/* Grande AI Hub — shared stylesheet.
   Used by both the Chinese homepage (/) and the North America homepage (/us/).
   Extracted from index.html's inline <style> on 2026-07-27 so the two pages
   cannot drift visually. Edit here, never re-inline. */

:root {
  --bg: #fbfbfa;
  --surface: #ffffff;
  --surface2: #f5f4f1;
  --border: #e9e8e4;
  --border2: #d9d8d2;
  --ink: #1a1a17;
  --ink2: #56554d;
  --ink3: #8d8c82;
  --accent: #ef5f3c;
  --accent-active: #d6481f;
  --accent-tint: #fdeee8;
  --teal: #0d9488;
  --teal-hover: #0f766e;
  --teal1: #14b8a6;
  --teal2: #10b981;
  --shadow-sm: 0 1px 2px rgba(20,20,15,0.05);
  --shadow-md: 0 1px 2px rgba(20,20,15,0.04), 0 3px 10px rgba(20,20,15,0.06);
  --shadow-card: 0 1px 2px rgba(20,20,15,0.04), 0 14px 44px rgba(20,20,15,0.07);
  --shadow-tile: 0 6px 16px rgba(20,20,15,0.13), 0 1px 3px rgba(20,20,15,0.08), inset 0 1px 0 rgba(255,255,255,0.07);
  --shadow-tile-hover: 0 12px 26px rgba(20,20,15,0.20), 0 1px 3px rgba(20,20,15,0.08), inset 0 1px 0 rgba(255,255,255,0.09);
  --max-width: min(94vw, 1680px);
  --font-display: "Bricolage Grotesque", "Noto Sans SC", "PingFang SC", system-ui, -apple-system, sans-serif;
  --font-sans: "Inter", "Noto Sans SC", "PingFang SC", system-ui, -apple-system, sans-serif;
  --font-serif: "Noto Serif SC", "Songti SC", Georgia, "Times New Roman", serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", ui-monospace, Menlo, Consolas, monospace;
}

@keyframes gaDot {
  0%, 100% { opacity: 0.4; transform: scale(0.85); }
  50% { opacity: 1; transform: scale(1); }
}

@keyframes gaFade { from { opacity: 0; } to { opacity: 1; } }
@keyframes gaPop {
  from { opacity: 0; transform: translateY(10px) scale(0.985); }
  to { opacity: 1; transform: none; }
}
@keyframes gaPanel {
  from { opacity: 0; transform: translateY(-6px); }
  to { opacity: 1; transform: none; }
}

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

/* 双语切换规则已删除（2026-07-27）：中英文现在是 / 和 /us/ 两个独立页面，
   不再靠 .zh/.en 同页藏显。别再加回来 —— 见 docs/多市场架构-中文站与北美站.md 第 9 节。 */

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--ink); text-decoration: none; }

/* ── Header ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(251, 251, 250, 0.85);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.85rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  text-decoration: none;
  color: var(--ink);
  flex: none;
}

.brand-logo {
  width: 36px;
  height: 36px;
  background: var(--surface);
  object-fit: contain;
  display: block;
  box-shadow: 0 1px 3px rgba(20, 20, 15, 0.08);
  flex: none;
}

.brand-name {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: 0.02em;
  line-height: 1.1;
}

.brand-dot {
  width: 7px;
  height: 7px;
  background: var(--teal);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.13);
  animation: gaDot 1.8s ease-in-out infinite;
  flex: none;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Icon-only social buttons */
.icon-btn {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  cursor: pointer;
  text-decoration: none;
  overflow: hidden;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.icon-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(20, 20, 15, 0.12);
}

.icon-btn:active { transform: scale(0.95); }

.icon-btn img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
}

.header-sep {
  width: 1px;
  height: 22px;
  background: var(--border2);
  margin: 0 4px;
}

/* Compact 中 / EN lang toggle */
.lang-toggle {
  display: inline-flex;
  align-items: stretch;
  height: 36px;
  background: var(--surface2);
  border: 1px solid var(--border);
  padding: 3px;
  gap: 0;
}

.lang-button {
  padding: 0 11px;
  display: flex;
  align-items: center;
  border: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 500;
  color: var(--ink3);
  cursor: pointer;
  transition: color 0.15s ease;
}

.lang-button:not([aria-pressed="true"]):hover {
  color: var(--accent);
}

.lang-button[aria-pressed="true"] {
  background: var(--surface);
  color: var(--ink);
  font-weight: 600;
  box-shadow: 0 1px 2px rgba(20, 20, 15, 0.10);
}

/* Filled teal Contact CTA */
.contact-btn {
  height: 36px;
  padding: 0 18px;
  display: inline-flex;
  align-items: center;
  border: 1px solid transparent;
  background: var(--teal);
  color: #fff;
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 1px 2px rgba(13, 148, 136, 0.18);
  transition: background 0.16s ease, color 0.16s ease, border-color 0.16s ease, transform 0.16s ease, box-shadow 0.16s ease;
}

.contact-btn:hover {
  background: var(--surface);
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: none;
  transform: translateY(-2px);
}

.contact-btn:active { transform: scale(0.96); }

/* ── Contact Modal ── */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(24, 23, 20, 0.42);
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
  z-index: 100;
  align-items: center;
  justify-content: center;
  animation: gaFade 0.18s ease;
}

.modal-overlay.active { display: flex; }

.modal-box {
  width: 440px;
  max-width: 92%;
  background: var(--surface);
  border: 1px solid var(--border2);
  box-shadow: 0 30px 80px rgba(20, 20, 15, 0.32);
  position: relative;
  text-align: left;
  animation: gaPop 0.22s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  border-bottom: 1px solid var(--border);
}

.modal-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 18px;
  color: var(--ink);
}

.modal-close {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border: 1px solid transparent;
  background: transparent;
  cursor: pointer;
  color: var(--ink3);
  font-size: 16px;
  line-height: 1;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.modal-close:hover {
  border-color: var(--border2);
  color: var(--ink);
}

.modal-body { padding: 24px 22px; }

.modal-intro {
  display: flex;
  align-items: center;
  gap: 16px;
}

.modal-avatar {
  width: 62px;
  height: 62px;
  object-fit: cover;
  flex: none;
  background: var(--teal);
  box-shadow: 0 2px 8px rgba(13, 148, 136, 0.20);
}

.modal-intro-name {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.2;
}

.modal-intro-role {
  margin-top: 4px;
  font-size: 13px;
  color: var(--ink2);
}

.modal-bio {
  margin-top: 18px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink2);
}

.modal-contact-grid {
  margin-top: 22px;
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

.modal-qr-block {
  flex: none;
  text-align: center;
}

.modal-qr {
  width: 180px;
  height: 180px;
  padding: 8px;
  background: #fff;
  border: 1px solid var(--border2);
  object-fit: contain;
  display: block;
}

.modal-qr-label {
  margin-top: 8px;
  font-size: 12px;
  color: var(--ink3);
}

.modal-email-block {
  flex: 1;
  padding-top: 2px;
}

.modal-email-label {
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink3);
  font-weight: 600;
}

.modal-email {
  display: inline-block;
  margin-top: 6px;
  font-family: var(--font-sans);
  font-size: 14px;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--accent);
  padding-bottom: 2px;
}

.modal-email:hover { color: var(--accent-active); }

.modal-scan-hint {
  margin-top: 16px;
  font-size: 12px;
  color: var(--ink3);
  line-height: 1.6;
}

.modal-social {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  display: flex;
  gap: 14px;
  align-items: center;
}

.modal-social-logo {
  width: 54px;
  height: 54px;
  border-radius: 50%;
  object-fit: cover;
  flex: none;
  background: #000;
}

.modal-social-text { flex: 1; min-width: 0; }

.modal-social-label {
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink3);
  font-weight: 600;
}

.modal-social-name {
  margin-top: 4px;
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
}

.modal-social-platforms {
  margin-top: 4px;
  font-size: 12px;
  color: var(--ink2);
  line-height: 1.55;
}

/* ── Promo Slogan Band (with image carousel) ── */
.slogan-band {
  position: relative;
  width: 100%;
  min-height: 360px;
  padding: 5rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  isolation: isolate;
}

.slogan-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  opacity: 0;
  transition: opacity 1.2s ease;
  z-index: 0;
}

.slogan-bg.is-active { opacity: 1; }

.slogan-band::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.10) 0%, rgba(0,0,0,0.30) 100%);
  z-index: 1;
  pointer-events: none;
}

.slogan-inner {
  position: relative;
  z-index: 2;
  max-width: var(--max-width);
  margin: 0 auto;
}

.slogan-bar {
  width: 32px;
  height: 2px;
  background: #ffffff;
  margin: 0 auto 1.4rem;
  box-shadow: 0 1px 2px rgba(0,0,0,0.15);
}

.slogan-zh {
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 1.7rem;
  line-height: 1.4;
  color: #ffffff;
  letter-spacing: 0.04em;
  text-shadow: 0 2px 14px rgba(0,0,0,0.30);
}

.slogan-en {
  margin-top: 0.9rem;
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 1.05rem;
  color: rgba(255,255,255,0.92);
  letter-spacing: 0.04em;
  text-shadow: 0 1px 8px rgba(0,0,0,0.25);
}

.slogan-dots {
  position: absolute;
  bottom: 1.25rem;
  left: 0;
  right: 0;
  display: flex;
  justify-content: center;
  gap: 8px;
  z-index: 3;
}

.slogan-dot {
  width: 7px;
  height: 7px;
  border: none;
  padding: 0;
  border-radius: 50%;
  background: rgba(255,255,255,0.45);
  cursor: pointer;
  transition: background 0.25s ease, transform 0.25s ease;
}

.slogan-dot.is-active {
  background: #ffffff;
  transform: scale(1.35);
}

/* ── Page ── */
.page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.25rem 1rem 1.5rem;
}

/* ── Page Layout ── */

/* ── Card ── */
.card {
  background: var(--surface);
  box-shadow: var(--shadow-card);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
}

.card-header {
  margin-bottom: 1rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--border);
}

.section-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--ink);
  letter-spacing: 0.03em;
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
}

.section-title::before {
  content: "";
  width: 3px;
  height: 17px;
  background: var(--accent);
  display: inline-block;
  align-self: center;
}

.section-count {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--ink3);
  letter-spacing: 0.08em;
  font-variant-numeric: tabular-nums;
  margin-left: 0.25rem;
}

/* ── Article Feed ── */
.article-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-top: 1.4rem;
}

.article-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 2px solid transparent;
  box-shadow: var(--shadow-sm);
  display: block;
  text-decoration: none;
  color: var(--ink);
  transition: transform 0.16s ease, box-shadow 0.16s ease, border-color 0.16s ease;
}

.article-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-left-color: var(--accent);
}

.article-inner {
  padding: 22px 28px 20px;
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 12px;
}

.article-tag {
  padding: 3px 10px;
  border: 1px solid var(--border2);
  font-size: 12px;
  color: var(--ink2);
  letter-spacing: 0.03em;
}

.article-date {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink3);
  letter-spacing: 0.06em;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.article-card h3 {
  font-family: var(--font-serif);
  font-size: 14px;
  font-weight: 600;
  line-height: 1.6;
  letter-spacing: 0.02em;
  margin: 0;
  color: var(--ink);
}

.article-excerpt {
  margin-top: 11px;
  font-size: 14px;
  color: var(--ink2);
  line-height: 1.7;
  max-width: 760px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.article-read-more {
  display: inline-block;
  margin-top: 16px;
  font-size: 13px;
  color: var(--ink2);
  border-bottom: 1px solid var(--border2);
  padding-bottom: 3px;
  letter-spacing: 0.02em;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.article-card:hover .article-read-more {
  color: var(--accent);
  border-color: var(--accent);
}

/* ── Promo strip (免费额度 / 企业合作) ── */
.promo-strip {
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; flex-wrap: wrap;
  background: linear-gradient(135deg, rgba(13,148,136,0.10), rgba(13,148,136,0.03));
  border: 1px solid rgba(13,148,136,0.24);
  border-radius: 14px; padding: 18px 24px; margin-top: 1.5rem;
}
.promo-offers { display: flex; align-items: center; gap: 32px; flex-wrap: wrap; flex: 1; min-width: 0; }
.promo-offer { display: flex; align-items: center; gap: 12px; }
.promo-badge {
  font-family: var(--font-display); font-size: 26px; font-weight: 700;
  color: var(--teal); line-height: 1; flex-shrink: 0; letter-spacing: -0.02em;
}
.promo-copy { display: flex; flex-direction: column; gap: 1px; min-width: 0; }
.promo-copy strong { font-size: 14px; font-weight: 600; color: var(--ink); }
.promo-copy em { font-size: 12px; font-style: normal; color: var(--ink3); }
.promo-cta { display: flex; gap: 10px; flex-wrap: wrap; flex-shrink: 0; }
.promo-btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 9px 18px; border-radius: 8px; font-family: var(--font-sans);
  font-size: 13.5px; font-weight: 500; text-decoration: none; cursor: pointer;
  border: 1px solid var(--teal); color: var(--teal); background: transparent;
  transition: background 0.18s ease, color 0.18s ease, box-shadow 0.18s ease;
  white-space: nowrap;
}
.promo-btn:hover { background: rgba(13,148,136,0.10); }
.promo-btn.primary { background: var(--teal); color: #fff; box-shadow: 0 4px 12px rgba(13,148,136,0.26); }
.promo-btn.primary:hover { background: var(--teal-hover); }
@media (max-width: 720px) {
  .promo-strip { flex-direction: column; align-items: stretch; gap: 16px; padding: 16px 18px; }
  .promo-offers { gap: 16px; flex-direction: column; align-items: flex-start; }
  .promo-cta { justify-content: stretch; }
  .promo-btn { flex: 1; }
}

/* ── Tool Tiles (Ink Studio) ── */
.tools-zone {
  position: relative;
  margin-top: 1.5rem;
}

.tool-cards {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 6px;
  margin: 0;
  padding: 0;
}

.tool-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.75rem;
  padding: 14px 4px 12px;
  text-decoration: none;
  color: var(--ink);
  background: transparent;
  box-shadow: none;
  transition: transform 0.18s ease;
}

.tool-card:hover {
  transform: translateY(-5px);
}

.tool-card:active { transform: translateY(-1px) scale(0.95); }

.tool-card-icon {
  width: 104px;
  height: 104px;
  background: linear-gradient(155deg, #26261f, #141411);
  display: grid;
  place-items: center;
  color: #fff;
  box-shadow: var(--shadow-tile);
  overflow: hidden;
  transition: transform 0.22s cubic-bezier(0.2, 0.7, 0.3, 1), box-shadow 0.22s ease;
}

.tool-card:hover .tool-card-icon {
  transform: translateY(-4px);
  box-shadow: var(--shadow-tile-hover);
}

.tool-card-icon svg {
  width: 42px;
  height: 42px;
  stroke: #fff;
  fill: none;
  stroke-width: 1.6;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.tool-card-icon { position: relative; }

.tool-card-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.tool-card-icon .icon-default,
.tool-card-icon .icon-hover {
  position: absolute;
  inset: 0;
  transition: opacity 0.18s ease;
}

.tool-card-icon .icon-hover { opacity: 0; }
.tool-card:hover .tool-card-icon .icon-default,
.tool-card.is-active .tool-card-icon .icon-default { opacity: 0; }
.tool-card:hover .tool-card-icon .icon-hover,
.tool-card.is-active .tool-card-icon .icon-hover { opacity: 1; }

.tool-card h3 {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.35;
  color: var(--ink2);
  margin: 0;
  max-width: 100%;
  word-break: break-word;
  transition: color 0.18s ease;
}

.tool-card:hover h3 { color: var(--ink); }

/* Hover info panel */
.tool-info-panel {
  position: relative;
  margin-top: 16px;
  padding: 22px 26px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 2px solid var(--accent);
  box-shadow: var(--shadow-md);
  display: none;
  align-items: center;
  justify-content: space-between;
  gap: 26px;
  animation: gaPanel 0.24s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.tools-zone.is-hover .tool-info-panel { display: flex; }

.tool-info-panel::before,
.tool-info-panel::after {
  content: "";
  position: absolute;
  top: -9px;
  transform: translateX(-50%);
  left: var(--bloom-x, 50%);
  width: 0;
  height: 0;
  border-left: 9px solid transparent;
  border-right: 9px solid transparent;
  border-bottom: 9px solid var(--accent);
  transition: left 0.18s ease;
}
.tool-info-panel::after {
  top: -7px;
  border-left-width: 8px;
  border-right-width: 8px;
  border-bottom: 8px solid var(--surface);
}

.tool-info-example {
  flex: none;
  width: 340px;
  max-width: 44%;
  border-radius: 8px;
  border: 1px solid var(--border);
  object-fit: cover;
  display: none;
}
.tool-info-panel.has-example .tool-info-example { display: block; }

.tool-info-body { flex: 1; min-width: 0; }

.tool-info-title {
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--ink);
}

.tool-info-title::before {
  content: "";
  width: 7px;
  height: 7px;
  background: var(--teal);
  display: inline-block;
}

.tool-info-value {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-top: 10px; font-size: 13px; color: var(--ink2);
}
.tool-info-value[hidden] { display: none; }
.tiv-cost {
  flex-shrink: 0; font-weight: 700; color: var(--teal); font-size: 13px;
  background: rgba(13,148,136,0.10); padding: 3px 11px; border-radius: 999px;
  white-space: nowrap;
}
.tiv-text { color: var(--ink2); }

.tool-info-desc {
  margin-top: 8px;
  font-size: 0.875rem;
  line-height: 1.65;
  color: var(--ink2);
  max-width: 720px;
}

.tool-info-cta {
  flex: none;
  display: inline-flex;
  align-items: center;
  padding: 9px 16px;
  background: var(--teal);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-decoration: none;
  white-space: nowrap;
  box-shadow: 0 1px 2px rgba(13, 148, 136, 0.18);
  transition: filter 0.15s ease, transform 0.15s ease;
}

.tool-info-cta:hover {
  filter: brightness(1.05);
  transform: translateY(-1px);
  color: #fff;
}

/* ── Feature Card ── */
.feature-stack {
  margin-top: 1.4rem;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.feature-stack .feature-card {
  margin-top: 0;
}

.feature-card {
  margin-top: 1.4rem;
  display: flex;
  align-items: center;
  gap: 28px;
  padding: 28px 32px;
  background: var(--surface);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  text-decoration: none;
  color: var(--ink);
  transition: transform 0.16s ease, box-shadow 0.16s ease, border-color 0.16s ease;
}

.feature-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.feature-card-icon {
  width: 80px;
  height: 80px;
  flex: none;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.feature-card-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.feature-card-body { flex: 1; min-width: 0; }

.feature-card-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.4;
}

.feature-card-desc {
  margin-top: 8px;
  font-size: 14px;
  color: var(--ink2);
  line-height: 1.65;
}

.feature-card-meta {
  margin-top: 12px;
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink3);
  letter-spacing: 0.03em;
}

.feature-card-meta span::before {
  content: "•";
  margin-right: 6px;
  color: var(--accent);
}

.feature-card-cta {
  flex: none;
  display: inline-flex;
  align-items: center;
  padding: 10px 18px;
  background: var(--teal);
  color: #fff;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.02em;
  border-radius: 8px;
  box-shadow: 0 1px 2px rgba(13, 148, 136, 0.18);
  transition: filter 0.15s ease, transform 0.15s ease;
}

.feature-card:hover .feature-card-cta {
  filter: brightness(1.05);
  transform: translateX(2px);
}

@media (max-width: 720px) {
  .feature-card {
    flex-direction: column;
    align-items: flex-start;
    text-align: left;
    padding: 22px;
  }
  .feature-card-cta { align-self: stretch; justify-content: center; }
}

/* ── Hot Topics ── */
.hot-tabs {
  margin-top: 1.4rem;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.hot-tab {
  padding: 6px 14px;
  border: 1px solid var(--border2);
  background: var(--surface);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  color: var(--ink2);
  cursor: pointer;
  border-radius: 8px;
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease;
}

.hot-tab:hover { border-color: var(--accent); color: var(--accent); }

.hot-tab.is-active {
  background: var(--ink);
  border-color: var(--ink);
  color: #fff;
}

.hot-list {
  margin-top: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.hot-item {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 11px 18px;
  text-decoration: none;
  color: var(--ink);
  border-bottom: 1px solid var(--border);
  transition: background 0.12s ease;
}

.hot-item:last-child { border-bottom: none; }
.hot-item:hover { background: var(--surface2); }

.hot-rank {
  flex: none;
  width: 22px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--ink3);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.hot-item:nth-child(-n+3) .hot-rank { color: var(--accent); }

.hot-title {
  flex: 1;
  min-width: 0;
  font-size: 14px;
  line-height: 1.55;
  color: var(--ink);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.hot-item:hover .hot-title { color: var(--accent-active); }

.hot-value {
  flex: none;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink3);
  white-space: nowrap;
}

.hot-empty {
  padding: 2rem;
  text-align: center;
  font-size: 0.8rem;
  color: var(--ink3);
}

@media (max-width: 640px) {
  .hot-value { display: none; }
  .hot-item { padding: 11px 14px; }
}

/* ── Page TOC (left directory) ── */
.page-with-toc {
  display: grid;
  grid-template-columns: 170px minmax(0, 1fr);
  gap: 48px;
  align-items: start;
}

.page-toc {
  position: sticky;
  top: 92px;
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding-top: 0.35rem;
}

.toc-link {
  padding: 10px 12px 10px 16px;
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 500;
  color: var(--ink2);
  text-decoration: none;
  border-left: 2px solid var(--border);
  transition: color 0.15s ease, border-color 0.15s ease;
}

.toc-link:hover { color: var(--ink); }

.toc-link.is-active {
  color: var(--ink);
  font-weight: 600;
  border-left-color: var(--accent);
}

.page-section {
  scroll-margin-top: 90px;
}

.page-section + .page-section {
  margin-top: 3rem;
}

@media (max-width: 899px) {
  .page-with-toc { display: block; }
  .page-toc { display: none; }
}

/* ── Section Divider ── */
.section-divider {
  margin-bottom: 1.25rem;
}

.section-divider .section-title {
  padding-bottom: 0.6rem;
}

/* ── Footer ── */
.site-footer {
  margin-top: 3rem;
  border-top: 1px solid var(--border);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.6rem 1.5rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  font-size: 12px;
  color: var(--ink3);
  letter-spacing: 0.02em;
}

.footer-wordmark {
  font-family: var(--font-display);
  font-weight: 500;
  color: var(--ink3);
  letter-spacing: 0.03em;
}

@media (max-width: 640px) {
  .footer-inner { flex-direction: column; align-items: flex-start; gap: 0.4rem; text-align: left; }
}

/* ── Auth badge ── */
.auth-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 14px 4px 5px;
  border: 1px solid var(--border2);
  border-radius: 999px;
  background: var(--surface);
  font-size: 0.8rem;
  color: var(--ink);
  text-decoration: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.auth-badge:hover {
  border-color: var(--teal);
  box-shadow: 0 1px 2px rgba(20, 20, 15, 0.05);
}

.auth-avatar {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--teal);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 600;
  flex-shrink: 0;
}

.auth-nickname {
  font-weight: 500;
  color: var(--ink);
}

.auth-credits {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--teal);
  font-weight: 600;
}

.auth-login-btn {
  display: inline-flex;
  align-items: center;
  height: 36px;
  padding: 0 15px;
  border: 1px solid var(--border2);
  background: var(--surface);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  color: var(--ink2);
  cursor: pointer;
  text-decoration: none;
  transition: border-color 0.15s ease, color 0.15s ease, transform 0.15s ease;
}

.auth-login-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

/* ── Rounded Corners ── */
.brand-logo,
.icon-btn,
.lang-toggle,
.contact-btn,
.auth-login-btn { border-radius: 8px; }

.lang-button { border-radius: 6px; }
.modal-close { border-radius: 6px; }

.tool-card-icon { border-radius: 20px; }

.article-card,
.tool-info-panel,
.card { border-radius: 12px; }

.modal-box { border-radius: 14px; }
.modal-avatar,
.modal-qr { border-radius: 10px; }

.article-tag,
.tool-info-cta,
.section-count { border-radius: 4px; }

/* ── Responsive: Desktop ── */
@media (min-width: 768px) {
  .page { padding: 2rem 1.5rem; }
  .article-inner { padding: 1.75rem; }
}

/* ── Responsive: Mobile ── */
@media (max-width: 767px) {
  .header-inner { padding: 0.7rem 1rem; gap: 0.5rem; }
  .header-sep { display: none; }
  .contact-btn { padding: 0 12px; font-size: 12px; }
  .auth-login-btn { display: none; }
  .tool-info-panel { flex-direction: column; align-items: stretch; }
  .tool-info-example { width: 100%; max-width: 100%; }
  .tool-info-cta { align-self: flex-start; }
}

/* ── /us/ 专用：工具区空状态 ─────────────────────────────────
   北美站还没挂工具时的占位。第一张工具卡片上线后即可连同
   us/index.html 里的 .tools-empty 一起删掉。 */
.tools-empty {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 2rem 1.75rem;
  border: 1px dashed var(--border2);
  border-radius: 12px;
  background: var(--surface2);
}
.tools-empty strong {
  font-size: 1rem;
  color: var(--ink);
}
.tools-empty span {
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--ink2);
  max-width: 46ch;
}
.tools-empty .promo-btn { margin-top: 0.25rem; }

/* ── 地域软引导条（只在中文首页，北美 IP 才显示）───────────────
   刻意做成「提示 + 手动点」而不是自动跳转，理由见
   docs/多市场架构-中文站与北美站.md 第 2.2 节。 */
.geo-hint {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem 0.85rem;
  padding: 0.6rem 2.5rem 0.6rem 1rem;
  position: relative;
  background: var(--ink);
  color: #fff;
  font-size: 0.82rem;
  line-height: 1.4;
}
.geo-hint[hidden] { display: none; }
.geo-hint-text { opacity: 0.82; }
.geo-hint-go {
  color: #fff;
  font-weight: 600;
  border-bottom: 1px solid rgba(255, 255, 255, 0.45);
  padding-bottom: 1px;
}
.geo-hint-go:hover { border-bottom-color: #fff; }
.geo-hint-close {
  position: absolute;
  right: 0.6rem;
  top: 50%;
  transform: translateY(-50%);
  width: 1.6rem;
  height: 1.6rem;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: #fff;
  opacity: 0.6;
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
}
.geo-hint-close:hover { opacity: 1; background: rgba(255, 255, 255, 0.12); }