:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --surface-2: #f0f3f9;
  --text: #0f172a;
  --muted: #5b6675;
  --accent: #3b5bfd;
  --accent-2: #1aa67a;
  --border: #e3e8f0;
  --code-bg: #0e1116;
  --code: #c9d1d9;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

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

/* ---------- Nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: 1120px; margin: 0 auto; padding: 12px 22px;
  display: flex; align-items: center; gap: 24px;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; }
.logo {
  background: var(--accent); color: #fff;
  padding: 5px 10px; border-radius: 8px; font-size: 15px; letter-spacing: 1px;
}
.brand-name { font-size: 17px; }
.nav-links { display: flex; gap: 22px; margin-left: 12px; flex: 1; }
.nav-links a { color: var(--muted); font-size: 14px; }
.nav-links a:hover { color: var(--text); }
.nav-cta {
  background: var(--accent); color: #fff;
  padding: 8px 16px; border-radius: 999px; font-size: 14px; font-weight: 600;
}
.nav-cta:hover { filter: brightness(1.07); }

/* ---------- Hero ---------- */
.hero {
  background: radial-gradient(1200px 500px at 70% -10%, #dfe6ff 0%, transparent 60%),
              linear-gradient(180deg, #eef2ff, var(--bg));
  padding: 72px 22px 64px;
}
.hero-inner { max-width: 880px; margin: 0 auto; text-align: center; }
.badge {
  display: inline-block; padding: 6px 14px; border-radius: 999px;
  background: #fff; border: 1px solid var(--border); color: var(--accent);
  font-size: 13px; font-weight: 600; margin-bottom: 18px;
}
.hero h1 {
  font-size: 44px; line-height: 1.2; margin: 0 0 18px; letter-spacing: -0.5px;
}
.hero-sub { font-size: 17px; color: var(--muted); max-width: 720px; margin: 0 auto 26px; }
.hero-sub b { color: var(--text); }
.hero-actions { display: flex; gap: 14px; justify-content: center; margin-bottom: 28px; }
.btn-primary {
  background: var(--accent); color: #fff; padding: 12px 26px;
  border-radius: 10px; font-weight: 700; font-size: 15px;
}
.btn-primary:hover { filter: brightness(1.07); }
.btn-ghost {
  border: 1px solid var(--border); color: var(--text);
  padding: 12px 26px; border-radius: 10px; font-weight: 600; font-size: 15px; background: #fff;
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }
.hero-engines { font-size: 13px; color: var(--muted); }

/* ---------- Sections ---------- */
.section { max-width: 1120px; margin: 0 auto; padding: 64px 22px; }
.section--alt { max-width: none; background: var(--surface); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section--alt > * { max-width: 1120px; margin-left: auto; margin-right: auto; }
.section-head { text-align: center; max-width: 720px; margin: 0 auto 40px; }
.section-head h2 { font-size: 30px; margin: 0 0 12px; }
.section-head p { color: var(--muted); font-size: 16px; margin: 0; }

/* intro */
.intro-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.intro-card { background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 22px; box-shadow: var(--shadow); }
.intro-card h3 { margin: 0 0 8px; font-size: 18px; }
.intro-card p { margin: 0; color: var(--muted); font-size: 14.5px; }

/* features */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature-card { background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 24px; box-shadow: var(--shadow); }
.feature-num { color: var(--accent); font-weight: 800; font-size: 14px; letter-spacing: 1px; }
.feature-card h3 { margin: 8px 0 10px; font-size: 19px; }
.feature-card p { margin: 0; color: var(--muted); font-size: 14.5px; }

/* cases */
.case-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.case-card { background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 24px; box-shadow: var(--shadow); }
.case-name { font-weight: 700; font-size: 17px; margin-bottom: 10px; }
.case-score { font-size: 22px; font-weight: 800; margin-bottom: 12px; }
.case-score .before { color: #c0392b; }
.case-score .after { color: var(--accent-2); }
.case-score em { color: var(--accent-2); font-style: normal; font-size: 16px; margin-left: 6px; }
.bar { display: flex; gap: 4px; height: 10px; background: var(--surface-2); border-radius: 999px; overflow: hidden; margin-bottom: 12px; }
.bar i { display: block; height: 100%; background: #c0392b; }
.bar i.after { background: var(--accent-2); }
.case-card p { margin: 0; color: var(--muted); font-size: 13.5px; }

/* ---------- Console ---------- */
.console {
  background: var(--code-bg); border-radius: 16px; overflow: hidden;
  box-shadow: var(--shadow); border: 1px solid #1c2330;
}
.console-bar {
  display: flex; align-items: center; gap: 8px;
  padding: 12px 16px; background: #161b22; border-bottom: 1px solid #1c2330;
}
.console-bar .dot { width: 11px; height: 11px; border-radius: 50%; background: #3a4250; }
.console-bar .dot:nth-child(1) { background: #ff5f57; }
.console-bar .dot:nth-child(2) { background: #febc2e; }
.console-bar .dot:nth-child(3) { background: #28c840; }
.engine-status { margin-left: auto; font-size: 12.5px; padding: 5px 12px; border-radius: 999px; border: 1px solid #2a3340; color: var(--muted); }
.status { margin-left: auto; font-size: 12.5px; padding: 5px 12px; border-radius: 999px; border: 1px solid #2a3340; color: var(--muted); }
.status--idle { color: var(--muted); }
.status--loading { color: #f0c674; border-color: #5a4a1f; }
.status--ready { color: #3fb950; border-color: #1f4a2a; }
.status--err { color: #ff6b6b; border-color: #5a1f1f; }

.console-body { display: grid; grid-template-columns: minmax(320px, 440px) 1fr; gap: 0; }
@media (max-width: 900px) { .console-body { grid-template-columns: 1fr; } }
.panel { padding: 18px; }
.panel.control { background: #11161d; border-right: 1px solid #1c2330; }
.panel.output { background: #0e1116; }

.field { margin-bottom: 14px; }
.field label { display: block; font-size: 12.5px; color: #8b97a7; margin-bottom: 6px; }
.field code, .hint code, .args code, .io code { background: #0b0e13; padding: 1px 6px; border-radius: 4px; color: var(--code); font-size: 12px; }

.args {
  width: 100%; padding: 10px 12px; background: #0b0e13; border: 1px solid #2a3340;
  border-radius: 8px; color: #e6edf3; font-family: ui-monospace, Menlo, monospace; font-size: 13px;
}
.io {
  width: 100%; min-height: 110px; padding: 10px 12px; background: #0b0e13;
  border: 1px solid #2a3340; border-radius: 8px; color: #e6edf3;
  font-family: ui-monospace, Menlo, monospace; font-size: 12.5px; resize: vertical;
}

.presets { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 14px; }
.presets button {
  background: #1c2330; border: 1px solid #2a3340; color: #e6edf3;
  padding: 6px 10px; border-radius: 8px; font-size: 12px; cursor: pointer;
}
.presets button:hover { border-color: var(--accent); }

.run {
  width: 100%; padding: 11px; background: var(--accent); color: #fff;
  border: none; border-radius: 8px; font-size: 14px; font-weight: 600; cursor: pointer;
}
.run:hover { filter: brightness(1.08); }
.run:disabled { opacity: 0.5; cursor: not-allowed; }
.hint { font-size: 11.5px; color: #8b97a7; margin: 10px 0 0; }

.tabs { display: flex; gap: 8px; margin-bottom: 10px; }
.tab {
  background: transparent; border: 1px solid #2a3340; color: #8b97a7;
  padding: 6px 12px; border-radius: 8px; font-size: 12.5px; cursor: pointer;
}
.tab--active { color: #e6edf3; border-color: var(--accent); }

.stdout {
  margin: 0; white-space: pre-wrap; word-break: break-word;
  font-family: ui-monospace, Menlo, monospace; font-size: 12.5px; color: var(--code);
  background: #0b0e13; border: 1px solid #2a3340; border-radius: 8px;
  padding: 14px; max-height: 60vh; overflow: auto; min-height: 320px;
}
.files { display: flex; flex-direction: column; gap: 12px; }
.file-card { background: #0b0e13; border: 1px solid #2a3340; border-radius: 8px; overflow: hidden; }
.file-head { display: flex; align-items: center; justify-content: space-between; padding: 8px 12px; border-bottom: 1px solid #2a3340; font-size: 12.5px; }
.file-head .name { font-family: ui-monospace, monospace; color: #58a6ff; }
.file-head a { color: #3fb950; text-decoration: none; font-size: 12px; }
.file-body {
  margin: 0; padding: 12px; max-height: 40vh; overflow: auto;
  font-family: ui-monospace, monospace; font-size: 12px; color: var(--code);
  white-space: pre-wrap; word-break: break-word;
}
.file-body .render, .file-body iframe { width: 100%; min-height: 320px; border: 0; background: #fff; }

/* ---------- Footer ---------- */
.footer { background: #0e1116; color: #c9d1d9; margin-top: 0; }
.footer-inner { max-width: 1120px; margin: 0 auto; padding: 48px 22px 28px; display: flex; justify-content: space-between; gap: 30px; flex-wrap: wrap; }
.footer-brand { display: flex; align-items: center; gap: 10px; font-weight: 700; }
.footer-brand .logo { background: var(--accent); }
.footer-cols { display: flex; gap: 56px; }
.footer-cols h4 { margin: 0 0 12px; font-size: 14px; color: #fff; }
.footer-cols a, .footer-cols span { display: block; color: #8b97a7; font-size: 13.5px; margin-bottom: 8px; }
.footer-cols a:hover { color: #fff; }
.footer-bottom { max-width: 1120px; margin: 0 auto; padding: 18px 22px; border-top: 1px solid #1c2330; color: #6b7686; font-size: 13px; text-align: center; }

@media (max-width: 760px) {
  .nav-links { display: none; }
  .hero h1 { font-size: 32px; }
  .intro-grid, .feature-grid, .case-grid { grid-template-columns: 1fr; }
}