/* ==========================================================================
   泡泡加速官网样式
   零依赖：不引任何字体 / 图标库 / 框架，系统字体栈 + 手写图标（内联 SVG）。
   浅色单页：白底 + 深蓝墨色正文，品牌蓝（#2e63e6，取自应用图标渐变）压深了一档，
   保证白底上的对比度够（浅色主题里最容易踩的坑就是照搬原色导致字发飘）。
   卡片在浅底上没有深色底那样的天然反差，所以一律给描边 + 极轻投影。
   ========================================================================== */

:root {
  --bg: #ffffff;
  --bg-soft: #f4f7fe;
  --card: #ffffff;
  --card-border: #e3e9f6;
  --text: #131c33;
  --text-dim: #4d5a7a;
  --text-faint: #77839f;
  --brand: #2e63e6;
  --brand-strong: #1f4fd0;
  --brand-soft: rgba(46, 99, 230, 0.08);
  --ok: #0f9d6e;
  --warn: #b26a00;
  --shadow-card: 0 1px 2px rgba(19, 28, 51, 0.04), 0 6px 18px rgba(19, 28, 51, 0.04);
  --radius: 16px;
  --maxw: 1080px;
}

* { 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", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

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

/* --------------------------------------------------------------------------
   顶部导航
   -------------------------------------------------------------------------- */

.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid #eaeef8;
}

.nav .wrap {
  display: flex;
  align-items: center;
  gap: 28px;
  height: 64px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: 0.5px;
  /* 导航是 flex 容器，CJK 文本的最小不可断行单位是一个字 ——
     空间一紧「泡泡加速」就会被压成一个字一行竖着排，必须钉死不换行不收缩。 */
  white-space: nowrap;
  flex-shrink: 0;
}
.brand:hover { text-decoration: none; }
.brand img { width: 30px; height: 30px; display: block; }
.brand small {
  color: var(--text-faint);
  font-weight: 500;
  font-size: 12px;
  margin-left: 2px;
}

.nav-links {
  display: flex;
  gap: 24px;
  margin-left: auto;
}
.nav-links a {
  color: var(--text-dim);
  font-size: 14.5px;
}
.nav-links a:hover { color: var(--text); text-decoration: none; }

/* --------------------------------------------------------------------------
   按钮
   -------------------------------------------------------------------------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 26px;
  border-radius: 12px;
  font-size: 15.5px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.12s ease, background 0.12s ease, border-color 0.12s ease;
  white-space: nowrap;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn-primary {
  background: linear-gradient(135deg, #3d7bff, #2e63e6);
  color: #fff;
  box-shadow: 0 6px 18px rgba(46, 99, 230, 0.28);
}
.btn-primary:hover { background: linear-gradient(135deg, #4d86ff, #3a6ef0); }

.btn-ghost {
  background: #fff;
  color: var(--text);
  border-color: #d5ddee;
}
/* 浅色主题下的必改项：hover 不能再走「变白字」，那在白底上等于把字擦掉。 */
.btn-ghost:hover { border-color: var(--brand); color: var(--brand); }

.btn-sm { padding: 9px 18px; font-size: 14px; border-radius: 10px; }

.btn[aria-disabled="true"] {
  opacity: 0.55;
  pointer-events: none;
}

/* --------------------------------------------------------------------------
   Hero
   -------------------------------------------------------------------------- */

.hero {
  position: relative;
  overflow: hidden;
  padding: 96px 0 84px;
  text-align: center;
  background:
    radial-gradient(600px 320px at 50% -60px, rgba(46, 99, 230, 0.14), transparent 70%),
    radial-gradient(900px 500px at 85% 110%, rgba(46, 99, 230, 0.07), transparent 70%),
    linear-gradient(180deg, #f8faff, #ffffff);
}

.hero::before {
  /* 细网格背景：加一点「技术产品」的质感，纯 CSS 实现 */
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(46, 99, 230, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(46, 99, 230, 0.07) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(640px 400px at 50% 0%, #000 30%, transparent 75%);
  pointer-events: none;
}

.hero .wrap { position: relative; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 999px;
  background: #fff;
  border: 1px solid rgba(46, 99, 230, 0.28);
  color: var(--brand-strong);
  font-size: 13.5px;
}

.hero h1 {
  margin: 22px 0 14px;
  font-size: 52px;
  line-height: 1.15;
  letter-spacing: 1px;
}
.hero h1 .accent {
  /* 浅底上渐变要往深的一端收，否则末尾那截亮蓝在白底上几乎看不见 */
  background: linear-gradient(120deg, #3d7bff, #1f4fd0 55%, #2e63e6);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero p.lead {
  margin: 0 auto;
  max-width: 640px;
  color: var(--text-dim);
  font-size: 18px;
}

.hero-cta {
  margin-top: 36px;
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

.hero-meta {
  margin-top: 30px;
  display: flex;
  gap: 26px;
  justify-content: center;
  flex-wrap: wrap;
  color: var(--text-faint);
  font-size: 13.5px;
}
.hero-meta span { display: inline-flex; align-items: center; gap: 7px; }
.hero-meta .dot { width: 6px; height: 6px; border-radius: 50%; background: var(--ok); }

/* --------------------------------------------------------------------------
   区块通用
   -------------------------------------------------------------------------- */

section { padding: 76px 0; }
section.alt { background: var(--bg-soft); }

.sec-head { text-align: center; margin-bottom: 44px; }
.sec-head h2 {
  margin: 0 0 10px;
  font-size: 32px;
  letter-spacing: 1px;
}
.sec-head p {
  margin: 0 auto;
  max-width: 560px;
  color: var(--text-dim);
  font-size: 15.5px;
}

/* --------------------------------------------------------------------------
   特性网格
   -------------------------------------------------------------------------- */

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.feature {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 24px 22px;
  box-shadow: var(--shadow-card);
}
.feature .icon {
  width: 42px;
  height: 42px;
  border-radius: 11px;
  background: var(--brand-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}
.feature .icon svg { width: 22px; height: 22px; stroke: #2e63e6; }
.feature h3 { margin: 0 0 6px; font-size: 17px; }
.feature p { margin: 0; color: var(--text-dim); font-size: 14.5px; }

/* --------------------------------------------------------------------------
   下载卡片
   -------------------------------------------------------------------------- */

.dl-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
  max-width: 820px;
  margin: 0 auto;
}

.dl-card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 28px 26px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
  position: relative;
  box-shadow: var(--shadow-card);
}
.dl-card.recommended {
  border-color: rgba(46, 99, 230, 0.45);
  box-shadow: 0 0 0 1px rgba(46, 99, 230, 0.18), 0 12px 30px rgba(46, 99, 230, 0.13);
}
.dl-card .tag {
  position: absolute;
  top: -11px;
  left: 22px;
  padding: 2px 12px;
  border-radius: 999px;
  background: var(--brand);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
}
/* 卡片是静态 HTML，「推荐」标签由 main.js 决定挂在哪张上：
   没被选中的一律 hidden。显式写一条，免得将来有人给 .tag 加 display 时把它顶出来。 */
.dl-card .tag[hidden] { display: none; }
.dl-head { display: flex; align-items: center; gap: 12px; margin-bottom: 8px; }
.dl-head img { width: 44px; height: 44px; }
.dl-head .name { font-size: 19px; font-weight: 700; }
.dl-head .os { color: var(--text-faint); font-size: 13px; }
.dl-req { color: var(--text-faint); font-size: 13.5px; margin: 0; }
.dl-file {
  font-family: ui-monospace, SFMono-Regular, Consolas, "Courier New", monospace;
  font-size: 12.5px;
  color: var(--text-dim);
  word-break: break-all;
}
.dl-extra { color: var(--text-faint); font-size: 12px; word-break: break-all; }
.dl-card .btn { margin-top: 16px; align-self: stretch; }

.dl-note {
  max-width: 820px;
  margin: 18px auto 0;
  color: var(--text-faint);
  font-size: 13px;
  text-align: center;
}

/* --------------------------------------------------------------------------
   价目表
   -------------------------------------------------------------------------- */

.price-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 14px;
}

.plan {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 22px 18px;
  text-align: center;
  position: relative;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-card);
}
.plan.best {
  border-color: rgba(46, 99, 230, 0.45);
  box-shadow: 0 0 0 1px rgba(46, 99, 230, 0.18), 0 12px 30px rgba(46, 99, 230, 0.12);
}
.plan .tag {
  position: absolute;
  top: -11px;
  left: 50%;
  transform: translateX(-50%);
  padding: 2px 12px;
  border-radius: 999px;
  background: var(--brand);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  white-space: nowrap;
}
.plan .name { font-size: 16px; font-weight: 700; }
.plan .price { margin: 10px 0 2px; font-size: 30px; font-weight: 800; letter-spacing: 0.5px; }
.plan .price small { font-size: 14px; font-weight: 500; color: var(--text-dim); }
.plan .unit { color: var(--text-faint); font-size: 12.5px; min-height: 20px; }
.plan .months { margin-top: auto; padding-top: 12px; color: var(--text-faint); font-size: 12.5px; }

.price-note {
  margin: 20px auto 0;
  max-width: 640px;
  text-align: center;
  color: var(--text-dim);
  font-size: 14px;
  background: var(--brand-soft);
  border: 1px solid rgba(46, 99, 230, 0.22);
  border-radius: 12px;
  padding: 12px 18px;
}

/* --------------------------------------------------------------------------
   FAQ
   -------------------------------------------------------------------------- */

.faq { max-width: 760px; margin: 0 auto; }
.faq details {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 0 20px;
  margin-bottom: 12px;
  box-shadow: var(--shadow-card);
}
.faq details[open] { border-color: rgba(46, 99, 230, 0.35); }
.faq summary {
  cursor: pointer;
  padding: 16px 0;
  font-weight: 600;
  font-size: 15.5px;
  list-style: none;
  position: relative;
  padding-right: 34px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--brand);
  font-size: 20px;
  font-weight: 400;
}
.faq details[open] summary::after { content: "−"; }
.faq .answer { padding: 0 0 16px; color: var(--text-dim); font-size: 14.5px; }
.faq .answer p { margin: 0 0 8px; }
.faq .answer p:last-child { margin-bottom: 0; }

/* --------------------------------------------------------------------------
   页脚
   -------------------------------------------------------------------------- */

footer {
  border-top: 1px solid #eaeef8;
  padding: 34px 0 44px;
  color: var(--text-faint);
  font-size: 13.5px;
}
footer .wrap {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
footer .brand { font-size: 15px; }
footer .brand img { width: 24px; height: 24px; }
footer .legal { margin-left: auto; }

/* --------------------------------------------------------------------------
   响应式
   -------------------------------------------------------------------------- */

@media (max-width: 900px) {
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .price-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 640px) {
  .nav-links { display: none; }
  /* 窄屏收掉品牌旁的英文副标，给右边「下载客户端」按钮让位，
     也保证主标题绝不换行竖排 */
  .brand small { display: none; }
  .hero { padding: 64px 0 60px; }
  .hero h1 { font-size: 36px; }
  .hero p.lead { font-size: 16px; }
  section { padding: 56px 0; }
  .grid-3 { grid-template-columns: 1fr; }
  .dl-grid { grid-template-columns: 1fr; }
  .price-grid { grid-template-columns: 1fr 1fr; }
  footer .legal { margin-left: 0; }
}