:root {
  color: #172033;
  background: #f6f8fb;
  font-family: "Noto Sans SC", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* { box-sizing: border-box; }
body { margin: 0; min-width: 320px; }
a { color: inherit; text-decoration: none; }

.site-header,
.site-footer,
main { width: min(1120px, calc(100% - 48px)); margin: 0 auto; }
.site-header { display: flex; align-items: center; justify-content: space-between; padding: 28px 0; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-size: 18px; font-weight: 700; }
.brand img { width: 32px; height: 32px; }
.header-link { color: #4b5b73; font-size: 14px; }
.header-link:hover { color: #1989fa; }

.hero { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(360px, .95fr); gap: 72px; align-items: center; min-height: 560px; padding: 52px 0 72px; }
.eyebrow { margin: 0 0 18px; color: #1989fa; font-size: 12px; font-weight: 800; letter-spacing: 2px; }
h1 { max-width: 620px; margin: 0; color: #101828; font-size: clamp(40px, 6vw, 72px); line-height: 1.12; letter-spacing: 0; }
.hero-text { max-width: 520px; margin: 26px 0 0; color: #58677f; font-size: 18px; line-height: 1.8; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 46px; padding: 0 20px; border-radius: 6px; font-size: 14px; font-weight: 700; transition: transform .2s, box-shadow .2s; }
.button:hover { transform: translateY(-2px); box-shadow: 0 8px 20px rgba(16, 24, 40, .12); }
.button-primary { color: #fff; background: #1989fa; }
.button-secondary { color: #1769b0; background: #e4f1ff; }
.button[aria-disabled="true"] { opacity: .6; pointer-events: none; }
.download-info { color: #68768b; font-size: 13px; line-height: 1.6; }
#download-retry { border: 0; background: none; padding: 0; color: #1769b0; cursor: pointer; }

.hero-visual { display: flex; justify-content: center; }
.visual-window { width: min(100%, 430px); padding: 22px; border: 1px solid #dce5f0; border-radius: 12px; background: #fff; box-shadow: 0 24px 60px rgba(32, 59, 93, .13); }
.visual-topbar { display: flex; gap: 6px; padding-bottom: 26px; border-bottom: 1px solid #edf1f6; }
.visual-topbar span { width: 8px; height: 8px; border-radius: 50%; background: #cbd5e1; }
.visual-chat { max-width: 78%; margin-top: 26px; padding: 13px 15px; border-radius: 9px; font-size: 14px; line-height: 1.5; }
.visual-chat-user { margin-left: auto; color: #fff; background: #1989fa; }
.visual-chat-ai { color: #344054; background: #f0f4f8; }
.visual-line { width: 86%; height: 9px; margin-top: 34px; border-radius: 4px; background: #e9eef5; }
.visual-line.short { width: 58%; margin-top: 12px; }

.feature-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 36px; padding: 34px 0 74px; border-top: 1px solid #dce5f0; }
.feature-row article { min-width: 0; }
.feature-index { color: #1989fa; font-size: 12px; font-weight: 800; }
h2 { margin: 14px 0 10px; color: #172033; font-size: 20px; }
.feature-row p { margin: 0; color: #68768b; font-size: 14px; line-height: 1.8; }
.site-footer { display: flex; justify-content: space-between; padding: 22px 0 30px; border-top: 1px solid #dce5f0; color: #8491a5; font-size: 12px; }

@media (max-width: 760px) {
  .site-header, .site-footer, main { width: min(100% - 32px, 560px); }
  .site-header { padding: 20px 0; }
  .hero { display: block; min-height: auto; padding: 54px 0 62px; }
  h1 { font-size: clamp(38px, 12vw, 56px); }
  .hero-text { font-size: 16px; }
  .hero-visual { margin-top: 48px; }
  .feature-row { grid-template-columns: 1fr; gap: 28px; padding-bottom: 54px; }
}