/* LetKite marketing site — static styles, no JS required. */

:root {
  --ink: #0B1A33;
  --ink-2: #3A4556;
  --muted: #52607A;
  --line: #D5DEE8;
  --line-soft: #E1E7EF;
  --bg: #F5F7FA;
  --bg-2: #E8EEF5;
  --surface: #FFFFFF;
  --brand: #0E358C;
  --brand-2: #1C79BE;
  --teal: #0B7C90;
  --teal-bright: #08A0B9;
  --mint: #A8EDC3;
  --mint-bg: #EFFAF4;
  --tint: #F1F8FB;
  --dark: #0B1A33;
  --dark-card: #12244A;
  --dark-line: #22386A;
  --dark-text: #B8C5DA;
  --dark-accent: #6CD8BE;
  --radius: 16px;
  --gutter: 80px;
  --max: 1440px;
  --font: 'IBM Plex Sans', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-zh: 'Noto Sans SC', 'IBM Plex Sans', system-ui, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: var(--font); line-height: 1.5; }
html[lang="zh-CN"] body { font-family: var(--font-zh); }
img, svg { display: block; max-width: 100%; }
a { color: var(--ink); }
a:hover { color: var(--teal); }
h1, h2, h3, p { margin: 0; }

.container { width: 100%; max-width: var(--max); margin: 0 auto; padding: 0 var(--gutter); }
.section { padding: 96px 0; }
.section--tight { padding: 72px 0; }
.section--dark { background: var(--dark); color: #F5F7FA; }
.section--band { background: var(--bg-2); }
.section--white { background: var(--surface); border-top: 1px solid var(--line); }

.eyebrow { font-family: var(--mono); font-size: 13px; letter-spacing: 1px; color: var(--teal); text-transform: uppercase; }
html[lang="zh-CN"] .eyebrow { font-family: var(--font-zh); letter-spacing: 2px; text-transform: none; }
.section--dark .eyebrow { color: var(--dark-accent); }
.h1 { font-weight: 700; font-size: clamp(44px, 6vw, 80px); line-height: 1.02; letter-spacing: -0.025em; }
.h2 { font-weight: 700; font-size: clamp(32px, 3.6vw, 52px); line-height: 1.06; letter-spacing: -0.02em; }
.h2--sm { font-size: clamp(28px, 3vw, 44px); }
html[lang="zh-CN"] .h1, html[lang="zh-CN"] .h2 { line-height: 1.22; letter-spacing: 0; }
.lead { font-size: clamp(17px, 1.4vw, 20px); line-height: 1.6; color: var(--ink-2); }
.body { font-size: 16px; line-height: 1.6; color: var(--ink-2); }
.small { font-size: 13px; line-height: 1.6; color: var(--muted); }
.section--dark .lead, .section--dark .body { color: var(--dark-text); }

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; min-height: 52px; padding: 0 26px; border-radius: 12px; font-weight: 600; font-size: 16px; text-decoration: none; border: 1.5px solid transparent; font-family: inherit; cursor: pointer; }
.btn--primary { background: var(--brand); color: #FFFFFF; }
.btn--primary:hover { color: #FFFFFF; background: #0B2B73; }
.btn--outline { border-color: var(--ink); color: var(--ink); background: transparent; }
.btn--light { background: #F5F7FA; color: var(--ink); }
.btn--sm { min-height: 44px; padding: 0 20px; font-size: 15px; border-radius: 10px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 14px; }

/* Header */
.site-header { border-bottom: 1px solid var(--line); background: var(--bg); }
.site-header .container { display: flex; align-items: center; gap: 40px; min-height: 80px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 700; font-size: 24px; letter-spacing: -0.02em; color: var(--ink); }
.brand img { width: 36px; height: 36px; }
.brand small { font-family: var(--font-zh); font-size: 16px; font-weight: 700; }
.nav { display: flex; gap: 28px; flex-grow: 1; font-size: 15px; font-weight: 500; }
.nav a { text-decoration: none; }
.nav a[aria-current="page"] { color: var(--brand); font-weight: 600; }
.lang { display: inline-flex; align-items: center; gap: 6px; min-height: 44px; font-size: 14px; color: var(--muted); text-decoration: none; }

/* Hero */
.hero .container { display: grid; grid-template-columns: minmax(0, 640px) minmax(0, 1fr); gap: 40px; align-items: center; padding-top: 80px; padding-bottom: 56px; }
.hero__copy { display: flex; flex-direction: column; gap: 28px; }
.diagram { width: 100%; height: auto; }

/* Proof strip */
.strip { background: var(--surface); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.strip .container { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 32px; padding-top: 24px; padding-bottom: 24px; }
.strip strong { display: block; font-size: 16px; font-weight: 600; }
.strip span { font-size: 14px; color: var(--muted); }

/* Split layouts */
.split { display: grid; grid-template-columns: minmax(0, 520px) minmax(0, 1fr); gap: 72px; align-items: center; }
.split--narrow { grid-template-columns: minmax(0, 440px) minmax(0, 1fr); gap: 56px; }
.stack { display: flex; flex-direction: column; gap: 20px; }
.section-head { display: flex; justify-content: space-between; align-items: flex-end; gap: 40px; margin-bottom: 44px; }
.section-head > p { max-width: 460px; }

/* Layer diagram */
.layers { display: flex; flex-direction: column; gap: 14px; }
.layer { display: grid; grid-template-columns: 140px 1fr auto; align-items: center; gap: 24px; min-height: 104px; padding: 0 32px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.layer__tag { font-family: var(--mono); font-size: 12px; letter-spacing: 1px; color: var(--muted); }
.layer__name { font-size: 20px; font-weight: 600; }
.layer__role { font-size: 15px; color: var(--muted); }
.layer--core { min-height: 120px; background: var(--dark); border-color: var(--dark); color: #F5F7FA; }
.layer--core .layer__tag { color: var(--dark-accent); }
.layer--core .layer__role { color: var(--dark-text); }
.layer--core .layer__name { display: flex; align-items: center; gap: 12px; font-size: 24px; font-weight: 700; }
.layer--core .layer__name img { width: 40px; height: 40px; }

/* Cards */
.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 32px; }
.card-dark { background: var(--dark-card); border: 1px solid var(--dark-line); border-radius: 18px; padding: 32px; display: flex; flex-direction: column; gap: 20px; }
.card-dark h3 { font-size: 24px; font-weight: 600; }
.card-dark p { font-size: 16px; line-height: 1.6; color: var(--dark-text); }
.feature h3 { font-size: 21px; font-weight: 600; margin-bottom: 12px; }

/* Plans */
.plan { border: 1.5px solid var(--line); border-radius: 18px; padding: 36px; display: flex; flex-direction: column; gap: 18px; }
.plan--pro { border-color: var(--brand); background: var(--mint-bg); }
.plan__title { display: flex; align-items: baseline; flex-wrap: wrap; gap: 12px; }
.plan__title h3 { font-size: 28px; font-weight: 700; }
.plan__title span { font-size: 15px; color: var(--muted); }
.plan--pro .plan__title span { color: var(--brand); }
.plan ul { margin: 0; padding-left: 20px; display: flex; flex-direction: column; gap: 10px; font-size: 16px; line-height: 1.45; color: var(--ink-2); }
.plan > .btn, .plan form { margin-top: auto; }
.waitlist { display: flex; flex-direction: column; gap: 10px; }
.waitlist label { font-size: 14px; font-weight: 600; }
.waitlist__row { display: flex; gap: 10px; }
.waitlist input[type="email"] { flex-grow: 1; min-height: 52px; padding: 0 16px; border: 1.5px solid #8494AA; border-radius: 12px; font: inherit; font-size: 16px; background: #FFFFFF; }
.waitlist fieldset { border: 0; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 18px; font-size: 14px; color: var(--ink-2); }
.waitlist legend { padding: 0; margin-bottom: 6px; font-size: 13px; color: var(--muted); }
.waitlist fieldset label { display: inline-flex; align-items: center; gap: 6px; font-weight: 400; }

/* FAQ */
.faq { display: grid; grid-template-columns: 320px 1fr; gap: 80px; }
.faq h3 { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.faq p { font-size: 15px; line-height: 1.6; color: var(--ink-2); }

/* Footer */
.site-footer { background: var(--dark); color: var(--dark-text); padding: 56px 0; }
.site-footer .row { display: flex; align-items: center; flex-wrap: wrap; gap: 32px 48px; margin-bottom: 28px; font-size: 15px; }
.site-footer .brand { color: #F5F7FA; flex-grow: 1; font-size: 24px; }
.site-footer .brand img { width: 32px; height: 32px; }
.site-footer a { color: #F5F7FA; text-decoration: none; }
.site-footer p { font-size: 13px; line-height: 1.6; max-width: 900px; }

/* Compare page */
.compare-intro { display: flex; justify-content: space-between; align-items: flex-end; gap: 64px; padding: 72px 0 40px; }
.compare-intro p { max-width: 460px; }
.compare-wrap { overflow-x: auto; }
.compare { width: 100%; min-width: 900px; border-collapse: collapse; table-layout: fixed; background: var(--surface); border: 1px solid var(--line); font-size: 15px; line-height: 1.4; }
.compare col.c-label { width: 30%; }
.compare thead th { vertical-align: top; text-align: left; padding: 24px 16px; font-weight: 400; background: var(--bg); border-bottom: 1px solid var(--line); }
.compare thead th:first-child { background: var(--bg); }
.compare .plan-name { display: block; font-size: 22px; font-weight: 700; margin-bottom: 6px; }
.compare .plan-sub { display: block; font-size: 14px; color: var(--muted); }
.compare thead .btn { margin-top: 16px; width: 100%; }
.compare thead th.is-pro { background: var(--dark); color: #F5F7FA; border-radius: 16px 16px 0 0; }
.compare thead th.is-pro .plan-sub { color: var(--dark-text); }
.badge { display: inline-block; margin-left: 8px; font-size: 12px; font-weight: 600; color: var(--ink); background: var(--mint); border-radius: 999px; padding: 3px 10px; vertical-align: middle; }
.compare tbody th[scope="row"] { text-align: left; font-weight: 500; padding: 16px 20px; }
.compare td { padding: 16px; color: var(--ink-2); vertical-align: middle; }
.compare tbody tr { border-top: 1px solid var(--line-soft); }
.compare td.is-pro { background: var(--tint); }
.compare tr.group th { padding: 28px 20px 8px; font-size: 13px; font-weight: 600; letter-spacing: 1.5px; color: var(--teal); text-align: left; }
.compare tr.group { border-top: 0; }
.mark { display: inline-flex; align-items: center; gap: 8px; }
.mark::before { content: ""; flex-shrink: 0; }
.mark--yes::before { width: 18px; height: 18px; border-radius: 50%; background: var(--teal); }
.mark--part::before { width: 14px; height: 14px; border-radius: 50%; border: 2px solid var(--teal); background: linear-gradient(90deg, var(--teal) 50%, transparent 50%); }
.mark--no { color: #6A7890; }
.mark--no::before { width: 14px; height: 2px; background: #8494AA; }
.legend { display: flex; flex-wrap: wrap; gap: 28px; padding-top: 24px; font-size: 13px; color: var(--muted); }
.compare-cta { display: grid; grid-template-columns: minmax(0, 560px) 1fr; gap: 64px; padding: 56px 0 96px; }

/* Screen-reader only */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }

/* Responsive */
@media (max-width: 1100px) {
  :root { --gutter: 40px; }
  .hero .container, .split, .split--narrow { grid-template-columns: 1fr; }
  .strip .container { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-3 { grid-template-columns: 1fr; gap: 24px; }
  .faq { grid-template-columns: 1fr; gap: 32px; }
  .nav { display: none; }
  .site-header .container { justify-content: space-between; gap: 16px; }
}
@media (max-width: 760px) {
  :root { --gutter: 20px; }
  .section { padding: 56px 0; }
  .section--tight { padding: 48px 0; }
  .hero .container { padding-top: 40px; }
  .strip .container { grid-template-columns: 1fr; gap: 16px; }
  .grid-2 { grid-template-columns: 1fr; }
  .section-head { flex-direction: column; align-items: flex-start; gap: 16px; margin-bottom: 28px; }
  .layer { grid-template-columns: 1fr; gap: 4px; padding: 16px 20px; min-height: 0; }
  .card-dark, .plan { padding: 22px; }
  .waitlist__row { flex-direction: column; }
  .btn-row .btn { width: 100%; }
  .site-header .btn { display: none; }
  .compare-intro { flex-direction: column; align-items: flex-start; gap: 20px; padding-top: 40px; }
  .compare-cta { grid-template-columns: 1fr; gap: 24px; }
}

/* ---- Production additions (not in the design handoff) ---- */

/* Mobile menu: shown below 1100px, where the primary nav is hidden. No JS: <details>. */
.menu { display: none; position: relative; }
.menu > summary { list-style: none; display: inline-flex; align-items: center; justify-content: center; width: 44px; height: 44px; border: 1.5px solid var(--line); border-radius: 10px; color: var(--ink); cursor: pointer; }
.menu > summary::-webkit-details-marker { display: none; }
.menu[open] > summary { border-color: var(--ink); }
.menu__panel { position: absolute; right: 0; top: calc(100% + 8px); z-index: 20; min-width: 240px; padding: 8px; display: flex; flex-direction: column; background: var(--surface); border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 12px 32px rgba(11, 26, 51, 0.12); }
.menu__panel a { padding: 12px 14px; border-radius: 8px; font-size: 16px; font-weight: 500; text-decoration: none; }
.menu__panel a:hover { background: var(--bg); }
.menu__panel a[aria-current="page"] { color: var(--brand); font-weight: 600; }
.menu__panel .menu__cta { margin-top: 6px; background: var(--brand); color: #FFFFFF; text-align: center; font-weight: 600; }
.menu__panel .menu__cta:hover { background: #0B2B73; color: #FFFFFF; }

/* Waitlist spam trap: off-screen for people, still filled in by naive bots. */
.hp { position: absolute; left: -10000px; width: 1px; height: 1px; overflow: hidden; }

/* Thanks / 404 pages */
.status-page { padding: 120px 0 144px; }
.status-page .stack { max-width: 680px; gap: 24px; }

@media (max-width: 1100px) {
  .menu { display: block; }
  .site-header .container { justify-content: flex-start; }
  .site-header .brand { margin-right: auto; }
}
@media (max-width: 760px) {
  .status-page { padding: 64px 0 80px; }
}