/* ═══════════════════════════════════════════════════════════
   AI API Doctor — website stylesheet
   Mobile-first, receipt-style, bilingual zh-CN / en-US
   ═══════════════════════════════════════════════════════════ */

/* ── Design Tokens ──────────────────────────────────── */
:root {
  --bg: #f8fafc;
  --panel: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --soft: #f1f5f9;
  --border: #e2e8f0;

  --success: #16a34a;
  --success-bg: #dcfce7;
  --warning: #f59e0b;
  --warning-bg: #fef3c7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --info: #2563eb;
  --info-bg: #dbeafe;

  --accent: #0f172a;
  --accent-hover: #1e293b;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --mono: 'SF Mono', 'Cascadia Code', Consolas, 'Liberation Mono', monospace;

  --radius: 12px;
  --radius-sm: 8px;
  --radius-lg: 16px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.1), 0 8px 16px rgba(0,0,0,0.06);
}

/* ── Reset ──────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; }
a { color: var(--info); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Layout ─────────────────────────────────────────── */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 20px;
}
.container--narrow { max-width: 760px; }

/* ── Header ─────────────────────────────────────────── */
.site-header {
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  gap: 16px;
}
.site-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
}
.site-logo:hover { text-decoration: none; }
.site-logo__icon {
  width: 32px;
  height: 32px;
  background: var(--info);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.site-logo__icon svg { width: 18px; height: 18px; color: #fff; }

.site-nav { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.site-nav a {
  display: inline-flex;
  align-items: center;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  transition: color 0.15s, background 0.15s;
}
.site-nav a:hover { color: var(--text); background: var(--soft); text-decoration: none; }
.site-nav a.active { color: var(--info); }

/* ── Language switcher ────────────────────────────── */
.lang-switcher {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 13px;
  white-space: nowrap;
  flex-shrink: 0;
}
.lang-switcher__current {
  font-weight: 700;
  color: var(--text);
  cursor: default;
}
.lang-switcher__sep {
  color: var(--border);
  margin: 0 2px;
}
.lang-switcher__link {
  color: var(--info);
  font-weight: 500;
}
.lang-switcher__link:hover {
  text-decoration: underline;
}

/* ── Mobile nav toggle ──────────────────────────────── */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: 8px;
  color: var(--text);
  border-radius: var(--radius-sm);
}
.nav-toggle:hover { background: var(--soft); }

/* ── Footer ─────────────────────────────────────────── */
.site-footer {
  background: var(--panel);
  border-top: 1px solid var(--border);
  padding: 32px 0;
  margin-top: 80px;
}
.site-footer__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  text-align: center;
  font-size: 13px;
  color: var(--muted);
}
.site-footer__links { display: flex; gap: 16px; flex-wrap: wrap; justify-content: center; }
.site-footer__links a { color: var(--muted); font-size: 13px; }
.site-footer__links a:hover { color: var(--text); }
.site-footer__note {
  font-size: 12px;
  color: #94a3b8;
  max-width: 480px;
  line-height: 1.6;
  margin-top: 8px;
}

/* ── Buttons ─────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: opacity 0.15s, background 0.15s;
  text-decoration: none;
  min-height: 44px;
  font-family: var(--font);
}
.btn:hover { text-decoration: none; opacity: 0.88; }
.btn--primary { background: var(--info); color: #fff; }
.btn--secondary { background: var(--soft); color: var(--text); border: 1px solid var(--border); }
.btn--outline { background: transparent; color: var(--info); border: 1px solid var(--info); }
.btn--danger { background: var(--danger); color: #fff; }
.btn--sm { padding: 8px 16px; font-size: 13px; min-height: 36px; }
.btn--lg { padding: 14px 28px; font-size: 16px; min-height: 52px; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn svg { width: 16px; height: 16px; flex-shrink: 0; }
.btn--icon-only { padding: 10px; min-height: 44px; min-width: 44px; }

/* ── Cards ─────────────────────────────────────────── */
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow);
}
.card--flat { box-shadow: none; }
.card__title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text);
}
.card__desc { font-size: 14px; color: var(--muted); line-height: 1.6; }

/* ── Badges / Status ─────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.3px;
}
.badge--success { background: var(--success-bg); color: var(--success); }
.badge--warning { background: var(--warning-bg); color: var(--warning); }
.badge--danger { background: var(--danger-bg); color: var(--danger); }
.badge--info { background: var(--info-bg); color: var(--info); }
.badge--neutral { background: var(--soft); color: var(--muted); }

/* ── Report Card ─────────────────────────────────── */
.billing-report-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  max-width: 640px;
  margin: 0 auto;
  font-size: 14px;
}
.report-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 20px;
  gap: 12px;
}
.report-header__brand { font-size: 18px; font-weight: 700; color: var(--text); }
.report-header__sub { font-size: 13px; color: var(--muted); margin-top: 2px; }
.report-header__meta { font-size: 12px; color: var(--muted); text-align: right; }

/* Verdict Hero */
.verdict-hero {
  border-radius: var(--radius);
  padding: 20px 16px;
  text-align: center;
  margin-bottom: 16px;
}
.verdict-hero__status {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.verdict-hero__title { font-size: 20px; font-weight: 800; margin-bottom: 6px; color: var(--text); }
.verdict-hero__detail { font-size: 13px; color: var(--muted); line-height: 1.5; }

/* Verdict states */
.verdict--ok .verdict-hero { background: var(--success-bg); }
.verdict--ok .verdict-hero__status { color: var(--success); }
.verdict--warning .verdict-hero { background: var(--warning-bg); }
.verdict--warning .verdict-hero__status { color: var(--warning); }
.verdict--danger .verdict-hero { background: var(--danger-bg); }
.verdict--danger .verdict-hero__status { color: var(--danger); }

/* Delta section */
.delta-section {
  background: var(--soft);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  margin-bottom: 16px;
}
.delta-section__label { font-size: 11px; font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: 0.8px; margin-bottom: 8px; }
.delta-section__value { font-size: 56px; font-weight: 800; line-height: 1.1; color: var(--text); }
.delta-section__unit { font-size: 24px; font-weight: 500; color: var(--muted); }
.delta-section__usd { font-size: 15px; color: var(--muted); margin-top: 6px; }

/* Score bar */
.score-section { margin-bottom: 16px; }
.score-section__label { font-size: 12px; color: var(--muted); margin-bottom: 6px; }
.progress-bar { height: 8px; background: var(--soft); border-radius: 99px; overflow: hidden; }
.progress-bar__fill { height: 100%; border-radius: 99px; transition: width 0.4s ease; }
.progress-bar__fill--green { background: var(--success); }
.progress-bar__fill--orange { background: var(--warning); }
.progress-bar__fill--gray { background: var(--muted); }
.score-section__pct { font-size: 13px; font-weight: 600; margin-top: 6px; }

/* Evidence chain */
.evidence-chain {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.evidence-node {
  background: var(--panel);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  text-align: center;
  min-width: 80px;
}
.evidence-node__label { font-size: 11px; color: var(--muted); margin-bottom: 4px; }
.evidence-node__value { font-size: 15px; font-weight: 700; color: var(--text); font-family: var(--mono); }
.evidence-arrow { font-size: 18px; color: #cbd5e1; }

/* Tech grid */
.tech-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin-bottom: 16px;
}
.tech-item { display: flex; flex-direction: column; gap: 2px; padding: 10px; background: var(--soft); border-radius: var(--radius-sm); }
.tech-item__label { font-size: 11px; color: var(--muted); }
.tech-item__value { font-size: 13px; font-weight: 600; color: var(--text); word-break: break-all; font-family: var(--mono); }

/* Safety note */
.safety-note {
  background: var(--soft);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  font-size: 12px;
  color: var(--muted);
  line-height: 1.6;
  margin-bottom: 16px;
}

/* Report footer */
.report-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 14px;
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--muted);
}

/* ── Form elements ──────────────────────────────── */
.form-group { margin-bottom: 16px; }
.form-label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}
.form-label--optional::after { content: '（可选）'; font-weight: 400; color: var(--muted); margin-left: 4px; font-size: 12px; }
.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: var(--font);
  color: var(--text);
  background: var(--panel);
  transition: border-color 0.15s;
  min-height: 44px;
}
.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--info);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.12);
}
.form-input::placeholder, .form-textarea::placeholder { color: #94a3b8; }
.form-select { appearance: none; background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: right 12px center; padding-right: 36px; cursor: pointer; }
.form-textarea { resize: vertical; min-height: 80px; line-height: 1.6; }
.form-hint { font-size: 12px; color: var(--muted); margin-top: 4px; }

/* ── Section headings ──────────────────────────── */
.section { padding: 48px 0; }
.section--alt { background: var(--panel); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section__title { font-size: 22px; font-weight: 800; margin-bottom: 6px; color: var(--text); }
.section__desc { font-size: 15px; color: var(--muted); margin-bottom: 24px; line-height: 1.6; }
.section__title--center { text-align: center; }

/* ── Hero ────────────────────────────────────── */
.hero {
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  padding: 64px 0 56px;
  text-align: center;
}
.hero__badge {
  display: inline-block;
  background: var(--info-bg);
  color: var(--info);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 20px;
  margin-bottom: 16px;
  letter-spacing: 0.3px;
}
.hero__title { font-size: clamp(26px, 5vw, 40px); font-weight: 800; letter-spacing: -0.5px; margin-bottom: 12px; line-height: 1.2; }
.hero__sub { font-size: clamp(15px, 2.5vw, 17px); color: var(--muted); max-width: 520px; margin: 0 auto 28px; line-height: 1.6; }
.hero__actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* ── Feature cards ────────────────────────────── */
.feature-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.feature-card { }
.feature-card__icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 12px;
}
.feature-card__icon svg { width: 20px; height: 20px; color: #fff; }
.feature-card__icon--blue { background: var(--info); }
.feature-card__icon--green { background: var(--success); }
.feature-card__icon--orange { background: var(--warning); }
.feature-card__title { font-size: 15px; font-weight: 700; margin-bottom: 6px; }
.feature-card__desc { font-size: 13px; color: var(--muted); line-height: 1.6; }

/* ── Comparison ──────────────────────────────── */
.compare-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.compare-table th { text-align: left; padding: 10px 14px; background: var(--soft); font-weight: 600; border-bottom: 2px solid var(--border); }
.compare-table td { padding: 12px 14px; border-bottom: 1px solid var(--border); vertical-align: top; }
.compare-table tr:last-child td { border-bottom: none; }
.compare-table td:first-child { font-weight: 600; white-space: nowrap; }

/* ── Result cards ──────────────────────────── */
.result-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 12px; }
.result-card {
  border-radius: var(--radius);
  padding: 16px;
  border: 2px solid transparent;
}
.result-card__status { font-size: 10px; font-weight: 700; letter-spacing: 1px; text-transform: uppercase; margin-bottom: 8px; }
.result-card__title { font-size: 14px; font-weight: 700; margin-bottom: 6px; }
.result-card__desc { font-size: 12px; line-height: 1.5; }
.result-card--ok { background: var(--success-bg); border-color: #bbf7d0; }
.result-card--ok .result-card__status { color: var(--success); }
.result-card--warning { background: var(--warning-bg); border-color: #fde68a; }
.result-card--warning .result-card__status { color: var(--warning); }
.result-card--danger { background: var(--danger-bg); border-color: #fecaca; }
.result-card--danger .result-card__status { color: var(--danger); }

/* ── Guide page article ──────────────────── */
.article { max-width: 680px; margin: 0 auto; }
.article h2 { font-size: 20px; font-weight: 700; margin: 36px 0 12px; color: var(--text); }
.article h3 { font-size: 16px; font-weight: 700; margin: 24px 0 8px; color: var(--text); }
.article p { margin-bottom: 14px; color: #374151; line-height: 1.8; }
.article ul, .article ol { margin: 0 0 14px 20px; color: #374151; line-height: 1.8; }
.article li { margin-bottom: 6px; }
.article code {
  background: var(--soft);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 13px;
}
.article pre {
  background: #0f172a;
  color: #e2e8f0;
  padding: 16px 20px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin-bottom: 16px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.7;
}
.article pre code { background: none; padding: 0; color: inherit; }
.article blockquote {
  border-left: 4px solid var(--border);
  padding-left: 16px;
  color: var(--muted);
  margin-bottom: 14px;
}

/* ── Code block ─────────────────────────── */
.code-block {
  background: #0f172a;
  color: #e2e8f0;
  border-radius: var(--radius);
  padding: 16px 20px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.7;
  overflow-x: auto;
  margin-bottom: 16px;
  white-space: pre;
}

/* ── Alert / callout ─────────────────── */
.callout {
  background: var(--soft);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  font-size: 14px;
  color: var(--muted);
  line-height: 1.6;
  margin-bottom: 16px;
  display: flex;
  gap: 10px;
}
.callout__icon { flex-shrink: 0; width: 18px; height: 18px; margin-top: 1px; }
.callout--info { background: var(--info-bg); color: #1e40af; }
.callout--warn { background: var(--warning-bg); color: #92400e; }
.callout--danger { background: var(--danger-bg); color: #991b1b; }

/* ── Divider ─────────────────────────── */
.divider { border: none; border-top: 1px solid var(--border); margin: 40px 0; }

/* ── Action row ─────────────────────── */
.action-row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.action-row--center { justify-content: center; }

/* ── Toast ─────────────────────────── */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent);
  color: #fff;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow-md);
  z-index: 9999;
  animation: toast-in 0.2s ease-out;
}
@keyframes toast-in {
  from { opacity: 0; transform: translateX(-50%) translateY(8px); }
  to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

/* ── Mobile ─────────────────────────────────────── */
@media (max-width: 640px) {
  .site-nav { display: none; }
  .site-nav.open { display: flex; flex-direction: column; position: absolute; top: 60px; left: 0; right: 0; background: var(--panel); border-bottom: 1px solid var(--border); padding: 8px; z-index: 99; }
  .site-nav.open a { border-radius: var(--radius-sm); }
  .site-nav.open .lang-switcher { padding: 6px 12px; border-radius: var(--radius-sm); }
  .nav-toggle { display: flex; }
  .hero { padding: 48px 0 40px; }
  .hero__title { font-size: 26px; }
  .hero__actions { flex-direction: column; align-items: stretch; }
  .hero__actions .btn { width: 100%; }
  .section { padding: 36px 0; }
  .feature-grid { grid-template-columns: 1fr; }
  .result-cards { grid-template-columns: 1fr; }
  .tech-grid { grid-template-columns: 1fr; }
  .evidence-chain { gap: 6px; }
  .evidence-node { min-width: 64px; padding: 10px 12px; }
  .evidence-node__value { font-size: 13px; }
  .compare-table { font-size: 13px; }
  .action-row { flex-direction: column; }
  .action-row .btn { width: 100%; }
  .article { padding: 0 4px; }
  .article h2 { font-size: 18px; }
  .delta-section__value { font-size: 44px; }
  .billing-report-card { padding: 16px; }
}