/* ===========================================================
   SIP电话助手 · 宣传站样式
   苹果风 / 蓝白医疗色调 / 磨砂导航 / 滚动渐显
   =========================================================== */

:root {
  --blue: #0a6cff;
  --blue-dark: #084fcc;
  --blue-deep: #0536a8;
  --ink: #1d1d1f;
  --ink-2: #6e6e73;
  --ink-3: #86868b;
  --bg: #ffffff;
  --bg-soft: #f5f7fb;
  --bg-tint: #eaf1ff;
  --line: #e6e9ef;
  --radius: 20px;
  --radius-sm: 14px;
  --maxw: 1120px;
  --maxw-text: 740px;
  --nav-h: 56px;
  --shadow-sm: 0 2px 10px rgba(10, 60, 160, .06);
  --shadow-md: 0 18px 50px rgba(10, 60, 160, .12);
  --shadow-lg: 0 30px 80px rgba(10, 60, 160, .16);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + 12px); }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.wrap-text { max-width: var(--maxw-text); margin: 0 auto; padding: 0 24px; }

/* ---------- 导航 ---------- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; height: var(--nav-h);
  z-index: 100;
  background: rgba(255, 255, 255, .72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, .06);
}
.nav-inner {
  max-width: var(--maxw); margin: 0 auto; height: 100%;
  padding: 0 24px; display: flex; align-items: center; justify-content: space-between;
}
.brand { display: flex; align-items: center; font-weight: 600; font-size: 17px; letter-spacing: .2px; }
.brand img { width: 28px; height: 28px; border-radius: 7px; margin-right: 10px; }
.brand .en { color: var(--ink-3); font-weight: 500; font-size: 14px; }

.nav-links { display: flex; align-items: center; }
.nav-links a { font-size: 14px; color: var(--ink-2); transition: color .2s; margin-right: 30px; }
.nav-links a:last-child { margin-right: 0; }
.nav-links a:hover { color: var(--ink); }
.btn-pill {
  background: var(--blue); color: #fff; padding: 7px 16px; border-radius: 980px;
  font-size: 14px; font-weight: 500; transition: background .2s, transform .2s;
}
.btn-pill:hover { background: var(--blue-dark); transform: translateY(-1px); }
/* 导航胶囊按钮文字强制白色：否则会被 .nav-links a 的灰色（--ink-2）覆盖，看起来像黑字 */
.nav-links a.btn-pill,
.nav-links a.btn-pill:hover { color: #fff; }

.nav-toggle { display: none; background: none; border: 0; cursor: pointer; width: 40px; height: 40px; }
.nav-toggle span { display: block; width: 20px; height: 2px; background: var(--ink); margin: 4px auto; transition: .3s; }

/* ---------- 通用区块 ---------- */
section { padding: 96px 0; }
.section-soft { background: var(--bg-soft); }
.eyebrow {
  font-size: 13px; font-weight: 600; letter-spacing: 1.5px; text-transform: uppercase;
  color: var(--blue); margin-bottom: 14px;
}
.h2 { font-size: clamp(30px, 4.4vw, 46px); font-weight: 700; letter-spacing: -.5px; line-height: 1.12; }
.h3 { font-size: clamp(22px, 3vw, 30px); font-weight: 650; letter-spacing: -.3px; }
.lead { font-size: 19px; color: var(--ink-2); margin-top: 18px; }
#help .lead { margin-bottom: 8px; }
.help-cta { margin-top: 24px; display: inline-block; }
.center { text-align: center; }

/* ---------- Hero ---------- */
.hero {
  padding: calc(var(--nav-h) + 70px) 0 60px;
  text-align: center;
  background:
    radial-gradient(1200px 520px at 50% -10%, rgba(10, 108, 255, .14), transparent 60%),
    linear-gradient(180deg, #f3f8ff 0%, #ffffff 70%);
}
.hero .badge {
  display: inline-flex; align-items: center; font-size: 13px; color: var(--blue-dark);
  background: #fff; border: 1px solid rgba(10, 108, 255, .25); padding: 6px 14px; border-radius: 980px;
  box-shadow: var(--shadow-sm); margin-bottom: 26px;
}
.hero h1 { font-size: clamp(44px, 7vw, 78px); font-weight: 700; letter-spacing: -1.5px; line-height: 1.02; }
.hero .grad {
  background: linear-gradient(100deg, var(--blue) 0%, var(--blue-deep) 60%, #7a3cff 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero .sub { font-size: clamp(19px, 2.4vw, 25px); color: var(--ink-2); margin-top: 18px; font-weight: 500; }
.hero .cta { margin-top: 34px; display: flex; justify-content: center; flex-wrap: wrap; }
.hero .cta > a:not(:last-child) { margin-right: 16px; }
.btn-primary {
  background: var(--blue); color: #fff; padding: 13px 30px; border-radius: 980px;
  font-size: 17px; font-weight: 500; transition: .2s; box-shadow: 0 10px 30px rgba(10, 108, 255, .3);
}
.btn-primary:hover { background: var(--blue-dark); transform: translateY(-2px); }
.btn-ghost { color: var(--blue); padding: 13px 26px; border-radius: 980px; font-size: 17px; font-weight: 500; }
.btn-ghost:hover { text-decoration: underline; }

.hero-shot {
  margin: 56px auto 0; max-width: 1000px; border-radius: 22px; overflow: hidden;
  box-shadow: var(--shadow-lg); border: 1px solid rgba(255, 255, 255, .6);
}
.hero-shot img { width: 100%; }

/* 子页面紧凑 Hero（帮助页等，不显示大截图与 CTA） */
.hero.compact { padding: calc(var(--nav-h) + 46px) 0 34px; }
.hero.compact h1 { font-size: clamp(34px, 5vw, 52px); }
.hero.compact .sub { font-size: 20px; }
.hero.compact .cta, .hero.compact .hero-shot { display: none; }

/* ---------- 卖点卡片 ---------- */
.points { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; margin-top: 54px; }
.point {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 26px;
  box-shadow: var(--shadow-sm); transition: transform .25s, box-shadow .25s;
}
.point:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.point .ico { font-size: 30px; }
.point h4 { font-size: 18px; font-weight: 650; margin: 12px 0 8px; }
.point p { color: var(--ink-2); font-size: 15px; }

/* ---------- 功能交替行 ---------- */
.feature-row {
  display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center;
  max-width: var(--maxw); margin: 0 auto; padding: 56px 24px;
}
.feature-row.reverse .f-media { order: 2; }
.feature-row .f-text .tag { color: var(--blue); font-weight: 600; font-size: 14px; letter-spacing: .5px; }
.feature-row .f-text h3 { margin: 10px 0 16px; }
.feature-row .f-text ul { list-style: none; }
.feature-row .f-text li {
  position: relative; padding-left: 26px; margin: 11px 0; color: var(--ink-2); font-size: 16px;
}
.feature-row .f-text li::before {
  content: ""; position: absolute; left: 0; top: 9px; width: 14px; height: 14px;
  border-radius: 50%; background: var(--bg-tint);
  box-shadow: inset 0 0 0 4px var(--blue);
}
.f-media img {
  width: 100%; border-radius: var(--radius); border: 1px solid var(--line);
  box-shadow: var(--shadow-md); background: #fff;
}

/* ---------- 技术架构 ---------- */
.arch {
  max-width: 860px; margin: 44px auto 0; border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow-md); border: 1px solid var(--line);
}
.arch .layer { padding: 22px 26px; border-bottom: 1px solid var(--line); }
.arch .layer:last-child { border-bottom: 0; }
.arch .layer.l1 { background: linear-gradient(100deg, #eaf1ff, #f5f8ff); }
.arch .layer.l2 { background: #fff; }
.arch .layer.l3 { background: var(--bg-soft); }
.arch .lt { font-size: 13px; font-weight: 700; letter-spacing: 1px; color: var(--blue-dark); text-transform: uppercase; }
.arch .ld { margin-top: 6px; font-size: 15px; color: var(--ink-2); }
.cards-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; margin-top: 40px; }
.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px;
  box-shadow: var(--shadow-sm);
}
.card h4 { font-size: 17px; font-weight: 650; margin-bottom: 10px; }
.card p { color: var(--ink-2); font-size: 15px; }

/* ---------- 优势分类 ---------- */
.adv-group { margin-top: 40px; }
.adv-group h3 { font-size: 20px; font-weight: 650; margin-bottom: 18px; display: flex; align-items: center; }
.adv-group h3 .dot { width: 10px; height: 10px; border-radius: 50%; background: var(--blue); margin-right: 10px; }
.adv-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px 28px; }
.adv-list li { list-style: none; padding-left: 24px; position: relative; color: var(--ink-2); font-size: 16px; }
.adv-list li::before {
  content: "✓"; position: absolute; left: 0; top: 0; color: var(--blue); font-weight: 700;
}

/* ---------- 下载 ---------- */
.dl-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; margin-top: 46px; }
.dl-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 26px;
  box-shadow: var(--shadow-sm); text-align: center; transition: transform .25s, box-shadow .25s;
  display: flex; flex-direction: column;
}
.dl-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.dl-card .os { font-size: 19px; font-weight: 650; }
.dl-card .meta { color: var(--ink-3); font-size: 14px; margin: 6px 0 18px; }
.dl-card .feat { color: var(--ink-2); font-size: 14px; min-height: 60px; }
.dl-card .btn-primary, .dl-card .btn-ghost { margin-top: auto; display: inline-block; }
.dl-actions { display: flex; margin-top: auto; justify-content: center; width: 100%; }
.dl-actions > a:not(:last-child) { margin-right: 10px; }
.dl-actions .btn-primary, .dl-actions .btn-ghost { flex: none; width: calc(50% - 5px); padding: 11px 0; font-size: 15px; text-align: center; }
.dl-note { margin-top: 30px; font-size: 14px; color: var(--ink-3); text-align: center; }
.variant-table { max-width: 920px; margin: 40px auto 0; border-collapse: collapse; width: 100%; font-size: 15px; }
.variant-table th, .variant-table td { border: 1px solid var(--line); padding: 14px 16px; text-align: left; }
.variant-table th { background: var(--bg-tint); color: var(--blue-dark); font-weight: 650; }
.variant-table td code { background: var(--bg-soft); padding: 2px 6px; border-radius: 6px; font-size: 13px; }

/* ---------- 帮助 / FAQ ---------- */
.faq { max-width: 820px; margin: 40px auto 0; }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-q {
  width: 100%; text-align: left; background: none; border: 0; cursor: pointer;
  padding: 22px 0; font-size: 18px; font-weight: 600; color: var(--ink);
  display: flex; justify-content: space-between; align-items: center;
}
.faq-q .sign { color: var(--blue); font-size: 24px; transition: transform .25s; flex: none; margin-left: 16px; }
.faq-item.open .faq-q .sign { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .35s ease; color: var(--ink-2); font-size: 16px; }
.faq-a p { padding: 0 0 22px; }
.steps { max-width: 1000px; margin: 36px auto 0; counter-reset: s; }
.step { display: flex; padding: 16px 0; align-items: center; }
.step .num {
  counter-increment: s; flex: none; width: 34px; height: 34px; border-radius: 50%;
  background: var(--blue); color: #fff; font-weight: 700; display: grid; place-items: center; font-size: 15px;
  margin-right: 18px;
}
.step .num::before { content: counter(s); }
.step .st { font-size: 16px; color: var(--ink-2); text-align: left; }
.step .st b { color: var(--ink); font-weight: 600; }

/* ---------- 页脚 ---------- */
.footer { background: var(--bg-soft); border-top: 1px solid var(--line); padding: 56px 0 36px; }
.footer-inner { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; display: flex; flex-wrap: wrap; justify-content: space-between; }
.footer-inner > *:not(:last-child) { margin-right: 30px; }
.footer .f-brand { display: flex; align-items: center; font-weight: 600; }
.footer .f-brand img { width: 30px; height: 30px; border-radius: 7px; margin-right: 10px; }
.footer .f-col h5 { font-size: 14px; color: var(--ink); margin-bottom: 12px; }
.footer .f-col a { display: block; color: var(--ink-2); font-size: 14px; margin: 8px 0; }
.footer .f-col a:hover { color: var(--blue); }
.footer .copy { width: 100%; margin-top: 30px; padding-top: 22px; border-top: 1px solid var(--line); color: var(--ink-3); font-size: 13px; }

/* ---------- 滚动渐显 ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity .7s cubic-bezier(.2,.7,.2,1), transform .7s cubic-bezier(.2,.7,.2,1); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } html { scroll-behavior: auto; } }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .points, .cards-3, .dl-grid { grid-template-columns: 1fr; }
  .adv-list { grid-template-columns: 1fr; }
  .feature-row { grid-template-columns: 1fr; gap: 28px; }
  .feature-row.reverse .f-media { order: 0; }
  section { padding: 70px 0; }
}
@media (max-width: 720px) {
  .nav-links { display: none; }
  .nav-links.show {
    display: flex; position: absolute; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; gap: 0; background: rgba(255,255,255,.96);
    backdrop-filter: blur(20px); padding: 8px 24px 18px; border-bottom: 1px solid var(--line);
  }
  .nav-links.show a { padding: 13px 0; border-bottom: 1px solid var(--line); margin-right: 0; }
  .nav-links.show .btn-pill { margin-top: 12px; text-align: center; }
  .nav-toggle { display: block; }
}