/* Blue KKE Inc — static website
 * Apple-language design system, built on CSS custom properties.
 * Mirrors web/components/ds/tokens.ts.
 *
 * Bilingual: HTML element gets lang="en" or lang="zh"; the CSS below
 * shows/hides nodes annotated with [data-en] / [data-zh] accordingly.
 */

/* ─────────── tokens ─────────── */
:root {
  --bk-bg: #fbfbfd;
  --bk-surface: #ffffff;
  --bk-surface-alt: #f5f5f7;
  --bk-surface-dark: #1d1d1f;
  --bk-surface-darker: #000000;

  --bk-fg: #1d1d1f;
  --bk-fg-muted: #6e6e73;
  --bk-fg-subtle: #86868b;
  --bk-fg-inverse: #f5f5f7;
  --bk-fg-inverse-muted: rgba(245,245,247,.65);

  --bk-border: rgba(0,0,0,.08);
  --bk-border-strong: rgba(0,0,0,.16);
  --bk-border-inverse: rgba(255,255,255,.10);

  --bk-link: #0066cc;
  --bk-link-hover: #0077ed;

  --bk-success: #1f8e5a;
  --bk-warn: #a86c00;
  --bk-danger: #bf2c1d;

  --bk-font-display: "SF Pro Display","Söhne","Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",system-ui,sans-serif;
  --bk-font-text: "SF Pro Text","Söhne","Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",system-ui,sans-serif;
  --bk-font-mono: "SF Mono",ui-monospace,"JetBrains Mono",Menlo,monospace;

  --bk-r-sm: 8px;
  --bk-r-md: 12px;
  --bk-r-lg: 18px;
  --bk-r-xl: 22px;
  --bk-r-pill: 980px;

  --bk-container: 1024px;
}

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

html, body { margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bk-bg);
  color: var(--bk-fg);
  font-family: var(--bk-font-text);
  font-size: 17px;
  line-height: 1.47;
  letter-spacing: -0.022em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, svg { display: block; max-width: 100%; }

a { color: inherit; }

button { font-family: inherit; cursor: pointer; }

ul, ol { padding: 0; margin: 0; list-style: none; }

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: rgba(0,0,0,.18); border-radius: 8px; }
::-webkit-scrollbar-thumb:hover { background: rgba(0,0,0,.28); }

/* ─────────── bilingual ─────────── */
html[lang="en"] [data-zh] { display: none !important; }
html[lang="zh"] [data-en] { display: none !important; }

/* ─────────── nav ─────────── */
.bk-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(251,251,253,.78);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--bk-border);
}
.bk-nav__inner {
  max-width: var(--bk-container);
  margin: 0 auto;
  height: 44px;
  padding: 0 22px;
  display: flex;
  align-items: center;
  font-size: 12px;
}
.bk-nav__brand {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--bk-fg);
  text-decoration: none;
  margin-right: 16px;
}
.bk-nav__brand-text {
  font-family: var(--bk-font-display);
  font-weight: 500;
  font-size: 14px;
  letter-spacing: -0.01em;
}
.bk-nav__items {
  display: flex;
  align-items: center;
  flex: 1;
}
.bk-nav__item {
  color: var(--bk-fg-muted);
  padding: 0 10px;
  height: 44px;
  line-height: 44px;
  text-decoration: none;
  font-size: 12px;
  transition: color .2s;
}
.bk-nav__item:hover { color: var(--bk-fg); }
.bk-nav__item.is-active { color: var(--bk-fg); }
.bk-nav__right {
  display: flex;
  align-items: center;
  gap: 14px;
}
.bk-nav__lang {
  background: none;
  border: 0;
  color: var(--bk-fg-muted);
  font-size: 12px;
  padding: 0;
}
.bk-nav__lang:hover { color: var(--bk-fg); }
.bk-nav__cta {
  background: var(--bk-fg);
  color: var(--bk-fg-inverse);
  padding: 5px 11px;
  border-radius: var(--bk-r-pill);
  font-size: 12px;
  font-weight: 500;
  text-decoration: none;
  letter-spacing: -0.005em;
}

/* ─────────── footer ─────────── */
.bk-footer {
  background: var(--bk-surface-alt);
  color: var(--bk-fg-muted);
  font-size: 12px;
  line-height: 1.5;
  padding-top: 40px;
}
.bk-footer__inner {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 22px;
}
.bk-footer__top {
  padding-bottom: 16px;
  border-bottom: 1px solid var(--bk-border);
  font-size: 12px;
}
.bk-footer__top a { color: var(--bk-link); text-decoration: none; }
.bk-footer__cols {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  padding: 24px 0;
}
.bk-footer__col-h {
  color: var(--bk-fg);
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 10px;
}
.bk-footer__col li { margin-bottom: 6px; }
.bk-footer__col a {
  color: var(--bk-fg-muted);
  text-decoration: none;
  font-size: 12px;
}
.bk-footer__col a:hover { color: var(--bk-fg); }
.bk-footer__legal {
  border-top: 1px solid var(--bk-border);
  padding: 14px 0 22px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 11px;
}
.bk-footer__legal a { color: var(--bk-fg-muted); text-decoration: none; }
.bk-footer__legal-links { display: flex; gap: 16px; }

/* ─────────── primitives ─────────── */
.bk-eyebrow {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -0.005em;
  color: var(--bk-link);
  margin-bottom: 6px;
}
.bk-eyebrow.is-onDark { color: var(--bk-fg-inverse-muted); }

.bk-headline {
  margin: 0;
  font-family: var(--bk-font-display);
  color: var(--bk-fg);
  font-weight: 600;
  text-align: center;
}
.bk-headline.is-left { text-align: left; }
.bk-headline.is-onDark { color: var(--bk-fg-inverse); }
.bk-headline--xl { font-size: 80px; line-height: 1.05; letter-spacing: -0.05em; }
.bk-headline--lg { font-size: 56px; line-height: 1.07; letter-spacing: -0.045em; }
.bk-headline--md { font-size: 40px; line-height: 1.10; letter-spacing: -0.035em; }
.bk-headline--sm { font-size: 28px; line-height: 1.15; letter-spacing: -0.025em; }

.bk-subhead {
  margin: 0;
  font-family: var(--bk-font-text);
  font-weight: 400;
  color: var(--bk-fg);
  text-align: center;
}
.bk-subhead.is-left { text-align: left; }
.bk-subhead.is-muted { color: var(--bk-fg-muted); }
.bk-subhead.is-onDark { color: var(--bk-fg-inverse); }
.bk-subhead.is-onDark.is-muted { color: var(--bk-fg-inverse-muted); }
.bk-subhead--lg { font-size: 24px; line-height: 1.33; letter-spacing: -0.012em; }
.bk-subhead--md { font-size: 19px; line-height: 1.42; letter-spacing: -0.012em; }
.bk-subhead--sm { font-size: 17px; line-height: 1.47; letter-spacing: -0.022em; }

.bk-cta-group {
  display: flex;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}
.bk-cta-group.is-left { justify-content: flex-start; }
.bk-cta {
  color: var(--bk-link);
  background: transparent;
  padding: 0;
  border-radius: var(--bk-r-pill);
  font-size: 17px;
  font-weight: 400;
  text-decoration: none;
  letter-spacing: -0.022em;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border: 0;
  font-family: inherit;
}
.bk-cta--primary {
  color: #fff;
  background: var(--bk-link);
  padding: 12px 22px;
}
.bk-cta--primary:hover { background: var(--bk-link-hover); }
.bk-chev::after {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  border-right: 1.5px solid currentColor;
  border-top: 1.5px solid currentColor;
  transform: rotate(45deg) translate(-1px, 1px);
  margin-left: 4px;
}

.bk-hairline { height: 1px; background: var(--bk-border); }
.bk-hairline.is-onDark { background: var(--bk-border-inverse); }

.bk-container {
  max-width: var(--bk-container);
  margin: 0 auto;
  padding-left: 22px;
  padding-right: 22px;
}

.bk-hero {
  padding: 88px 22px 48px;
  text-align: center;
}
.bk-hero__sub {
  max-width: 720px;
  margin: 14px auto 0;
}
.bk-hero__cta {
  margin-top: 22px;
}

/* ─────────── home ─────────── */
.bk-home-hero {
  padding: 64px 22px 88px;
  background: var(--bk-bg);
  text-align: center;
  position: relative;
  overflow: hidden;
}
.bk-home-hero__sheen {
  position: absolute;
  top: 40px;
  left: 50%;
  transform: translateX(-50%);
  width: 720px;
  height: 480px;
  border-radius: 50%;
  background: radial-gradient(closest-side, rgba(120,140,180,.18), rgba(120,140,180,0) 70%);
  pointer-events: none;
}
.bk-home-hero__inner { position: relative; }
.bk-home-hero__mark { display: flex; justify-content: center; margin-bottom: 32px; }
.bk-home-hero__line { margin-top: 14px; font-size: 12px; color: var(--bk-fg-subtle); }

.bk-tiles {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  max-width: var(--bk-container);
  margin: 0 auto;
  padding: 0 22px 14px;
}
.bk-tile {
  border-radius: var(--bk-r-xl);
  height: 560px;
  padding: 60px 32px 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  overflow: hidden;
  position: relative;
}
.bk-tile.is-dark { background: var(--bk-surface-darker); color: var(--bk-fg-inverse); }
.bk-tile.is-light { background: var(--bk-surface-alt); color: var(--bk-fg); }
.bk-tile__head { max-width: 480px; }
.bk-tile__art { flex: 1; display: flex; align-items: center; justify-content: center; width: 100%; margin-top: 24px; }

.bk-quad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  max-width: var(--bk-container);
  margin: 0 auto;
  padding: 14px 22px;
}
.bk-quad__tile {
  border-radius: var(--bk-r-xl);
  padding: 36px 22px 24px;
  height: 360px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  text-align: center;
}
.bk-quad__tile.is-dark { background: var(--bk-surface-dark); color: var(--bk-fg-inverse); }
.bk-quad__tile.is-light { background: var(--bk-surface-alt); color: var(--bk-fg); }
.bk-quad__tile a { color: var(--bk-link); text-decoration: none; font-size: 14px; }

.bk-stats-wrap { max-width: var(--bk-container); margin: 14px auto 0; padding: 0 22px; }
.bk-stats {
  background: var(--bk-surface-darker);
  color: var(--bk-fg-inverse);
  border-radius: var(--bk-r-xl);
  padding: 64px 32px;
  text-align: center;
}
.bk-stats__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-top: 40px;
}
.bk-stats__num {
  font-family: var(--bk-font-display);
  font-size: 56px;
  font-weight: 600;
  letter-spacing: -0.04em;
  line-height: 1;
}
.bk-stats__label {
  font-size: 13px;
  color: var(--bk-fg-inverse-muted);
  margin-top: 8px;
}

/* ─────────── compare ─────────── */
.bk-compare-wrap { max-width: var(--bk-container); margin: 0 auto; padding: 88px 22px; }
.bk-compare {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 32px;
}
.bk-compare__col {
  background: var(--bk-surface);
  color: var(--bk-fg);
  border: 1px solid var(--bk-border);
  border-radius: var(--bk-r-lg);
  padding: 28px 24px;
  text-align: left;
}
.bk-compare__col.is-featured {
  background: var(--bk-surface-darker);
  color: var(--bk-fg-inverse);
  border-color: var(--bk-border-inverse);
}
.bk-compare__tag {
  font-size: 13px;
  font-weight: 500;
  color: var(--bk-fg-muted);
  margin-bottom: 4px;
}
.bk-compare__col.is-featured .bk-compare__tag { color: var(--bk-fg-inverse-muted); }
.bk-compare__rows { display: flex; flex-direction: column; gap: 12px; }
.bk-compare__row {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--bk-fg-muted);
}
.bk-compare__col.is-featured .bk-compare__row { color: var(--bk-fg-inverse-muted); }
.bk-icon {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
}

/* ─────────── services / cards ─────────── */
.bk-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  max-width: var(--bk-container);
  margin: 0 auto;
  padding: 0 22px 88px;
}
.bk-card {
  border-radius: var(--bk-r-xl);
  padding: 52px 36px 36px;
  min-height: 320px;
  text-align: left;
}
.bk-card.is-light { background: var(--bk-surface-alt); color: var(--bk-fg); }
.bk-card.is-dark { background: var(--bk-surface-dark); color: var(--bk-fg-inverse); }
.bk-card__eyebrow {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--bk-link);
}
.bk-card.is-dark .bk-card__eyebrow { color: var(--bk-fg-inverse-muted); }
.bk-card__sub { margin-top: 10px; max-width: 420px; color: var(--bk-fg-muted); }
.bk-card.is-dark .bk-card__sub { color: var(--bk-fg-inverse-muted); }
.bk-card__link { display: inline-block; margin-top: 18px; font-size: 14px; color: var(--bk-link); text-decoration: none; }
.bk-card.is-dark .bk-card__link { color: #fff; }

/* ─────────── process ─────────── */
.bk-process { max-width: 880px; margin: 0 auto; padding: 0 22px 88px; }
.bk-process__row {
  display: grid;
  grid-template-columns: 80px 1fr 120px;
  gap: 24px;
  padding: 36px 0;
  border-top: 1px solid var(--bk-border);
  align-items: baseline;
}
.bk-process__row:last-of-type { border-bottom: 1px solid var(--bk-border); }
.bk-process__num,
.bk-process__days {
  font-family: var(--bk-font-mono);
  font-size: 12px;
  color: var(--bk-fg-subtle);
  letter-spacing: 0.06em;
}
.bk-process__days { font-size: 11px; text-align: right; }

/* ─────────── pricing FAQ ─────────── */
.bk-faq { max-width: 720px; margin: 0 auto; padding: 0 22px 88px; }
.bk-faq__item { border-top: 1px solid var(--bk-border); padding: 24px 0; }
.bk-faq__item:last-of-type { border-bottom: 1px solid var(--bk-border); }
.bk-faq__q { font-size: 17px; font-weight: 500; color: var(--bk-fg); }
.bk-faq__a { margin-top: 6px; font-size: 15px; color: var(--bk-fg-muted); line-height: 1.55; }

/* ─────────── work ─────────── */
.bk-work {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  max-width: var(--bk-container);
  margin: 0 auto;
  padding: 0 22px 88px;
}
.bk-work__card {
  border-radius: var(--bk-r-xl);
  padding: 36px 32px;
  min-height: 380px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}
.bk-work__cat {
  font-size: 12px;
  font-weight: 500;
  opacity: .6;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.bk-work__name { margin-top: 12px; font-size: 14px; color: var(--bk-fg-muted); }
.bk-work__card.is-dark .bk-work__name { color: var(--bk-fg-inverse-muted); }
.bk-work__foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.bk-work__link {
  color: var(--bk-link);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
}
.bk-work__card.is-dark .bk-work__link { color: #fff; }

/* ─────────── contact form ─────────── */
.bk-contact {
  max-width: 880px;
  margin: 0 auto;
  padding: 0 22px 88px;
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: 32px;
}
.bk-form {
  background: var(--bk-surface);
  border: 1px solid var(--bk-border);
  border-radius: var(--bk-r-lg);
  padding: 36px;
}
.bk-form__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}
.bk-field { display: block; }
.bk-field.is-wide { grid-column: 1 / -1; }
.bk-field__label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--bk-fg);
  margin-bottom: 6px;
}
.bk-input, .bk-textarea, .bk-select {
  width: 100%;
  border: 1px solid var(--bk-border);
  border-radius: var(--bk-r-sm);
  padding: 10px 12px;
  font-size: 14px;
  font-family: var(--bk-font-text);
  color: var(--bk-fg);
  background: var(--bk-surface);
  outline: none;
}
.bk-input:focus, .bk-textarea:focus, .bk-select:focus {
  border-color: var(--bk-fg);
}
.bk-textarea { resize: vertical; min-height: 92px; }
.bk-select { appearance: none; -webkit-appearance: none; background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'><path d='M2 4 L6 8 L10 4' stroke='%236e6e73' stroke-width='1.5' fill='none'/></svg>"); background-repeat: no-repeat; background-position: right 12px center; }
.bk-form__foot {
  margin-top: 28px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.bk-form__note { font-size: 12px; color: var(--bk-fg-subtle); }
.bk-form__submit {
  background: var(--bk-fg);
  color: var(--bk-fg-inverse);
  border: 0;
  padding: 11px 22px;
  border-radius: var(--bk-r-pill);
  font-size: 15px;
  font-weight: 500;
}
.bk-form__submit:hover { opacity: .85; }
.bk-aside h4 { font-size: 13px; font-weight: 600; color: var(--bk-fg); letter-spacing: 0.04em; margin: 0 0 14px; }
.bk-aside ul li { margin-bottom: 12px; font-size: 14px; color: var(--bk-fg-muted); }
.bk-aside a { color: var(--bk-link); text-decoration: none; }

/* ─────────── brand page specifics ─────────── */
.bk-brand-hero {
  background: #f5f0e8;
  border-radius: var(--bk-r-xl);
  padding: 88px 22px;
  margin: 0 auto 14px;
  max-width: var(--bk-container);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
}
.bk-brand-hero.is-dark {
  background: #16161a;
  color: var(--bk-fg-inverse);
}
.bk-brand-section { max-width: var(--bk-container); margin: 40px auto 0; padding: 0 22px; }
.bk-brand-ladder {
  background: var(--bk-surface-alt);
  border-radius: var(--bk-r-lg);
  padding: 40px 28px;
  display: flex;
  align-items: flex-end;
  justify-content: space-around;
  gap: 24px;
  flex-wrap: wrap;
  margin-top: 22px;
}
.bk-brand-size {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}
.bk-brand-size__label {
  font-family: var(--bk-font-mono);
  font-size: 11px;
  color: var(--bk-fg-subtle);
  letter-spacing: 0.06em;
}
.bk-metals {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-top: 22px;
}
.bk-metal-card {
  background: var(--bk-surface);
  border: 1px solid var(--bk-border);
  border-radius: var(--bk-r-lg);
  padding: 32px 20px 20px;
  text-align: center;
}
.bk-metal-card__well {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 140px;
  background: #0a0a0a;
  border-radius: var(--bk-r-md);
  margin-bottom: 16px;
}
.bk-metal-card__name {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--bk-fg);
}
.bk-metal-card__sub { font-size: 11px; color: var(--bk-fg-muted); margin-top: 4px; }

.bk-lockups {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 22px;
}
.bk-lockup {
  border-radius: var(--bk-r-lg);
  padding: 64px 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  min-height: 200px;
}
.bk-lockup.is-light { background: #f5f0e8; border: 1px solid var(--bk-border); }
.bk-lockup.is-dark  { background: #16161a; border: 1px solid var(--bk-border-inverse); color: var(--bk-fg-inverse); }
.bk-lockup__text {
  font-family: var(--bk-font-display);
  font-weight: 500;
  font-size: 22px;
  letter-spacing: -0.01em;
}

.bk-donts {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-top: 22px;
  margin-bottom: 88px;
}
.bk-dont {
  background: var(--bk-surface);
  border: 1px solid var(--bk-border);
  border-radius: var(--bk-r-lg);
  padding: 24px 16px;
  text-align: center;
  position: relative;
}
.bk-dont__well {
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.bk-dont__x {
  position: absolute;
  top: 10px;
  right: 10px;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bk-danger);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  font-weight: 500;
}
.bk-dont__label {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--bk-border);
  font-size: 12px;
  font-weight: 500;
  color: var(--bk-fg);
}

/* ─────────── closing CTA ─────────── */
.bk-closing {
  background: var(--bk-bg);
  padding: 88px 22px;
  text-align: center;
}
.bk-closing__sub { max-width: 540px; margin: 14px auto 0; color: var(--bk-fg-muted); }

/* ─────────── responsive ─────────── */
@media (max-width: 900px) {
  .bk-tiles, .bk-cards, .bk-work, .bk-lockups,
  .bk-compare, .bk-quad, .bk-stats__grid,
  .bk-footer__cols, .bk-metals, .bk-donts,
  .bk-form__grid, .bk-contact {
    grid-template-columns: 1fr;
  }
  .bk-tile { height: auto; padding: 40px 22px 28px; }
  .bk-headline--xl { font-size: 56px; }
  .bk-headline--lg { font-size: 40px; }
  .bk-headline--md { font-size: 30px; }
  .bk-process__row { grid-template-columns: 60px 1fr; }
  .bk-process__days { display: none; }
  .bk-nav__items { display: none; }
}