/* FlowSmith — dark, high-contrast landing page. No frameworks, no external fonts. */

:root {
  --bg: #0a0e10;
  --bg-soft: #0e1417;
  --surface: #111a1e;
  --surface-2: #162126;
  --line: rgba(255, 255, 255, 0.09);
  --line-strong: rgba(255, 255, 255, 0.18);
  --text: #eaf2f4;
  --muted: #9fb0b7;
  --dim: #71838b;
  --accent: #d4ff4f;
  --accent-soft: rgba(212, 255, 79, 0.12);
  --mint: #7cf5c8;
  --radius: 18px;
  --radius-sm: 12px;
  --wrap: 1120px;
  --pad: clamp(20px, 5vw, 40px);
  --section: clamp(64px, 9vw, 118px);
  --shadow: 0 24px 60px -30px rgba(0, 0, 0, 0.9);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
p { margin: 0 0 1em; }
h1, h2, h3 { margin: 0 0 0.5em; line-height: 1.08; letter-spacing: -0.025em; font-weight: 620; }
h1 { font-size: clamp(2.5rem, 6.2vw, 4.5rem); }
h2 { font-size: clamp(1.9rem, 3.6vw, 2.9rem); }
h3 { font-size: 1.15rem; letter-spacing: -0.01em; }
::selection { background: var(--accent); color: #0a0e10; }

html[data-lang="zh"] .lang-en-only { display: none !important; }
html[data-lang="en"] .lang-zh-only { display: none !important; }
html[data-lang="zh"] body { line-height: 1.75; }
html[data-lang="zh"] h1, html[data-lang="zh"] h2, html[data-lang="zh"] h3 { letter-spacing: 0; line-height: 1.2; }

.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 var(--pad); }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--accent); color: #0a0e10; padding: 10px 16px; border-radius: 8px;
}
.skip:focus { left: 12px; top: 12px; }

/* ---------- nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(10, 14, 16, 0.72);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid var(--line);
}
.nav-inner { display: flex; align-items: center; gap: 24px; height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 640; letter-spacing: -0.02em; }
.brand-mark {
  width: 30px; height: 30px; border-radius: 9px;
  display: grid; place-items: center;
  background: var(--accent); color: #0a0e10;
}
.brand-mark svg { width: 18px; height: 18px; }
.brand-name { font-size: 1.05rem; }
.nav-links { display: flex; gap: 28px; margin-left: auto; font-size: 0.92rem; color: var(--muted); }
.nav-links a { transition: color 0.18s ease; }
.nav-links a:hover { color: var(--text); }
.nav-actions { display: flex; align-items: center; gap: 10px; margin-left: auto; }
.nav-links + .nav-actions { margin-left: 8px; }
.lang {
  background: transparent; border: 1px solid var(--line-strong); color: var(--muted);
  font: inherit; font-size: 0.82rem; padding: 6px 12px; border-radius: 999px; cursor: pointer;
  transition: all 0.18s ease;
}
.lang:hover { color: var(--text); border-color: var(--accent); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border-radius: 999px; padding: 14px 26px;
  font-size: 0.95rem; font-weight: 600; letter-spacing: -0.01em;
  border: 1px solid transparent; cursor: pointer;
  transition: transform 0.16s ease, box-shadow 0.16s ease, background 0.16s ease, border-color 0.16s ease;
}
.btn:active { transform: translateY(1px) scale(0.995); }
.btn-primary { background: var(--accent); color: #0a0e10; box-shadow: 0 10px 34px -14px rgba(212, 255, 79, 0.65); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 16px 40px -14px rgba(212, 255, 79, 0.8); }
.btn-ghost { border-color: var(--line-strong); color: var(--text); background: rgba(255, 255, 255, 0.02); }
.btn-ghost:hover { border-color: var(--accent); background: var(--accent-soft); }
.btn-sm { padding: 9px 18px; font-size: 0.85rem; }
.btn-block { width: 100%; }

/* ---------- hero ---------- */
.hero { position: relative; overflow: hidden; padding: clamp(72px, 11vw, 138px) 0 var(--section); }
.hero-glow {
  position: absolute; inset: -20% -10% auto; height: 780px; pointer-events: none;
  background:
    radial-gradient(46% 42% at 22% 30%, rgba(212, 255, 79, 0.16), transparent 70%),
    radial-gradient(40% 40% at 78% 18%, rgba(124, 245, 200, 0.12), transparent 72%),
    radial-gradient(52% 50% at 50% 0%, rgba(40, 70, 90, 0.35), transparent 75%);
  filter: blur(8px);
}
.hero::after {
  content: ""; position: absolute; inset: 0; pointer-events: none; opacity: 0.55;
  background-image: linear-gradient(rgba(255, 255, 255, 0.028) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.028) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(60% 55% at 50% 30%, #000 20%, transparent 78%);
  -webkit-mask-image: radial-gradient(60% 55% at 50% 30%, #000 20%, transparent 78%);
}
.hero-inner { position: relative; z-index: 1; max-width: 900px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 0.82rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted);
  border: 1px solid var(--line); background: rgba(255, 255, 255, 0.02);
  padding: 8px 16px; border-radius: 999px; margin-bottom: 26px;
}
.dot { width: 7px; height: 7px; border-radius: 50%; background: var(--mint); box-shadow: 0 0 12px var(--mint); }
h1 em { font-style: normal; color: var(--accent); }
.lede { font-size: clamp(1.05rem, 1.5vw, 1.22rem); color: var(--muted); max-width: 640px; margin: 22px 0 34px; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; }
.hero-points { display: flex; flex-wrap: wrap; gap: 8px 22px; list-style: none; margin: 26px 0 0; padding: 0; color: var(--dim); font-size: 0.9rem; }
.hero-points li::before { content: "✓"; color: var(--accent); margin-right: 8px; font-weight: 700; }
.stats {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1px;
  margin: 54px 0 0; background: var(--line); border: 1px solid var(--line);
  border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow);
}
.stats > div { background: linear-gradient(180deg, rgba(255, 255, 255, 0.035), rgba(255, 255, 255, 0.008)); padding: 20px 22px; }
.stats dt { color: var(--dim); font-size: 0.78rem; letter-spacing: 0.05em; text-transform: uppercase; margin-bottom: 6px; }
.stats dd { margin: 0; font-size: clamp(1.5rem, 2.6vw, 2rem); font-weight: 640; letter-spacing: -0.03em; color: var(--text); }
.stats dd span { font-size: 0.9rem; color: var(--accent); margin-left: 3px; letter-spacing: 0; }

/* ---------- sections ---------- */
.section { padding: var(--section) 0; border-top: 1px solid var(--line); }
section[id] { scroll-margin-top: 84px; }
.section-head { max-width: 720px; margin-bottom: 48px; }
.kicker { color: var(--accent); font-size: 0.8rem; letter-spacing: 0.1em; text-transform: uppercase; margin: 0 0 14px; font-weight: 600; }
.section-head .sub, .sub { color: var(--muted); font-size: 1.02rem; margin: 0; }
.fine { color: var(--dim); font-size: 0.9rem; }

/* ---------- cards ---------- */
.grid { display: grid; gap: 18px; }
.cards { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.035), rgba(255, 255, 255, 0.012));
  border: 1px solid var(--line); border-radius: var(--radius); padding: 26px;
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}
.card:hover { transform: translateY(-4px); border-color: var(--line-strong); background: linear-gradient(180deg, rgba(212, 255, 79, 0.06), rgba(255, 255, 255, 0.015)); }
.card p { color: var(--muted); font-size: 0.94rem; margin-bottom: 14px; }
.card .icon {
  width: 42px; height: 42px; border-radius: 11px; display: grid; place-items: center;
  color: var(--accent); background: var(--accent-soft); border: 1px solid rgba(212, 255, 79, 0.24); margin-bottom: 18px;
}
.card .icon svg { width: 22px; height: 22px; }
.tag { color: var(--dim); font-size: 0.76rem; letter-spacing: 0.03em; margin: 0; font-variant-numeric: tabular-nums; }
a.card { text-decoration: none; color: inherit; display: flex; flex-direction: column; }
a.card .tag { color: var(--accent); font-size: 0.82rem; font-weight: 600; margin-top: auto; padding-top: 6px; }
a.card:hover .tag { text-decoration: underline; }

/* ---------- roi ---------- */
.roi { background: linear-gradient(180deg, var(--bg), var(--bg-soft)); }
.roi-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: clamp(32px, 6vw, 72px); align-items: center; }
.calc {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 10px; box-shadow: var(--shadow);
}
.calc-row { display: flex; justify-content: space-between; align-items: baseline; padding: 15px 18px; border-bottom: 1px solid var(--line); font-size: 0.94rem; color: var(--muted); }
.calc-row strong { color: var(--text); font-size: 1.05rem; font-weight: 600; font-variant-numeric: tabular-nums; }
.calc-row.total { border-bottom: 0; background: var(--accent-soft); border-radius: var(--radius-sm); margin: 6px; padding: 18px; }
.calc-row.total strong { color: var(--accent); font-size: 1.3rem; }
.calc-note { color: var(--dim); font-size: 0.8rem; margin: 12px 18px 12px; }

/* ---------- pricing ---------- */
.pricing-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); align-items: stretch; }
.plan {
  display: flex; flex-direction: column; position: relative;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px 24px;
}
.plan.featured { border-color: rgba(212, 255, 79, 0.55); background: linear-gradient(180deg, rgba(212, 255, 79, 0.08), rgba(255, 255, 255, 0.015) 40%); box-shadow: 0 30px 70px -40px rgba(212, 255, 79, 0.55); }
.plan-badge {
  position: absolute; top: -12px; left: 24px; background: var(--accent); color: #0a0e10;
  font-size: 0.7rem; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase;
  padding: 5px 12px; border-radius: 999px;
}
.plan header { margin-bottom: 18px; }
.plan h3 { font-size: 1.05rem; margin-bottom: 8px; }
.plan-desc { color: var(--muted); font-size: 0.86rem; min-height: 60px; margin-bottom: 18px; }
.price { margin: 0; font-size: 2rem; font-weight: 660; letter-spacing: -0.03em; }
.price small { font-size: 0.8rem; color: var(--dim); font-weight: 400; margin-left: 6px; letter-spacing: 0; }
.price-cn { color: var(--accent); font-size: 0.82rem; margin: 2px 0 0; }
.plan ul { list-style: none; padding: 0; margin: 20px 0 26px; display: grid; gap: 10px; }
.plan li { color: var(--muted); font-size: 0.88rem; padding-left: 22px; position: relative; }
.plan li::before { content: ""; position: absolute; left: 0; top: 0.55em; width: 9px; height: 9px; border-radius: 3px; background: var(--accent-soft); border: 1px solid rgba(212, 255, 79, 0.5); }
.plan .btn { margin-top: auto; }
.plan-care .price { color: var(--mint); }
.pricing-note { color: var(--dim); font-size: 0.86rem; margin-top: 22px; }

/* ---------- process ---------- */
.steps { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 18px; counter-reset: step; }
.steps li { border-top: 1px solid var(--line-strong); padding-top: 22px; }
.step-no { display: block; color: var(--accent); font-variant-numeric: tabular-nums; font-size: 0.82rem; letter-spacing: 0.1em; margin-bottom: 12px; }
.steps h3 { font-size: 1.02rem; }
.steps p { color: var(--muted); font-size: 0.9rem; margin: 0; }

/* ---------- trust ---------- */
.trust { background: var(--bg-soft); }
.trust-inner { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: clamp(32px, 6vw, 72px); }
.checks { list-style: none; padding: 0; margin: 26px 0 0; display: grid; gap: 12px; }
.checks li { position: relative; padding-left: 28px; color: var(--text); font-size: 0.93rem; }
.checks li::before { content: "✓"; position: absolute; left: 0; top: 0; color: var(--accent); font-weight: 700; }
.trust-stack { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; }
.stack-label { color: var(--dim); font-size: 0.76rem; letter-spacing: 0.1em; text-transform: uppercase; margin-bottom: 14px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 26px; }
.chips span { border: 1px solid var(--line-strong); border-radius: 999px; padding: 6px 12px; font-size: 0.78rem; color: var(--muted); }
.infra p:last-child { color: var(--muted); font-size: 0.9rem; margin: 0; }
.infra .stack-label { margin-bottom: 8px; }

/* ---------- faq ---------- */
.faq-wrap { max-width: 900px; }
details { border-bottom: 1px solid var(--line); padding: 20px 0; }
details summary {
  cursor: pointer; list-style: none; font-weight: 560; font-size: 1.02rem;
  display: flex; justify-content: space-between; align-items: center; gap: 20px;
}
details summary::-webkit-details-marker { display: none; }
details summary::after { content: "+"; color: var(--accent); font-size: 1.4rem; line-height: 1; flex: none; }
details[open] summary::after { content: "−"; }
details p { color: var(--muted); font-size: 0.94rem; margin: 14px 0 0; max-width: 760px; }

/* ---------- contact ---------- */
.contact { background: linear-gradient(180deg, var(--bg-soft), var(--bg)); }
.contact-inner { display: grid; grid-template-columns: 0.95fr 1.05fr; gap: clamp(36px, 6vw, 80px); align-items: start; }
.contact-meta { margin-top: 28px; color: var(--muted); font-size: 0.92rem; }
.contact-meta a { color: var(--accent); border-bottom: 1px solid rgba(212, 255, 79, 0.4); }
.form { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: clamp(22px, 3vw, 32px); box-shadow: var(--shadow); }
.field { margin-bottom: 16px; }
.field.row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.field.row > div { display: flex; flex-direction: column; }
label { display: block; font-size: 0.82rem; color: var(--muted); margin-bottom: 7px; letter-spacing: 0.01em; }
input, textarea, select {
  width: 100%; font: inherit; font-size: 0.94rem; color: var(--text);
  background: var(--bg); border: 1px solid var(--line-strong); border-radius: var(--radius-sm);
  padding: 12px 14px; outline: none; transition: border-color 0.16s ease, box-shadow 0.16s ease;
}
input::placeholder, textarea::placeholder { color: var(--dim); }
input:focus, textarea:focus, select:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(212, 255, 79, 0.14); }
textarea { resize: vertical; min-height: 110px; }
select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--dim) 50%), linear-gradient(135deg, var(--dim) 50%, transparent 50%); background-position: calc(100% - 18px) 52%, calc(100% - 13px) 52%; background-size: 5px 5px; background-repeat: no-repeat; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.consent { display: flex; gap: 10px; align-items: flex-start; font-size: 0.82rem; color: var(--muted); margin: 4px 0 18px; }
.consent input { width: 16px; height: 16px; margin-top: 2px; accent-color: var(--accent); flex: none; }
.form-note { margin: 14px 0 0; font-size: 0.88rem; min-height: 20px; color: var(--mint); }
.form-note.error { color: #ff8a8a; }
.form-fine { color: var(--dim); font-size: 0.74rem; margin: 8px 0 0; }

/* ---------- footer ---------- */
.footer { border-top: 1px solid var(--line); padding: 56px 0 28px; background: var(--bg); }
.footer-inner { display: flex; justify-content: space-between; gap: 40px; flex-wrap: wrap; }
.footer-note { color: var(--dim); font-size: 0.82rem; max-width: 380px; margin: 16px 0 0; }
.footer-cols { display: flex; gap: 64px; }
.footer-h { color: var(--dim); font-size: 0.74rem; letter-spacing: 0.1em; text-transform: uppercase; margin: 0 0 12px; }
.footer-cols a { display: block; color: var(--muted); font-size: 0.88rem; margin-bottom: 8px; }
.footer-cols a:hover { color: var(--accent); }
.footer-bottom { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; color: var(--dim); font-size: 0.78rem; border-top: 1px solid var(--line); margin-top: 40px; padding-top: 22px; }

/* ---------- motion ---------- */
@media (prefers-reduced-motion: no-preference) {
  .hero-inner > * { animation: rise 0.7s cubic-bezier(0.2, 0.7, 0.2, 1) both; }
  .hero-inner > :nth-child(1) { animation-delay: 0.02s; }
  .hero-inner > :nth-child(2) { animation-delay: 0.08s; }
  .hero-inner > :nth-child(3) { animation-delay: 0.14s; }
  .hero-inner > :nth-child(4) { animation-delay: 0.2s; }
  .hero-inner > :nth-child(5) { animation-delay: 0.26s; }
  .hero-inner > :nth-child(6) { animation-delay: 0.32s; }
  @keyframes rise { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }
}

/* ---------- responsive ---------- */
@media (max-width: 1040px) {
  .pricing-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .plan-desc { min-height: 0; }
}
@media (max-width: 960px) {
  .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .roi-inner, .trust-inner, .contact-inner { grid-template-columns: 1fr; }
  .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 520px) {
  .nav-actions .btn { display: none; }
}
@media (max-width: 700px) {
  .nav-links { display: none; }
  .nav-actions { margin-left: auto; }
  .cards, .steps, .field.row { grid-template-columns: 1fr; }
  .pricing-grid { grid-template-columns: 1fr; }
  .hero-cta .btn { width: 100%; }
  .footer-cols { gap: 40px; }
  .hero { padding-top: 56px; }
  .stats { margin-top: 36px; }
}