:root {
  --bg: #ffffff;
  --bg-alt: #f8f9fb;
  --text: #0d1117;
  --text-2: #3b4252;
  --text-3: #7c8596;
  --border: #e4e7ed;
  --border-light: #eef0f4;
  --accent: #009b72;
  --accent-light: #e6f7f1;
  --accent-border: #b8e4d4;
  --red: #d94040;
  --red-bg: #fef5f5;
  --radius: 10px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  color: var(--text-2);
  background: var(--bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  font-size: 15px;
}

/* ── Header ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  padding: 0 40px;
  background: rgba(255,255,255,.9);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
}

.brand {
  display: flex; align-items: center; gap: 10px;
  color: var(--text); font-weight: 700; font-size: 16px;
}
.brand-mark {
  display: flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; border-radius: 7px;
  background: var(--accent); color: #fff; font-size: 12px; font-weight: 800;
}

.nav { display: flex; gap: 2px; }
.nav a {
  padding: 6px 14px; border-radius: 6px;
  color: var(--text-3); font-size: 14px; font-weight: 500; transition: all .15s;
}
.nav a:hover { color: var(--text); background: #f4f5f7; }

/* ── Container ── */
.container { max-width: 960px; margin: 0 auto; padding: 0 40px; }

/* ── Hero (centered, no image column) ── */
.hero {
  padding: 100px 0 72px;
  text-align: center;
  background: linear-gradient(180deg, #f9fafb 0%, #fff 100%);
}

.hero-inner { max-width: 720px; margin: 0 auto; padding: 0 40px; }

.hero-inner h1 {
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -.025em;
  color: var(--text);
  margin-bottom: 24px;
}

.hero-inner h1 .hl {
  background: linear-gradient(135deg, var(--accent), #00c48c);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 17px; color: var(--text-3);
  max-width: 560px; margin: 0 auto 32px; line-height: 1.75;
}

.hero-cta { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; margin-bottom: 20px; }

.hero-note {
  font-size: 13px; color: #b4bac6;
}

/* ── Buttons ── */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  height: 44px; padding: 0 24px; border-radius: 8px;
  font-size: 14px; font-weight: 600; cursor: pointer; transition: all .2s;
}

.btn-primary {
  border: 1px solid var(--accent); background: var(--accent); color: #fff;
  box-shadow: 0 2px 10px rgba(0,155,114,.18);
}
.btn-primary:hover { background: #008a63; border-color: #008a63; color: #fff; }

.btn-outline {
  border: 1px solid var(--border); background: #fff; color: var(--text);
}
.btn-outline:hover { border-color: #c4cad4; background: #f9fafb; }

/* ── Sections ── */
.section { padding: 80px 0; }
.section-alt { background: var(--bg-alt); border-top: 1px solid var(--border-light); border-bottom: 1px solid var(--border-light); }

.section-title {
  font-size: 28px; font-weight: 700; color: var(--text);
  letter-spacing: -.01em; margin-bottom: 44px; line-height: 1.35;
}

/* ── Intro Grid ── */
.intro-grid {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 64px;
  align-items: start;
}

.intro-text h2 {
  font-size: 26px; font-weight: 700; color: var(--text);
  letter-spacing: -.01em; margin-bottom: 20px; line-height: 1.35;
}
.intro-text p {
  font-size: 15px; color: var(--text-2); line-height: 1.8; margin-bottom: 16px;
}
.intro-text p strong { color: var(--text); }

.intro-visual img { width: 100%; height: auto; }

/* ── Threat List ── */
.threat-list { display: flex; flex-direction: column; gap: 0; }

.threat-row {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 28px;
  padding: 28px 0;
  border-bottom: 1px solid var(--border-light);
  align-items: baseline;
}
.threat-row:first-child { border-top: 1px solid var(--border-light); }

.threat-badge {
  font-size: 12px; font-weight: 700; color: var(--accent);
  letter-spacing: .04em; padding-top: 2px;
}

.threat-content h3 {
  font-size: 17px; font-weight: 700; color: var(--text);
  margin-bottom: 6px; letter-spacing: -.01em;
}
.threat-content p {
  font-size: 14px; color: var(--text-3); line-height: 1.72;
}

/* ── Table ── */
.table-wrap {
  border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden;
}

table { width: 100%; border-collapse: collapse; min-width: 640px; }

th {
  padding: 14px 20px; text-align: left;
  font-size: 13px; font-weight: 700; color: var(--text-3);
  background: var(--bg-alt); border-bottom: 1px solid var(--border);
}
th.col-cold { color: var(--accent); }

td {
  padding: 14px 20px; font-size: 14px; color: var(--text-2);
  border-bottom: 1px solid var(--border-light); background: #fff;
}
td.row-label { font-weight: 600; color: var(--text); font-size: 13px; }
td.col-cold { color: var(--accent); font-weight: 600; }
td.col-bad  { color: var(--red); }

tr:last-child td { border-bottom: 0; }

/* ── Rules Grid ── */
.rules-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.rule-card {
  padding: 32px 28px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: #fff;
  position: relative;
}

.rule-num {
  font-size: 48px; font-weight: 800; color: #eef2f6;
  line-height: 1; margin-bottom: 16px; letter-spacing: -.02em;
}

.rule-card h3 {
  font-size: 16px; font-weight: 700; color: var(--text);
  margin-bottom: 12px; line-height: 1.5; letter-spacing: -.01em;
}

.rule-card p {
  font-size: 14px; color: var(--text-3); line-height: 1.7;
  margin-bottom: 16px;
}

.rule-tag {
  display: inline-block;
  padding: 4px 10px; border-radius: 4px;
  font-size: 11px; font-weight: 600; color: var(--accent);
  background: var(--accent-light);
}

/* ── FAQ ── */
.faq-list { max-width: 720px; }

.faq-item {
  border-bottom: 1px solid var(--border-light);
}
.faq-item:first-child { border-top: 1px solid var(--border-light); }

.faq-q {
  cursor: pointer;
  display: flex; align-items: center; justify-content: space-between;
  padding: 20px 0; gap: 16px; user-select: none;
  font-size: 15px; font-weight: 600; color: var(--text);
}

.faq-arrow {
  flex-shrink: 0;
  width: 22px; height: 22px; border-radius: 5px;
  display: flex; align-items: center; justify-content: center;
  font-size: 15px; color: var(--text-3); background: #f5f6f8;
  transition: transform .2s;
}

.faq-item.open .faq-arrow { transform: rotate(45deg); }

.faq-a {
  display: none;
  padding: 0 0 20px;
  font-size: 14px; color: var(--text-3); line-height: 1.75;
}

.faq-item.open .faq-a { display: block; }

/* ── Footer ── */
.footer {
  padding: 28px 0;
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
}

.footer .container {
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 8px;
}

.footer p { font-size: 13px; color: var(--text-3); }

/* ── Responsive ── */
@media (max-width: 860px) {
  .site-header { padding: 0 20px; }
  .container { padding: 0 20px; }
  .nav { overflow-x: auto; }

  .intro-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .intro-visual { max-width: 280px; }

  .rules-grid { grid-template-columns: 1fr; }

  .threat-row {
    grid-template-columns: 1fr;
    gap: 8px;
    padding: 22px 0;
  }

  .hero { padding: 64px 0 48px; }
  .section { padding: 56px 0; }
  .section-title { font-size: 24px; margin-bottom: 32px; }
}

@media (max-width: 520px) {
  .site-header { flex-direction: column; height: auto; padding: 10px 16px; gap: 8px; align-items: flex-start; }
  .hero-inner h1 { font-size: 30px; }
  .btn { width: 100%; }
}