/* ============================================================
   ModelKey 落地页样式 —— 三色克制（白/黑/紫），token 驱动
   权威：ModelKey统一色彩系统 v1.0 §3.1 + 落地页需求 V2.3 §4
   ============================================================ */

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: Inter, -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--mk-bg);
  color: var(--mk-text);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 32px; }

/* 焦点环：紫色唯一允许出现在按钮上的位置 */
:focus-visible { outline: 2px solid var(--mk-accent); outline-offset: 2px; }

/* ---------- 顶部导航（固定吸顶，毛玻璃，无阴影） ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  height: 64px;
  background: rgba(255,255,255,.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--mk-border);
}
.nav-inner { height: 64px; display: flex; align-items: center; justify-content: space-between; }
.nav-brand { display: flex; align-items: center; gap: 10px; }
.nav-brand img { width: 32px; height: 32px; object-fit: contain; }
.nav-brand span { font-size: 20px; font-weight: 500; }
.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a { font-size: 14px; color: var(--mk-text-secondary); transition: color var(--mk-transition); }
.nav-links a:hover { color: var(--mk-text); }
.nav-cta { display: inline-flex; align-items: center; height: 40px; padding: 0 20px; border-radius: var(--mk-radius); background: var(--mk-btn-bg); color: var(--mk-btn-fg); font-size: 14px; font-weight: 600; transition: background var(--mk-transition); }
.nav-cta:hover { background: var(--mk-btn-bg-hover); }
.nav-burger { display: none; background: none; border: none; cursor: pointer; padding: 8px; }

/* ---------- 区块通用 ---------- */
.section { padding: 112px 0; }
.section-head { text-align: center; margin-bottom: 64px; }
.section-head h2 { font-size: clamp(28px, 4vw, 36px); line-height: 1.2; font-weight: 700; }
.section-head p { margin-top: 16px; color: var(--mk-text-secondary); font-size: 17px; }

/* ---------- 区一 Hero ---------- */
.hero { padding: 96px 0 112px; }
.hero-inner { display: grid; grid-template-columns: 1.1fr .9fr; gap: 64px; align-items: center; }
.hero-title { font-size: clamp(32px, 6vw, 56px); line-height: 1.1; font-weight: 700; letter-spacing: -.02em; }
.hero-title .purple { color: var(--mk-accent); }
.hero-sub { margin-top: 24px; font-size: 18px; line-height: 1.6; color: var(--mk-text-secondary); max-width: 560px; }
.hero-actions { margin-top: 40px; display: flex; flex-direction: column; align-items: flex-start; gap: 16px; }
.hero-cta {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 240px; height: 56px; padding: 0 36px;
  border-radius: var(--mk-radius); background: var(--mk-btn-bg); color: var(--mk-btn-fg);
  font-size: 16px; font-weight: 600; transition: background var(--mk-transition), opacity var(--mk-transition);
}
.hero-cta:hover { background: var(--mk-btn-bg-hover); }
.hero-alt { font-size: 14px; color: var(--mk-text-tertiary); }
.hero-alt a { color: var(--mk-accent); }
.hero-alt a:hover { text-decoration: underline; }
.hero-trust { margin-top: 40px; display: flex; flex-wrap: wrap; gap: 24px; color: var(--mk-text-secondary); font-size: 14px; }
.hero-trust span b { color: var(--mk-text); font-weight: 600; }
.hero-visual {
  background: var(--mk-surface-2); border: 1px solid var(--mk-border); border-radius: var(--mk-radius-lg);
  padding: 24px; display: flex; align-items: center; justify-content: center; min-height: 360px;
  color: var(--mk-text-tertiary); font-size: 14px;
}
.hero-visual .mock { width: 100%; }
.mock-line { height: 12px; border-radius: 6px; background: var(--mk-border); margin-bottom: 10px; }
.mock-line.w60 { width: 60%; } .mock-line.w80 { width: 80%; } .mock-line.w40 { width: 40%; }
.mock-chip { display: inline-block; padding: 4px 12px; border-radius: var(--mk-radius-sm); border: 1px solid var(--mk-border); color: var(--mk-accent); font-size: 13px; font-weight: 500; margin-bottom: 16px; }

/* ---------- 区二 核心特性 ---------- */
.features-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature-card { border: 1px solid var(--mk-border); border-radius: var(--mk-radius-lg); padding: 28px; transition: border-color var(--mk-transition); }
.feature-card:hover { border-color: var(--mk-border-strong); }
.feature-icon { width: 40px; height: 40px; border-radius: var(--mk-radius); background: var(--mk-surface-2); display: flex; align-items: center; justify-content: center; margin-bottom: 20px; }
.feature-icon svg { width: 20px; height: 20px; stroke: var(--mk-accent); }
.feature-card h3 { font-size: 20px; font-weight: 600; line-height: 1.4; }
.feature-card p { margin-top: 10px; font-size: 15px; color: var(--mk-text-secondary); line-height: 1.6; }
.feature-data { margin-top: 16px; font-size: 13px; color: var(--mk-text-tertiary); }
.feature-data b { color: var(--mk-accent); font-weight: 600; }

/* ---------- 区三 一键接入演示 ---------- */
.integrate-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.integrate-item { border: 1px solid var(--mk-border); border-radius: var(--mk-radius-lg); padding: 24px; cursor: default; transition: border-color var(--mk-transition); }
.integrate-item:hover, .integrate-item.active { border-color: var(--mk-accent); }
.integrate-logo { width: 44px; height: 44px; border-radius: var(--mk-radius); background: var(--mk-surface-2); display: flex; align-items: center; justify-content: center; margin-bottom: 14px; font-weight: 700; color: var(--mk-text); }
.integrate-item h3 { font-size: 16px; font-weight: 600; }
.integrate-steps { margin-top: 14px; list-style: none; }
.integrate-steps li { font-size: 13px; color: var(--mk-text-secondary); padding: 4px 0; position: relative; padding-left: 20px; }
.integrate-steps li::before { content: ''; position: absolute; left: 0; top: 11px; width: 8px; height: 2px; background: var(--mk-accent); }
.integrate-steps li b { color: var(--mk-text); font-weight: 600; }

/* ---------- 区四 价格 ---------- */
.pricing-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.price-card { position: relative; border: 1px solid var(--mk-border); border-radius: var(--mk-radius-lg); padding: 32px 28px; display: flex; flex-direction: column; }
.price-card.featured { border-color: var(--mk-accent); }
.price-badge { position: absolute; top: -1px; right: 20px; transform: translateY(-50%); padding: 2px 8px; border-radius: 4px; border: 1px solid var(--mk-accent); color: var(--mk-accent); font-size: 12px; font-weight: 500; background: var(--mk-bg); }
.price-card h3 { font-size: 18px; font-weight: 600; }
.price-amount { margin-top: 20px; font-size: 34px; font-weight: 700; line-height: 1; }
.price-amount .cur { color: var(--mk-accent); }
.price-amount .unit { font-size: 14px; color: var(--mk-text-tertiary); font-weight: 400; }
.price-features { margin-top: 24px; list-style: none; flex: 1; }
.price-features li { font-size: 14px; color: var(--mk-text-secondary); padding: 7px 0; position: relative; padding-left: 20px; }
.price-features li::before { content: ''; position: absolute; left: 0; top: 15px; width: 8px; height: 8px; border-radius: 50%; background: var(--mk-surface-2); }
.price-features li.on::before { background: var(--mk-accent); }
.price-card .btn { margin-top: 28px; }
.price-note { margin-top: 24px; text-align: center; font-size: 14px; color: var(--mk-text-tertiary); }

/* ---------- 区五 FAQ ---------- */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { border-bottom: 1px solid var(--mk-border); }
.faq-q { width: 100%; text-align: left; background: none; border: none; cursor: pointer; padding: 24px 0; font-size: 16px; font-weight: 600; color: var(--mk-text); display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.faq-q .icon { flex-shrink: 0; width: 20px; height: 20px; color: var(--mk-text-tertiary); transition: transform var(--mk-transition); }
.faq-item.open .faq-q .icon { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .2s ease-out; }
.faq-a-inner { padding: 0 0 24px; color: var(--mk-text-secondary); font-size: 15px; }

/* ---------- 区六 下载双按钮 ---------- */
.download-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; max-width: 760px; margin: 0 auto; }
.download-card { border: 1px solid var(--mk-border); border-radius: var(--mk-radius-lg); padding: 32px; text-align: center; }
.download-card h3 { font-size: 18px; font-weight: 600; }
.download-card .meta { margin: 12px 0 24px; font-size: 13px; color: var(--mk-text-tertiary); }
.download-card .btn { width: 100%; height: 48px; display: inline-flex; align-items: center; justify-content: center; border-radius: var(--mk-radius); font-weight: 600; transition: background var(--mk-transition), border-color var(--mk-transition); }
.btn-primary { background: var(--mk-btn-bg); color: var(--mk-btn-fg); }
.btn-primary:hover { background: var(--mk-btn-bg-hover); }
.btn-secondary { background: var(--mk-bg); color: var(--mk-text); border: 1px solid var(--mk-btn2-border); }
.btn-secondary:hover { border-color: var(--mk-text); }

/* ---------- 区七 Footer（纯黑） ---------- */
.footer { background: #0A0A0B; color: #F2F2F5; padding: 64px 0 40px; }
.footer-inner { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 48px; }
.footer-brand { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; }
.footer-brand img { width: 28px; height: 28px; object-fit: contain; }
.footer-brand span { font-size: 16px; font-weight: 500; }
.footer-brand-tag { color: #A0A0AA; font-size: 14px; max-width: 320px; }
.footer h4 { font-size: 14px; font-weight: 600; margin-bottom: 16px; color: #F2F2F5; }
.footer a { display: block; color: #A0A0AA; font-size: 14px; padding: 6px 0; transition: color .2s; }
.footer a:hover { color: #F2F2F5; }
.footer-bottom { margin-top: 48px; padding-top: 24px; border-top: 1px solid #26262C; display: flex; flex-wrap: wrap; gap: 12px; justify-content: space-between; color: #6E6E78; font-size: 13px; }

/* ---------- 按钮通用（无阴影、无位移，仅颜色过渡） ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 14px 32px; border-radius: var(--mk-radius); font-size: 16px; font-weight: 600; border: 1px solid transparent; transition: background var(--mk-transition), border-color var(--mk-transition), color var(--mk-transition); cursor: pointer; }
.btn:disabled { opacity: .4; cursor: not-allowed; }

/* ---------- 移动端复制链接 ---------- */
.qr-wrap { display: none; margin-top: 16px; }
.qr-wrap.show { display: block; }

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .pricing-grid { grid-template-columns: repeat(2, 1fr); }
  .integrate-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .section { padding: 56px 0; }
  .container { padding: 0 24px; }
  .nav-links { display: none; }
  .nav-burger { display: block; }
  .nav-links.open { display: flex; flex-direction: column; position: absolute; top: 64px; left: 0; right: 0; background: var(--mk-bg); border-bottom: 1px solid var(--mk-border); padding: 16px 24px; gap: 16px; }
  .hero { padding: 48px 0 64px; }
  .hero-inner { grid-template-columns: 1fr; gap: 40px; }
  .hero-visual { min-height: 240px; }
  .hero-cta { width: 100%; }
  .features-grid { grid-template-columns: 1fr; }
  .integrate-grid { grid-template-columns: 1fr 1fr; }
  .pricing-grid { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; gap: 32px; }
}
@media (hover: hover) {
  /* 触控设备禁用 hover 动效 */
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
  html { scroll-behavior: auto; }
}