background: var(--c-navy); border-radius: 28px; padding: 20px; color: #fff; max-width: 320px; margin: 0 auto; border: 6px solid #06122a; }
.app-screen .tag { text-align: center; font-size: .7rem; color: #9db3d6; margin-bottom: 10px; }
.app-screen .row { display: flex; justify-content: space-between; align-items: center; background: rgba(255,255,255,0.06); border-radius: var(--radius-s); padding: 10px 12px; margin-bottom: 8px; font-size: .8rem; }
.app-screen .row .v { color: var(--c-cyan); font-weight: 800; }
.app-screen .caption { text-align: center; font-size: .74rem; color: #9db3d6; margin-top: 10px; }

/* ---------- Company / about ---------- */
.about-box { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-l); padding: 30px; }

/* ---------- Footer ---------- */
.site-footer { background: var(--c-navy); color: #b9c6de; padding: 46px 0 26px; font-size: .88rem; }
.footer-grid { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 28px; margin-bottom: 26px; }
.footer-grid h5 { color: #fff; font-size: .88rem; margin-bottom: 10px; }
.footer-grid ul { list-style: none; padding: 0; margin: 0; }
.footer-grid li { margin-bottom: 6px; }
.footer-grid a { color: #b9c6de; }
.footer-grid a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.1); padding-top: 18px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: .78rem; color: #8497b8; }
.icp-slot { color: #8497b8; }

/* ---------- Back to top ---------- */
.back-top {
  position: fixed; right: 20px; bottom: 20px; width: 44px; height: 44px; border-radius: 50%;
  background: var(--c-blue); color: #fff; border: 0; cursor: pointer; box-shadow: var(--shadow-m);
  display: none; align-items: center; justify-content: center; font-size: 1.1rem; z-index: 90;
}
.back-top.show { display: flex; }

/* ---------- SVG figure default ---------- */
.figure-standalone { background: var(--c-card); border: 1px solid var(--c-border); border-radius: var(--radius-l); padding: 20px; margin-bottom: 26px; }
.figure-standalone figcaption { text-align: center; color: var(--c-text-muted); font-size: .82rem; margin-top: 10px; }

table.compare { width: 100%; border-collapse: collapse; font-size: .9rem; margin: 16px 0; }
table.compare th, table.compare td { border: 1px solid var(--c-border); padding: 10px 12px; text-align: left; }
table.compare th { background: var(--c-bg-alt); color: var(--c-navy); }

/* ---------- Responsive ---------- */
@media (max-width: 1024px) {
  .hero .container { grid-template-columns: 1fr; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .observe-grid { grid-template-columns: 1fr; }
  .summary-grid, .summary-grid.cols-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 768px) {
  .main-nav { position: fixed; top: 68px; left: 0; right: 0; background: var(--c-navy); flex-direction: column; align-items: stretch; padding: 8px 14px 16px; gap: 0; max-height: 0; overflow: hidden; transition: max-height .25s ease; border-bottom: 1px solid rgba(255,255,255,0.08); }
  .main-nav.open { max-height: 480px; }
  .main-nav a { padding: 12px 6px; border-bottom: 1px solid rgba(255,255,255,0.06); }
  .nav-toggle { display: block; }
  .feature-grid { grid-template-columns: 1fr 1fr; }
  .summary-grid, .summary-grid.cols-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
}
@media (max-width: 430px) {
  .article { padding: 22px 16px; }
  .feature-grid { grid-template-columns: 1fr; }
  .app-screen { max-width: 100%; }
}