/* =============================================================
   YI CAN TECHNOLOGY LIMITED - corporate site styles
   Single accent (cobalt blue), single radius scale, light theme.
   No external font / image dependencies.
   ============================================================= */

:root {
  /* Neutrals */
  --bg: #fdfdfe;
  --surface: #f4f7fb;
  --surface-2: #eef2f8;
  --ink: #0c1b2a;        /* near-black navy, not pure black */
  --text: #36465a;       /* body */
  --muted: #62748a;      /* secondary */
  --line: #e2e8f1;       /* hairlines / borders */
  --line-strong: #cdd7e4;

  /* Single locked accent */
  --accent: #1f50e0;
  --accent-ink: #163fb0;
  --accent-soft: #eaf0fe;
  --accent-contrast: #ffffff;

  /* One radius scale */
  --radius: 14px;
  --radius-sm: 10px;

  --container: 1180px;
  --shadow: 0 1px 2px rgba(12, 27, 42, .04),
            0 12px 32px -16px rgba(12, 27, 42, .18);
  --shadow-soft: 0 1px 2px rgba(12, 27, 42, .04),
                 0 8px 24px -18px rgba(12, 27, 42, .14);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", sans-serif;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--accent-ink); text-decoration: none; }
a:hover { color: var(--accent); }
h1, h2, h3, h4 { color: var(--ink); margin: 0; line-height: 1.12; letter-spacing: -0.02em; font-weight: 650; }
p { margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation-duration: .001ms !important; transition-duration: .001ms !important; }
}

/* ---------- Layout helpers ---------- */
.container { width: 100%; max-width: var(--container); margin-inline: auto; padding-inline: 24px; }
.section { padding-block: clamp(64px, 9vw, 116px); }
.section--tight { padding-block: clamp(48px, 6vw, 80px); }
.section--surface { background: var(--surface); border-block: 1px solid var(--line); }
.lead { font-size: clamp(18px, 2.2vw, 21px); color: var(--text); max-width: 60ch; }
.measure { max-width: 65ch; }
.eyebrow {
  display: inline-block;
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-ink);
  margin-bottom: 18px;
}
.section-head { max-width: 62ch; margin-bottom: clamp(36px, 5vw, 56px); }
.section-head h2 { font-size: clamp(28px, 4vw, 42px); }
.section-head p { margin-top: 18px; color: var(--muted); font-size: clamp(16px, 1.8vw, 18.5px); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  font-size: 15.5px; font-weight: 600;
  padding: 13px 22px; border-radius: var(--radius-sm);
  border: 1px solid transparent; cursor: pointer;
  transition: transform .15s ease, background .2s ease, border-color .2s ease, box-shadow .2s ease;
  white-space: nowrap;
}
.btn:active { transform: translateY(1px); }
.btn--primary { background: var(--accent); color: var(--accent-contrast); box-shadow: 0 8px 20px -10px rgba(31,80,224,.6); }
.btn--primary:hover { background: var(--accent-ink); color: #fff; }
.btn--ghost { background: #fff; color: var(--ink); border-color: var(--line-strong); }
.btn--ghost:hover { border-color: var(--accent); color: var(--accent-ink); }
.btn--lg { padding: 15px 26px; font-size: 16px; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(253,253,254,.86);
  backdrop-filter: saturate(160%) blur(12px);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 70px; gap: 24px; }
.brand { display: inline-flex; align-items: center; gap: 11px; color: var(--ink); font-weight: 650; letter-spacing: -0.01em; }
.brand:hover { color: var(--ink); }
.brand__mark { width: 30px; height: 30px; flex: 0 0 auto; }
.brand__name { font-size: 16px; line-height: 1.05; }
.brand__name small { display: block; font-size: 10.5px; font-weight: 600; letter-spacing: 0.12em; color: var(--muted); text-transform: uppercase; margin-top: 2px; }
.nav__links { display: flex; align-items: center; gap: 30px; }
.nav__links a { color: var(--text); font-size: 15px; font-weight: 550; }
.nav__links a:hover, .nav__links a[aria-current="page"] { color: var(--ink); }
.nav__links a[aria-current="page"] { position: relative; }
.nav__links a[aria-current="page"]::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -25px; height: 2px; background: var(--accent);
}
.nav__cta { display: flex; align-items: center; gap: 14px; }
.nav__toggle { display: none; }

/* ---------- Hero ---------- */
.hero { position: relative; overflow: hidden; background: var(--bg); }
.hero::before {
  content: ""; position: absolute; inset: 0; z-index: 0; pointer-events: none;
  background:
    radial-gradient(60% 70% at 88% 8%, rgba(31,80,224,.10), transparent 60%),
    radial-gradient(50% 60% at 6% 96%, rgba(31,80,224,.06), transparent 60%);
}
.hero__grid {
  position: relative; z-index: 1;
  display: grid; grid-template-columns: 1.05fr .95fr; gap: clamp(32px, 5vw, 72px);
  align-items: center;
  padding-block: clamp(56px, 8vw, 104px);
}
.hero__title { font-size: clamp(34px, 5.4vw, 60px); letter-spacing: -0.03em; line-height: 1.04; }
.hero__title .accent { color: var(--accent); }
.hero__sub { margin-top: 24px; font-size: clamp(17px, 2vw, 20px); color: var(--text); max-width: 52ch; }
.hero__actions { margin-top: 34px; display: flex; flex-wrap: wrap; gap: 14px; }
.hero__meta { margin-top: 34px; display: flex; flex-wrap: wrap; gap: 28px; color: var(--muted); font-size: 14.5px; }
.hero__meta strong { display: block; color: var(--ink); font-size: 15px; font-weight: 600; }

/* Hero visual: self-contained network/globe motif */
.hero__visual { position: relative; aspect-ratio: 1 / 1; max-width: 480px; margin-inline: auto; width: 100%; }
.hero__panel {
  position: absolute; inset: 0;
  border: 1px solid var(--line); border-radius: 24px;
  background:
    linear-gradient(180deg, #ffffff, #f6f9fe);
  box-shadow: var(--shadow);
  overflow: hidden;
}
.hero__panel svg { width: 100%; height: 100%; }

/* ---------- Capability / feature grid ---------- */
.cap-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.cap {
  background: var(--bg); padding: clamp(26px, 3vw, 38px);
  display: flex; flex-direction: column; gap: 14px;
}
.cap__icon {
  width: 44px; height: 44px; border-radius: 11px;
  display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent-ink);
}
.cap__icon svg { width: 23px; height: 23px; }
.cap h3 { font-size: 20px; }
.cap p { color: var(--muted); font-size: 15.5px; }
.cap__index { font-size: 13px; font-weight: 600; color: var(--accent-ink); letter-spacing: .04em; }

/* ---------- Solutions list (varied layout) ---------- */
.solution { display: grid; grid-template-columns: minmax(0, 360px) 1fr; gap: clamp(24px, 5vw, 64px); padding-block: clamp(40px, 5vw, 60px); border-top: 1px solid var(--line); align-items: start; }
.solution:first-of-type { border-top: 0; }
.solution__label { display: flex; align-items: center; gap: 16px; }
.solution__num { font-size: 14px; font-weight: 600; color: var(--accent-ink); }
.solution__title { font-size: clamp(23px, 3vw, 30px); }
.solution__body p { color: var(--text); }
.solution__body p + p { margin-top: 16px; }
.tag-row { margin-top: 22px; display: flex; flex-wrap: wrap; gap: 10px; }
.tag { font-size: 13.5px; font-weight: 550; color: var(--ink); background: var(--surface); border: 1px solid var(--line); padding: 7px 13px; border-radius: 999px; }

/* ---------- Generic content (about / legal) ---------- */
.prose { max-width: 70ch; }
.prose h2 { font-size: clamp(24px, 3vw, 31px); margin-top: 52px; margin-bottom: 16px; }
.prose h3 { font-size: 19px; margin-top: 34px; margin-bottom: 10px; }
.prose p { margin-top: 14px; color: var(--text); }
.prose ul.bullets { margin-top: 16px; display: grid; gap: 12px; }
.prose ul.bullets li { position: relative; padding-left: 26px; color: var(--text); }
.prose ul.bullets li::before { content: ""; position: absolute; left: 4px; top: 11px; width: 7px; height: 7px; border-radius: 2px; background: var(--accent); }
.prose a { text-decoration: underline; text-underline-offset: 2px; }

/* Principle cards */
.principles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.principle { background: var(--bg); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow-soft); }
.principle h3 { font-size: 18px; margin-bottom: 10px; }
.principle p { color: var(--muted); font-size: 15px; }

/* Stat / fact strip (no fabricated metrics, factual only) */
.facts { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.fact { background: var(--bg); padding: 28px; }
.fact dt { font-size: 13px; font-weight: 600; letter-spacing: .04em; text-transform: uppercase; color: var(--muted); }
.fact dd { margin: 8px 0 0; font-size: 18px; font-weight: 600; color: var(--ink); }

/* ---------- Contact ---------- */
.contact-grid { display: grid; grid-template-columns: 1fr 1.1fr; gap: clamp(32px, 5vw, 64px); align-items: start; }
.contact-cards { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; max-width: 840px; }
@media (max-width: 760px) { .contact-cards { grid-template-columns: 1fr; } }
.info-card { border: 1px solid var(--line); border-radius: var(--radius); padding: 30px; background: var(--bg); box-shadow: var(--shadow-soft); }
.info-card + .info-card { margin-top: 20px; }
.info-card h3 { font-size: 16px; letter-spacing: .02em; }
.info-card p { margin-top: 10px; color: var(--text); }
.info-card a { font-weight: 600; }

.form { display: grid; gap: 18px; border: 1px solid var(--line); border-radius: var(--radius); padding: clamp(24px, 3vw, 34px); background: var(--bg); box-shadow: var(--shadow); }
.field { display: grid; gap: 8px; }
.field label { font-size: 14px; font-weight: 600; color: var(--ink); }
.field input, .field textarea {
  font: inherit; font-size: 15.5px; color: var(--ink);
  padding: 12px 14px; border: 1px solid var(--line-strong); border-radius: var(--radius-sm);
  background: #fff; transition: border-color .2s ease, box-shadow .2s ease;
}
.field input::placeholder, .field textarea::placeholder { color: #93a2b4; }
.field input:focus, .field textarea:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px rgba(31,80,224,.14); }
.field textarea { resize: vertical; min-height: 130px; }
.form__note { font-size: 13.5px; color: var(--muted); }
.form__status { font-size: 14.5px; font-weight: 550; }

/* ---------- Page hero (inner pages) ---------- */
.page-hero { padding-block: clamp(56px, 7vw, 92px) clamp(28px, 4vw, 44px); background: var(--bg); border-bottom: 1px solid var(--line); position: relative; overflow: hidden; }
.page-hero::before { content: ""; position: absolute; inset: 0; background: radial-gradient(45% 80% at 92% 0%, rgba(31,80,224,.07), transparent 60%); pointer-events: none; }
.page-hero__inner { position: relative; }
.page-hero h1 { font-size: clamp(32px, 5vw, 50px); letter-spacing: -0.03em; max-width: 18ch; }
.page-hero p { margin-top: 20px; font-size: clamp(17px, 2vw, 20px); color: var(--text); max-width: 56ch; }

/* ---------- CTA band ---------- */
.cta-band { background: var(--ink); color: #dbe6f3; border-radius: 0; }
.cta-band__inner { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 28px; padding-block: clamp(44px, 6vw, 72px); }
.cta-band h2 { color: #fff; font-size: clamp(24px, 3.4vw, 36px); max-width: 20ch; }
.cta-band p { margin-top: 12px; color: #9fb2c8; max-width: 46ch; }
.cta-band .btn--ghost { background: transparent; color: #fff; border-color: rgba(255,255,255,.28); }
.cta-band .btn--ghost:hover { border-color: #fff; color: #fff; }

/* ---------- Footer ---------- */
.site-footer { background: var(--ink); color: #93a6bd; padding-block: clamp(48px, 6vw, 72px) 32px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 40px; }
.footer-brand { display: inline-flex; align-items: center; gap: 11px; color: #fff; font-weight: 650; margin-bottom: 18px; }
.footer-brand .brand__mark { width: 28px; height: 28px; }
.site-footer address { font-style: normal; line-height: 1.7; font-size: 14.5px; max-width: 34ch; color: #93a6bd; }
.footer-col h4 { color: #cdd9e7; font-size: 13px; letter-spacing: .08em; text-transform: uppercase; margin-bottom: 16px; font-weight: 600; }
.footer-col ul { display: grid; gap: 11px; }
.footer-col a { color: #93a6bd; font-size: 15px; }
.footer-col a:hover { color: #fff; }
.footer-bottom { margin-top: 44px; padding-top: 22px; border-top: 1px solid rgba(255,255,255,.1); display: flex; flex-wrap: wrap; gap: 14px 24px; align-items: center; justify-content: space-between; font-size: 13.5px; }
.footer-bottom a { color: #93a6bd; }
.footer-bottom a:hover { color: #fff; }
.footer-bottom .legal-links { display: flex; gap: 22px; }

/* ---------- Reveal on scroll (progressive, JS-gated) ---------- */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity .6s cubic-bezier(.16,1,.3,1), transform .6s cubic-bezier(.16,1,.3,1); }
.reveal.is-in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; } }

/* ---------- Responsive ---------- */
@media (max-width: 940px) {
  .hero__grid { grid-template-columns: 1fr; }
  .hero__visual { max-width: 380px; order: -1; }
  .principles { grid-template-columns: 1fr; }
  .facts { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 760px) {
  body { font-size: 16.5px; }
  .nav__links, .nav__cta .btn { display: none; }
  .nav__toggle { display: inline-flex; }
  .nav__links.is-open {
    display: flex; position: absolute; left: 0; right: 0; top: 70px;
    flex-direction: column; align-items: flex-start; gap: 4px;
    background: var(--bg); border-bottom: 1px solid var(--line);
    padding: 14px 24px 22px; box-shadow: var(--shadow);
  }
  .nav__links.is-open a { padding: 10px 0; width: 100%; font-size: 16px; }
  .nav__links.is-open a[aria-current="page"]::after { display: none; }
  .cap-grid { grid-template-columns: 1fr; }
  .solution { grid-template-columns: 1fr; gap: 16px; }
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
  .cta-band__inner { flex-direction: column; align-items: flex-start; }
}

/* ---------- Mobile nav toggle button ---------- */
.nav__toggle { background: none; border: 1px solid var(--line-strong); border-radius: 9px; width: 42px; height: 42px; align-items: center; justify-content: center; cursor: pointer; color: var(--ink); }
.nav__toggle svg { width: 22px; height: 22px; }