/* ============================================================
 * OpenCode.cloud — main.css
 * Layer order: layout → nav → hero → why → base → pro
 *              → philosophy → founder → contact → footer
 *              → utilities (reveal, btn, eyebrow, tag, code)
 * BEM-ish naming. Section-scoped overrides via [data-bg].
 * ============================================================ */

/* ───────── Layout ───────── */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 40px);
}

.section {
  padding-block: var(--section-py);
  position: relative;
}

.section--full {
  min-height: 90vh;
  display: flex;
  align-items: center;
}

.section[data-bg="alt"] {
  background: var(--c-bg-alt);
}

.section[data-bg="dark"] {
  background:
    radial-gradient(ellipse 70% 55% at 100% 0%, rgba(0, 113, 227, 0.22) 0%, transparent 55%),
    radial-gradient(ellipse 55% 45% at 0% 100%, rgba(255, 159, 10, 0.16) 0%, transparent 55%),
    var(--c-bg-section-dark);
  color: var(--c-text-inverse);
  --c-surface: var(--c-surface-dark);
  --c-border: var(--c-border-dark);
  --c-link: var(--c-link-dark);
  --c-text: var(--c-text-inverse);
  --c-text-mute: var(--c-text-inverse-mute);
}

.section__head {
  margin-bottom: var(--sp-6);
  max-width: var(--content-max);
}

/* ───────── Eyebrow / tiny labels ───────── */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: var(--fs-eyebrow);
  font-weight: 600;
  letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase;
  color: var(--c-text-mute);
  margin-bottom: var(--sp-3);
}

.eyebrow__dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: currentColor;
}

.eyebrow--base .eyebrow__dot { background: var(--c-accent-base); }
.eyebrow--pro  .eyebrow__dot { background: var(--c-accent-pro); }

.section__title {
  font-size: var(--fs-h1);
  line-height: var(--lh-heading);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
}

.section__subtitle {
  margin-top: var(--sp-3);
  font-size: var(--fs-h3);
  color: var(--c-text-mute);
  font-weight: 400;
  max-width: 720px;
}

/* ───────── Buttons ───────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 22px;
  border-radius: var(--r-pill);
  font-size: 17px;
  font-weight: 500;
  letter-spacing: 0;
  border: 1px solid transparent;
  transition: transform var(--dur-fast) var(--ease-apple),
              background var(--dur-fast),
              color var(--dur-fast),
              border-color var(--dur-fast);
  text-decoration: none;
  white-space: nowrap;
}

.btn--primary {
  background: var(--c-accent-blue);
  color: var(--c-text-on-accent);
}

.btn--primary:hover {
  background: var(--c-link-hover);
  transform: scale(1.02);
}

.btn--secondary {
  background: transparent;
  color: var(--c-link);
  border-color: var(--c-link);
}

.btn--secondary:hover {
  background: rgba(0, 113, 227, 0.08);
}

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

.btn--ghost:hover {
  border-color: var(--c-text);
}

.btn--sm {
  padding: 8px 16px;
  font-size: var(--fs-small);
}

.section[data-bg="dark"] .btn--primary {
  background: var(--c-link-dark);
  color: var(--c-text-on-accent);
}

.section[data-bg="dark"] .btn--primary:hover {
  background: var(--c-accent-blue);
}

.section[data-bg="dark"] .btn--secondary {
  color: var(--c-link-dark);
  border-color: var(--c-link-dark);
}

.section[data-bg="dark"] .btn--secondary:hover {
  background: rgba(41, 151, 255, 0.12);
}

.btn .icon {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

/* ───────── Icon ───────── */
.icon {
  display: inline-block;
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  vertical-align: middle;
}

/* ───────── Nav ───────── */
.nav {
  position: fixed;
  top: 0;
  inset-inline: 0;
  z-index: 100;
  height: 48px;
  background: var(--c-nav-bg);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-fast) var(--ease-apple),
              background var(--dur-fast),
              color var(--dur-fast);
  color: var(--c-text);
}

.nav.is-scrolled {
  border-bottom-color: var(--c-nav-border);
}

.nav.is-on-dark {
  background: var(--c-bg-section-dark-glass);
  color: var(--c-text-inverse);
  border-bottom-color: var(--c-border-dark);
}

.nav.is-on-dark .nav__link,
.nav.is-on-dark .nav__icon-btn,
.nav.is-on-dark .nav__brand,
.nav.is-on-dark .nav__lang,
.nav.is-on-dark .nav__toggle { color: var(--c-text-inverse); }

.nav.is-on-dark .nav__brand b { color: var(--c-link-dark); }

.nav.is-on-dark .nav__lang { border-color: var(--c-border-dark); }
.nav.is-on-dark .nav__lang:hover { border-color: var(--c-text-inverse); }
.nav.is-on-dark .nav__icon-btn:hover { background: rgba(255, 255, 255, 0.10); }

.nav__inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
}

.nav__brand {
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.nav__brand b { color: var(--c-accent-blue); font-weight: 600; }

.nav__menu {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
}

.nav__link {
  color: var(--c-text);
  font-size: var(--fs-small);
  font-weight: 400;
  opacity: 0.88;
  transition: opacity var(--dur-fast);
}

.nav__link:hover { opacity: 1; }

.nav__tools {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}

.nav__icon-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--c-text);
  transition: background var(--dur-fast);
}

.nav__icon-btn:hover { background: rgba(0, 0, 0, 0.06); }
.nav__icon-btn .icon { width: 18px; height: 18px; }

.nav__lang {
  font-size: var(--fs-small);
  font-weight: 500;
  padding: 6px 12px;
  border-radius: var(--r-pill);
  border: 1px solid var(--c-border);
  color: var(--c-text);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.nav__lang:hover { border-color: var(--c-text); }

.nav__toggle {
  display: none;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  color: var(--c-text);
}

/* ───────── Hero ───────── */
.hero {
  padding-block: calc(var(--section-py) + 48px) var(--section-py);
  text-align: center;
  background:
    radial-gradient(ellipse 90% 60% at 50% 0%, rgba(0, 113, 227, 0.18) 0%, transparent 55%),
    radial-gradient(ellipse 60% 50% at 100% 100%, rgba(0, 113, 227, 0.10) 0%, transparent 60%),
    radial-gradient(ellipse 55% 45% at 0% 100%, rgba(0, 113, 227, 0.07) 0%, transparent 60%),
    var(--c-bg-page);
}

.hero__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-5);
  min-height: 80vh;
  justify-content: center;
}

.hero__title {
  font-size: var(--fs-display);
  line-height: var(--lh-display);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
  max-width: 14ch;
  text-wrap: balance;
}

.hero__subtitle {
  font-size: var(--fs-h2);
  color: var(--c-text-mute);
  font-weight: 400;
  max-width: 720px;
  line-height: var(--lh-body);
}

.hero__metrics {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(24px, 4vw, 56px);
  justify-content: center;
  margin-block: var(--sp-3);
}

.metric {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.metric__num {
  font-size: clamp(28px, 3vw, 36px);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
  color: var(--c-text);
}

.metric--blue   .metric__num { color: var(--c-layer-core); }
.metric--green  .metric__num { color: var(--c-layer-foundation); }
.metric--orange .metric__num { color: var(--c-layer-business); }

.metric__label {
  font-size: var(--fs-small);
  color: var(--c-text-mute);
}

.hero__ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  justify-content: center;
}

/* ───────── Why (value props) ───────── */
.why-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--sp-4);
}

.why-card {
  position: relative;
  padding: var(--sp-5) var(--sp-4);
  /* fallback */
  background: var(--c-surface);
  background: color-mix(in srgb, var(--c-surface) 92%, var(--card-color));
  border: 1px solid var(--c-border);
  border-color: color-mix(in srgb, var(--card-color) 22%, var(--c-border));
  border-radius: var(--r-lg);
  overflow: hidden;
  transition: border-color var(--dur-fast),
              box-shadow var(--dur-fast),
              transform var(--dur-fast) var(--ease-apple),
              background var(--dur-fast);
  --card-color: var(--c-accent-blue);
}

.why-card[data-color="blue"]   { --card-color: var(--c-layer-core); }
.why-card[data-color="purple"] { --card-color: var(--c-layer-domain); }
.why-card[data-color="green"]  { --card-color: var(--c-layer-foundation); }
.why-card[data-color="orange"] { --card-color: var(--c-layer-business); }

.why-card::before {
  content: '';
  position: absolute;
  inset: 0 0 auto 0;
  height: 4px;
  background: var(--card-color);
}

.why-card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 100% 0%, var(--card-color) 0%, transparent 55%);
  opacity: 0.18;
  pointer-events: none;
  transition: opacity var(--dur-base) var(--ease-apple);
}

.why-card > * { position: relative; z-index: 1; }

.why-card:hover {
  border-color: var(--card-color);
  box-shadow: 0 12px 32px -8px color-mix(in srgb, var(--card-color) 45%, transparent);
  transform: translateY(-3px);
}

.why-card:hover::after {
  opacity: 0.30;
}

.why-card__icon-wrap {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  margin-bottom: var(--sp-3);
  border-radius: var(--r-md);
  /* fallback */
  background: rgba(0, 113, 227, 0.18);
  background: color-mix(in srgb, var(--card-color) 18%, transparent);
  border: 1px solid color-mix(in srgb, var(--card-color) 35%, transparent);
  color: var(--card-color);
  box-shadow: 0 4px 12px -4px color-mix(in srgb, var(--card-color) 30%, transparent);
}

.why-card__icon {
  width: 30px;
  height: 30px;
  color: inherit;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.why-card__title { color: var(--card-color); }

.why-card__title {
  font-size: var(--fs-h3);
  font-weight: 600;
  margin-bottom: var(--sp-2);
  letter-spacing: var(--ls-tight);
}

.why-card__body {
  font-size: var(--fs-small);
  color: var(--c-text-mute);
  line-height: var(--lh-body);
}

/* dark 模式专属:卡片在深底上需要更高反差才"浮"得出来 */
html[data-theme="dark"] .why-card {
  background: color-mix(in srgb, var(--c-surface) 84%, var(--card-color));
  border-color: color-mix(in srgb, var(--card-color) 38%, var(--c-border));
}
html[data-theme="dark"] .why-card::after { opacity: 0.28; }
html[data-theme="dark"] .why-card:hover::after { opacity: 0.42; }
html[data-theme="dark"] .why-card__icon-wrap {
  background: color-mix(in srgb, var(--card-color) 24%, transparent);
  border-color: color-mix(in srgb, var(--card-color) 55%, transparent);
}
@media (prefers-color-scheme: dark) {
  html[data-theme="auto"] .why-card {
    background: color-mix(in srgb, var(--c-surface) 84%, var(--card-color));
    border-color: color-mix(in srgb, var(--card-color) 38%, var(--c-border));
  }
  html[data-theme="auto"] .why-card::after { opacity: 0.28; }
  html[data-theme="auto"] .why-card:hover::after { opacity: 0.42; }
  html[data-theme="auto"] .why-card__icon-wrap {
    background: color-mix(in srgb, var(--card-color) 24%, transparent);
    border-color: color-mix(in srgb, var(--card-color) 55%, transparent);
  }
}

/* ───────── Base matrix ───────── */
#base {
  background:
    radial-gradient(ellipse 45% 35% at 0% 5%,    rgba(0, 113, 227, 0.13) 0%, transparent 65%),
    radial-gradient(ellipse 45% 35% at 100% 25%, rgba(48, 209, 88, 0.13) 0%, transparent 65%),
    radial-gradient(ellipse 45% 35% at 0% 70%,   rgba(191, 90, 242, 0.11) 0%, transparent 65%),
    radial-gradient(ellipse 45% 35% at 100% 95%, rgba(255, 159, 10, 0.13) 0%, transparent 65%),
    var(--c-bg-page);
}

.base-stats {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(32px, 5vw, 80px);
  margin-bottom: var(--sp-7);
  padding-block: var(--sp-5);
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
  font-size: var(--fs-small);
  color: var(--c-text-mute);
}

.base-stats > span {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.base-stats strong {
  display: block;
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
  line-height: 1;
  margin-right: 0;
  color: var(--c-text);
}

.base-stats > span:nth-child(1) strong { color: var(--c-layer-core); }
.base-stats > span:nth-child(2) strong { color: var(--c-layer-foundation); }
.base-stats > span:nth-child(3) strong { color: var(--c-layer-business); }

.base-layer {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: var(--sp-5);
  padding: var(--sp-5);
  border-radius: var(--r-lg);
  margin-bottom: var(--sp-3);
  /* 整行该色染底 + 同色边框,卡片化 */
  background: rgba(0, 113, 227, 0.10);
  background: color-mix(in srgb, var(--c-bg-page) 82%, var(--layer-color));
  border: 1px solid rgba(0, 113, 227, 0.30);
  border: 1px solid color-mix(in srgb, var(--layer-color) 38%, var(--c-border));
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
  --layer-color: var(--c-link);
}

.base-layer[data-layer="core"]        { --layer-color: var(--c-layer-core); }
.base-layer[data-layer="foundation"]  { --layer-color: var(--c-layer-foundation); }
.base-layer[data-layer="domain"]      { --layer-color: var(--c-layer-domain); }
.base-layer[data-layer="business"]    { --layer-color: var(--c-layer-business); }

.base-layer__head {
  display: flex;
  flex-direction: column;
  gap: 6px;
  position: relative;
  padding: var(--sp-3) var(--sp-3) var(--sp-3) calc(var(--sp-3) + 4px);
  border-radius: var(--r-md);
  /* head 内部更深一档色,与整行 layer 底形成层次 */
  background: rgba(0, 113, 227, 0.18);
  background: color-mix(in srgb, var(--layer-color) 26%, var(--c-surface));
  align-self: start;
}

.base-layer__head::before {
  content: '';
  position: absolute;
  left: 0;
  top: var(--sp-3);
  bottom: var(--sp-3);
  width: 4px;
  border-radius: 2px;
  background: var(--layer-color);
}

.base-layer__name {
  font-size: var(--fs-h3);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
}

.base-layer__meta {
  font-size: var(--fs-small);
  color: var(--c-text-mute);
}

.base-layer__tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  align-content: flex-start;
}

.base-layer__lead {
  flex-basis: 100%;
  margin-top: var(--sp-2);
  font-size: var(--fs-body);
  color: var(--c-text);
  max-width: 60ch;
  line-height: var(--lh-body);
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 6px 14px;
  border-radius: var(--r-pill);
  /* fallback for browsers without color-mix support */
  background: rgba(0, 113, 227, 0.10);
  background: color-mix(in srgb, var(--layer-color, var(--c-link)) 10%, transparent);
  color: var(--layer-color, var(--c-link));
  font-size: var(--fs-small);
  font-weight: 500;
  font-family: var(--ff-mono);
  cursor: help;
  transition: background var(--dur-fast), color var(--dur-fast);
}

.tag:hover {
  background: var(--layer-color, var(--c-accent-blue));
  color: var(--c-text-on-accent);
}

/* ───────── Code block + tabs ───────── */
.code-demo {
  margin-top: var(--sp-7);
  background: var(--c-bg-dark-alt);
  color: var(--c-text-inverse);
  border-radius: var(--r-lg);
  overflow: hidden;
  box-shadow: inset 4px 0 0 var(--c-accent-base);
}

.code-tabs {
  display: flex;
  gap: 4px;
  padding: var(--sp-3) var(--sp-4) 0 var(--sp-5);
  border-bottom: 1px solid var(--c-border-dark);
  flex-wrap: wrap;
}

.code-tab {
  padding: 8px 14px;
  font-size: var(--fs-small);
  font-weight: 500;
  color: var(--c-text-inverse-mute);
  border-bottom: 2px solid transparent;
  transition: color var(--dur-fast), border-color var(--dur-fast);
  font-family: var(--ff-mono);
  --tab-color: var(--c-accent-base);
}

.code-tab[data-layer="core"]        { --tab-color: var(--c-layer-core); }
.code-tab[data-layer="foundation"]  { --tab-color: var(--c-layer-foundation); }
.code-tab[data-layer="domain"]      { --tab-color: var(--c-layer-domain); }
.code-tab[data-layer="business"]    { --tab-color: var(--c-layer-business); }

.code-tab[aria-selected="true"] {
  color: var(--c-text-inverse);
  border-bottom-color: var(--tab-color);
}

.code-tab:hover { color: var(--c-text-inverse); }

.code-panel {
  padding: var(--sp-4) var(--sp-5);
  overflow-x: auto;
}

.code-panel[hidden] { display: none; }

.code-panel pre {
  font-family: var(--ff-mono);
  font-size: var(--fs-small);
  line-height: 1.65;
  color: var(--c-text-inverse);
  white-space: pre;
}

/* ───────── Pro grid (dark section) ───────── */
.pro-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--c-border-dark);
  border: 1px solid var(--c-border-dark);
  border-radius: var(--r-lg);
  overflow: hidden;
  margin-top: var(--sp-6);
}

.pro-card {
  padding: var(--sp-5) var(--sp-4);
  background: transparent;
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  transition: background var(--dur-fast);
  position: relative;
}

.pro-card:hover {
  background: rgba(255, 255, 255, 0.04);
}

.pro-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-2);
}

.pro-card__title {
  font-size: var(--fs-h3);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
  color: var(--c-text-inverse);
  font-family: var(--ff-mono);
}

.pro-card__body {
  font-size: var(--fs-small);
  color: var(--c-text-inverse-mute);
  line-height: var(--lh-body);
  flex-grow: 1;
}

.pro-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-block: 4px;
}

.pro-card__tag {
  font-size: var(--fs-xs);
  padding: 4px 10px;
  border-radius: var(--r-pill);
  background: rgba(255, 255, 255, 0.06);
  color: var(--c-text-inverse-mute);
  border: 1px solid var(--c-border-dark);
}

.pro-card__cta {
  font-size: var(--fs-small);
  color: var(--c-link-dark);
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: auto;
}

.pro-card__cta:hover { color: var(--c-text-on-accent); }
.pro-card__cta .icon { width: 14px; height: 14px; }

/* ───────── Philosophy ───────── */
.philosophy {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--sp-5);
  margin-top: var(--sp-6);
}

.philosophy__item {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
}

.philosophy__num {
  font-size: clamp(40px, 4vw, 56px);
  font-weight: 700;
  letter-spacing: var(--ls-tight);
  color: var(--c-accent-blue);
  line-height: 1;
}

.philosophy__title {
  font-size: var(--fs-h3);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
}

.philosophy__body {
  font-size: var(--fs-body);
  color: var(--c-text-mute);
  line-height: var(--lh-body);
}

/* ───────── Founder ───────── */
.founder {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: var(--sp-4);
  max-width: 640px;
  margin-inline: auto;
}

.founder__avatar {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  background: var(--c-surface);
  border: 1.5px solid var(--c-border);
  color: var(--c-text);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-pop);
  transition: transform var(--dur-base) var(--ease-apple),
              border-color var(--dur-base) var(--ease-apple),
              color var(--dur-base) var(--ease-apple);
}

.founder__avatar:hover {
  transform: scale(1.03);
  border-color: var(--c-accent-blue);
  color: var(--c-accent-blue);
}

.founder__avatar-mark {
  width: 56%;
  height: 56%;
  display: block;
}

.founder__name {
  font-size: var(--fs-h2);
  font-weight: 600;
  letter-spacing: var(--ls-tight);
}

.founder__bio {
  font-size: var(--fs-body);
  color: var(--c-text-mute);
  line-height: var(--lh-body);
  max-width: 540px;
}

.founder__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  justify-content: center;
}

/* ───────── Contact ───────── */
.contact {
  text-align: center;
  max-width: 640px;
  margin-inline: auto;
}

.contact__quote {
  font-size: var(--fs-h2);
  font-weight: 500;
  letter-spacing: var(--ls-tight);
  margin-bottom: var(--sp-5);
}

.contact__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  justify-content: center;
}

/* ───────── Footer ───────── */
.footer {
  padding-block: var(--sp-7) var(--sp-6);
  background: var(--c-bg-section-dark);
  color: var(--c-text-inverse-mute);
  font-size: var(--fs-small);
  position: relative;
}

.footer::before {
  content: '';
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: linear-gradient(
    90deg,
    transparent 0%,
    var(--c-accent-base) 25%,
    var(--c-accent-blue) 50%,
    var(--c-accent-pro) 75%,
    transparent 100%
  );
  opacity: 0.6;
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--sp-5);
  margin-bottom: var(--sp-6);
}

.footer__bottom-meta {
  display: flex;
  gap: var(--sp-3);
  align-items: center;
}

.footer__bottom-meta a {
  color: inherit;
  text-decoration: none;
}

.footer__bottom-meta a:hover { color: var(--c-text-inverse); }

.footer__brand {
  font-size: 17px;
  font-weight: 600;
  color: var(--c-text-inverse);
  margin-bottom: var(--sp-2);
}

.footer__brand b { color: var(--c-accent-blue); font-weight: 600; }

.footer__tagline {
  font-size: var(--fs-small);
  color: var(--c-text-inverse-mute);
  max-width: 320px;
}

.footer__col-title {
  font-size: var(--fs-eyebrow);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: var(--ls-eyebrow);
  color: var(--c-text-inverse);
  margin-bottom: var(--sp-3);
}

.footer__list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}

.footer__list a:hover { color: var(--c-text-inverse); }

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  justify-content: space-between;
  padding-top: var(--sp-5);
  border-top: 1px solid var(--c-border-dark);
  font-size: var(--fs-xs);
  color: var(--c-text-inverse-mute);
}

/* ───────── Reveal animation ───────── */
[data-reveal] {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity var(--dur-base) var(--ease-out-quart),
              transform var(--dur-base) var(--ease-out-quart);
}

[data-reveal].in-view {
  opacity: 1;
  transform: none;
}

[data-reveal-delay="1"].in-view { transition-delay: 50ms; }
[data-reveal-delay="2"].in-view { transition-delay: 100ms; }
[data-reveal-delay="3"].in-view { transition-delay: 150ms; }
[data-reveal-delay="4"].in-view { transition-delay: 200ms; }

@media (prefers-reduced-motion: reduce) {
  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ───────── Skip link (a11y) ───────── */
.skip-link {
  position: absolute;
  top: -40px;
  left: 8px;
  background: var(--c-text);
  color: var(--c-bg-page);
  padding: 8px 16px;
  border-radius: var(--r-sm);
  z-index: 200;
  font-size: var(--fs-small);
  transition: top var(--dur-fast);
}

.skip-link:focus { top: 8px; }

/* ───────── Lang-specific tweaks (中文 vs 英文) ───────── */
:lang(zh) .hero__title {
  font-size: clamp(40px, 6vw, 80px);
  letter-spacing: 0;
}

:lang(zh) .eyebrow { letter-spacing: 0.08em; }

:lang(en) {
  letter-spacing: var(--ls-tight);
}

/* ───────── Responsive ───────── */
@media (max-width: 1024px) {
  .why-grid { grid-template-columns: repeat(2, 1fr); }
  .pro-grid { grid-template-columns: repeat(2, 1fr); }
  .philosophy { grid-template-columns: 1fr; gap: var(--sp-5); }
  .footer__grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .nav__menu { display: none; }
  .nav__toggle { display: inline-flex; }
  .nav.is-mobile-open .nav__menu {
    display: flex;
    position: absolute;
    top: 48px;
    right: 16px;
    flex-direction: column;
    background: var(--c-bg-page);
    border: 1px solid var(--c-border);
    padding: var(--sp-3);
    border-radius: var(--r-md);
    box-shadow: var(--shadow-pop);
    gap: var(--sp-3);
    align-items: flex-start;
  }
}

@media (max-width: 640px) {
  .why-grid { grid-template-columns: 1fr; }
  .pro-grid { grid-template-columns: 1fr; }
  .base-layer {
    grid-template-columns: 1fr;
    gap: var(--sp-3);
  }
  .footer__grid {
    grid-template-columns: 1fr;
    gap: var(--sp-4);
  }
  .hero__title { font-size: clamp(40px, 11vw, 56px); }
  .hero__subtitle { font-size: var(--fs-h3); }
  .nav__lang span { display: none; }
}

/* ───────── 404 page ───────── */
.notfound {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--sp-4);
  background: var(--c-bg-dark);
  color: var(--c-text-inverse);
  text-align: center;
  padding: var(--sp-5);
}

.notfound__num {
  font-size: clamp(96px, 18vw, 200px);
  font-weight: 700;
  letter-spacing: var(--ls-tight);
  line-height: 1;
  background: linear-gradient(135deg, #0071E3, #FF9F0A);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.notfound__msg {
  font-size: var(--fs-h2);
  color: var(--c-text-inverse);
  font-weight: 500;
}

.notfound__sub {
  color: var(--c-text-inverse-mute);
  margin-bottom: var(--sp-4);
  max-width: 480px;
}