:root {
  color-scheme: light dark;
  --tap-size: 48px;
  --container: 1120px;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;

  --shadow-1: 0 1px 3px rgba(13, 8, 38, 0.08), 0 1px 2px rgba(13, 8, 38, 0.04);
  --shadow-2: 0 12px 40px rgba(13, 8, 38, 0.12);

  /* Neutrals: Modern OKLCH (Tinted) */
  --bg: oklch(98% 0.004 285);
  --surface: oklch(100% 0 0);
  --surface-2: oklch(96% 0.008 285);
  --text: oklch(25% 0.02 285);
  --muted: oklch(50% 0.03 285);
  --border: oklch(25% 0.02 285 / 0.12);

  /* Categories (OKLCH Perception Uniform) */
  --p-primary: 285; /* Indigo/Brand */
  --p-efficiency: 142; /* FloatCalc Green */
  --p-interaction: 245; /* AirSwipe Sky Blue */
  --p-privacy: 160; /* Green/Emerald */

  --bg-tint: oklch(98% 0.005 var(--p-interaction));
  
  --color-primary: oklch(52% 0.16 var(--p-primary));
  --color-efficiency: oklch(65% 0.18 var(--p-efficiency));
  --color-interaction: oklch(58% 0.18 var(--p-interaction));
  --color-privacy: oklch(65% 0.14 var(--p-privacy));

  --primary: var(--color-primary);
  --primary-ink: oklch(35% 0.18 var(--p-primary));
  --primary-contrast: oklch(100% 0 0);
  --accent: oklch(65% 0.18 310);
  --accent-2: oklch(68% 0.16 170);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-tint: oklch(14% 0.01 var(--p-interaction));
    
    --bg: oklch(12% 0.02 285);
    --surface: oklch(18% 0.04 285);
    --surface-2: oklch(22% 0.04 285);
    --text: oklch(92% 0.01 285);
    --muted: oklch(75% 0.03 285);
    --border: oklch(92% 0.01 285 / 0.12);

    --color-primary: oklch(72% 0.14 var(--p-primary));
    --color-efficiency: oklch(74% 0.14 var(--p-efficiency));
    --color-interaction: oklch(78% 0.14 var(--p-interaction));
    --color-privacy: oklch(80% 0.12 var(--p-privacy));

    --primary: var(--color-primary);
    --primary-ink: oklch(90% 0.06 var(--p-primary));
    --primary-contrast: oklch(12% 0.02 285);
    --accent: oklch(80% 0.1 310);
    --accent-2: oklch(82% 0.1 170);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  line-height: 1.6;
  /* 基础背景色：根据主题 tint 过渡 */
  background-color: var(--bg);

  --noise: url("data:image/svg+xml,%3Csvg viewBox='0 0 400 400' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
  
  background-image:
          var(--noise),
          radial-gradient(120vw 120vh at 0% 0%, color-mix(in oklch, var(--color-interaction), transparent 96%) 0%, transparent 100%),
          radial-gradient(120vw 120vh at 100% 100%, color-mix(in oklch, var(--color-efficiency), transparent 96%) 0%, transparent 100%),
          radial-gradient(circle at 50% 50%, transparent 50%, color-mix(in oklch, var(--bg-tint), transparent 94%) 100%);

  background-attachment: fixed;
  background-size: auto, 100% 100%, 100% 100%, 100% 100%;
  background-repeat: repeat, no-repeat, no-repeat, no-repeat;
  background-blend-mode: soft-light, normal, normal, normal;
  
  /* 为固定在底部的页脚预留空间，确保内容不被遮挡 */
  /* 页脚在移动端或换行时高度会增加，预留 130px 较为安全 */
  padding-bottom: 130px;
}

a {
  color: var(--primary);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.2em;
}

a:hover {
  text-decoration-thickness: 0.12em;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    "Courier New", monospace;
  font-size: 0.95em;
  padding: 0.08em 0.35em;
  border-radius: 0.5em;
  border: 1px solid var(--border);
  background: rgba(111, 59, 245, 0.1);
  color: var(--text);
}

.container {
  width: min(var(--container), calc(100% - 2rem));
  margin: 0 auto;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0.75rem;
  z-index: 1000;
  padding: 0.75rem 1rem;
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow-2);
  border: 1px solid var(--border);
}

.skip-link:focus {
  left: 0.75rem;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: saturate(1.4) blur(10px);
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  border-bottom: 1px solid var(--border);
}

@supports not (background: color-mix(in srgb, white 50%, black)) {
  .topbar {
    background: rgba(247, 248, 251, 0.8);
  }
}

@media (prefers-color-scheme: dark) {
  @supports not (background: color-mix(in srgb, white 50%, black)) {
    .topbar {
      background: rgba(11, 16, 32, 0.78);
    }
  }
}

.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.6rem 0;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  min-height: var(--tap-size);
  padding: 0.25rem 0.5rem;
  border-radius: 999px;
  text-decoration: none;
  color: var(--text);
}

.brand:hover {
  background: rgba(111, 59, 245, 0.12);
}

.brand-name {
  font-weight: 800;
  letter-spacing: 0.2px;
}

.brand-product {
  font-weight: 650;
  color: var(--muted);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-ghost:hover {
  background: rgba(111, 59, 245, 0.12);
}

.btn-ghost:active {
  transform: translateY(1px);
}

[data-lang-toggle] {
  opacity: 0;
  pointer-events: none;
  transition: opacity 120ms ease;
}

[data-lang-toggle][data-lang-ready="1"] {
  opacity: 1;
  pointer-events: auto;
}

.hero {
  padding: 1.2rem 0 1.6rem;
}

.hero-card {
  --hero-theme: var(--page-theme, var(--primary));
  background: 
    linear-gradient(
      135deg, 
      color-mix(in oklch, var(--hero-theme), transparent 92%), 
      color-mix(in oklch, var(--hero-theme), transparent 95%)
    ),
    var(--surface);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.4rem;
  box-shadow: var(--shadow-2);
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 1.2rem;
}


.hero-content {
  flex: 1;
  min-width: 0;
}



.hero-image {
  flex: 0 0 auto;
}

.hero-image img {
  width: 160px;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
}

@media (min-width: 768px) {
  .hero-image img {
    width: 200px;
  }
}

.visual-features {
  padding: 1.2rem 0;
}

.visual-features-grid {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.visual-feature-item {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.2rem;
  box-shadow: var(--shadow-1);
  overflow: hidden;
}

.visual-feature-item.reverse {
  flex-direction: row-reverse;
}

.visual-feature-content {
  flex: 1;
  min-width: 0;
}

.visual-feature-content h3 {
  margin: 0 0 0.4rem;
  font-size: 1.1rem;
  font-weight: 750;
  line-height: 1.3;
}

.visual-feature-content p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
  line-height: 1.5;
}

.visual-feature-image {
  flex: 0 0 auto;
  width: 220px;
}

.visual-feature-image img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
  display: block;
}

@media (min-width: 480px) {
  .visual-feature-content h3 {
    font-size: 1.25rem;
  }
  .visual-feature-content p {
    font-size: 1rem;
  }
}

@media (min-width: 768px) {
  .visual-feature-item {
    gap: 2rem;
    padding: 2rem;
  }
}

.eyebrow {
  color: var(--muted);
  font-weight: 650;
}

.hero h1 {
  margin: 0;
  font-size: 1.6rem;
  line-height: 1.2;
}

.hero-subtitle {
  margin: 0.5rem 0;
  font-size: clamp(1.05rem, 2.9vw, 1.35rem);
  font-weight: 600;
  color: var(--muted);
}

.btn-group {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 1rem;
}

@media (min-width: 480px) {
  .btn-group {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
  }
}

.download-wrap {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  align-items: flex-start;
}

.download-version {
  margin: 0;
  font-size: 0.82rem;
  color: var(--muted);
  opacity: 0.85;
  padding-left: 0.4rem;
  font-weight: 500;
}


.hero-meta {
  margin-top: 0.5rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.section {
  padding: 2.2rem 0;
}

.section.alt {
  background: linear-gradient(180deg, transparent, rgba(111, 59, 245, 0.08) 40%, transparent);
}

.section h2 {
  margin: 0 0 1rem;
  font-size: 1.35rem;
  letter-spacing: 0.2px;
}



.cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.9rem;
}

@media (min-width: 820px) {
  .cards.cards-3 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.principles-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
  align-items: start;
}

.principle-card {
  padding: 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-1);
}

.principle-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.2rem;
  color: var(--card-theme, var(--primary));
}

.card-variant-1 {
  --card-theme: var(--color-efficiency);
}

.card-variant-2 {
  --card-theme: var(--color-interaction);
}

.card-variant-3 {
  --card-theme: var(--color-privacy);
}

.principle-card {
  border-left: 4px solid var(--card-theme);
}

.principle-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

@media (min-width: 768px) {
  .principles-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .principle-card {
    display: flex;
    flex-direction: column;
    height: 100%;
  }
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.1rem 1rem;
  box-shadow: var(--shadow-1);
}

.card h3 {
  margin: 0 0 0.35rem;
  font-size: 1.05rem;
}

.card p {
  margin: 0;
  color: var(--muted);
}

.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 0.9rem;
}

.product-card {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
}

.product-card-eyebrow {
  margin: 0;
}

.product-card {
  --theme: var(--color-primary);
  --theme-bg: color-mix(in oklch, var(--theme), transparent 97%);
  --theme-border: color-mix(in oklch, var(--theme), transparent 88%);
  
  background: var(--theme-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--theme-border);
  transition: transform 140ms ease, box-shadow 140ms ease, border-color 140ms ease;
  overflow: hidden;
  position: relative;
}

.product-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--theme);
  opacity: 0.8;
}

.product-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 40px color-mix(in oklch, var(--theme), transparent 85%);
  border-color: var(--theme);
}

.product-card.item-efficiency {
  --theme: var(--color-efficiency);
}

.product-card.item-interaction {
  --theme: var(--color-interaction);
}

.product-card .btn-primary {
  background: var(--theme);
}

.product-card .eyebrow {
  color: var(--theme);
  font-weight: 750;
  letter-spacing: 0.5px;
}

.product-card-summary {
  font-size: 0.95rem;
  color: oklch(from var(--text) l c h / 0.85);
}

.product-card-link {
  color: var(--theme);
  text-decoration: none;
  font-weight: 800;
  transition: color 140ms ease;
}

.product-card-link:hover {
  text-decoration: underline;
  text-decoration-thickness: 1.5px;
  text-underline-offset: 3px;
}

.product-card-image {
  margin-top: 0.5rem;
  display: flex;
  justify-content: center;
  align-items: center;
}

.product-card-image img {
  border-radius: var(--radius-lg);
  filter: drop-shadow(0 8px 16px color-mix(in oklch, var(--theme), transparent 75%));
}

.hero-placeholder {
  width: min(320px, 100%);
  min-height: 220px;
  display: grid;
  align-content: center;
  justify-items: start;
  gap: 0.8rem;
  padding: 1.2rem;
  border-radius: var(--radius-md);
  border: 1px dashed var(--border);
  background:
    linear-gradient(135deg, rgba(111, 59, 245, 0.12), rgba(63, 209, 201, 0.08)),
    color-mix(in srgb, var(--surface) 84%, transparent);
  box-shadow: var(--shadow-1);
}

.hero-placeholder-title,
.hero-placeholder-copy {
  margin: 0;
}

.hero-placeholder-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text);
}

.hero-placeholder-copy {
  color: var(--muted);
}

.split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

@media (min-width: 900px) {
  .split {
    grid-template-columns: 1.2fr 0.8fr;
    align-items: start;
  }
}

.list {
  margin: 0.75rem 0 0;
  padding-left: 1.2rem;
  color: var(--muted);
}

.callout {
  margin: 1rem 0 0;
  color: var(--muted);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--tap-size);
  padding: 0.4rem 1rem;
  border-radius: var(--radius-lg);
  font-weight: 750;
  text-decoration: none;
  letter-spacing: 0.2px;
  transition: transform 120ms ease, filter 120ms ease, background 120ms ease;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn:focus-visible {
  outline: 3px solid rgba(111, 59, 245, 0.45);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--primary);
  color: var(--primary-contrast);
  box-shadow: var(--shadow-1);
}

.btn-primary:hover {
  filter: brightness(0.98);
  box-shadow: 0 10px 24px color-mix(in srgb, currentColor, transparent 75%);
}

.btn-primary:active {
  transform: translateY(1px);
}

.seo p {
  margin: 0;
  color: var(--muted);
}

.content {
  padding: 1rem 0 2.2rem;
}

.doc {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.2rem;
  box-shadow: var(--shadow-1);
}

/* Product Page Themes */
.product-page-efficiency {
  --page-theme: var(--color-efficiency);
}

.product-page-interaction {
  --page-theme: var(--color-interaction);
}

.product-page .eyebrow {
  color: var(--page-theme);
  font-weight: 750;
}

.product-page .btn-primary {
  background: var(--page-theme);
}

.doc h1 {
  margin: 0;
  font-size: 1.6rem;
}

.doc > p {
  margin: 0.6rem 0 1.1rem;
  color: var(--muted);
}

.doc h3 {
  margin: 1.2rem 0 0.4rem;
  font-size: 1.05rem;
}

.doc ul,
.doc ol {
  margin: 0.4rem 0 0;
  padding-left: 1.2rem;
  color: var(--muted);
}

.doc li + li {
  margin-top: 0.35rem;
}

.footer {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  border-top: 1px solid var(--border);
  padding: 1.25rem 0;
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
}

@supports not (background: color-mix(in srgb, white 50%, black)) {
  .footer {
    background: rgba(247, 248, 251, 0.7);
  }
}

@media (prefers-color-scheme: dark) {
  @supports not (background: color-mix(in srgb, white 50%, black)) {
    .footer {
      background: rgba(11, 16, 32, 0.7);
    }
  }
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.footer p {
  margin: 0;
  color: var(--muted);
}

.footer-links {
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: var(--tap-size);
  padding: 0 0.55rem;
  color: var(--muted);
  text-decoration: none;
  border-radius: 999px;
}

.footer-links a:hover {
  color: var(--text);
  text-decoration: none;
  background: rgba(111, 59, 245, 0.12);
}

.footer-links a:focus-visible {
  outline: 3px solid rgba(111, 59, 245, 0.45);
  outline-offset: 2px;
  color: var(--text);
  text-decoration: none;
  background: rgba(111, 59, 245, 0.12);
}

@media (prefers-reduced-motion: reduce) {
  .btn,
  .hero-chip {
    transition: none;
  }

  .btn-primary:active {
    transform: none;
  }

  .hero-chip:hover {
    transform: none;
  }
}

.license-text {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}