/* ===== 火狐浏览器 Firefox 官网风格 ===== */
:root {
  --ff-orange: #ff7139;
  --ff-orange-dark: #e25c25;
  --ff-blue: #0060df;
  --ff-blue-dark: #003eaa;
  --ff-bg: #f9f9fb;
  --ff-text: #20123a;
  --ff-muted: #5b5b66;
  --ff-card: #ffffff;
  --ff-radius: 12px;
  --ff-shadow: 0 8px 24px rgba(32, 18, 58, 0.08);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: var(--ff-text);
  background: var(--ff-bg);
  line-height: 1.6;
}

a {
  text-decoration: none;
  color: inherit;
}

img {
  max-width: 100%;
  display: block;
}

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== 导航栏 ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid #eee;
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 700;
}

.logo-icon {
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-links a {
  font-size: 15px;
  color: var(--ff-text);
  transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--ff-orange);
}

.nav-download {
  background: var(--ff-orange);
  color: #fff !important;
  padding: 8px 20px;
  border-radius: 999px;
  font-weight: 600;
  transition: background 0.2s;
}

.nav-download:hover {
  background: var(--ff-orange-dark);
}

/* ===== Hero 区 ===== */
.hero {
  background: linear-gradient(135deg, #ff7139 0%, #ff9e5e 45%, #0060df 130%);
  color: #fff;
  padding: 88px 0 72px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::after {
  content: "";
  position: absolute;
  right: -120px;
  bottom: -160px;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.08);
}

.hero-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.18);
  border: 1px solid rgba(255, 255, 255, 0.3);
  padding: 6px 16px;
  border-radius: 999px;
  font-size: 13px;
  margin-bottom: 24px;
}

.hero h1 {
  font-size: 52px;
  font-weight: 800;
  letter-spacing: -1px;
  line-height: 1.15;
}

.hero p {
  font-size: 18px;
  max-width: 640px;
  margin: 20px auto 36px;
  opacity: 0.95;
}

.btn-group {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  position: relative;
  z-index: 1;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: #fff;
  color: var(--ff-orange);
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.18);
}

.btn-primary:hover {
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.22);
}

.btn-ghost {
  background: transparent;
  color: #fff;
  border: 2px solid rgba(255, 255, 255, 0.6);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.12);
}

/* ===== 特性卡片 ===== */
.features {
  padding: 72px 0;
}

.section-title {
  text-align: center;
  font-size: 34px;
  font-weight: 700;
  margin-bottom: 12px;
}

.section-sub {
  text-align: center;
  color: var(--ff-muted);
  font-size: 16px;
  max-width: 560px;
  margin: 0 auto 44px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
}

.card {
  background: var(--ff-card);
  border-radius: var(--ff-radius);
  padding: 32px 24px;
  box-shadow: var(--ff-shadow);
  transition: transform 0.25s, box-shadow 0.25s;
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 36px rgba(32, 18, 58, 0.14);
}

.card-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  font-size: 26px;
}

.icon-orange { background: rgba(255, 113, 57, 0.12); }
.icon-blue { background: rgba(0, 96, 223, 0.12); }
.icon-purple { background: rgba(132, 94, 234, 0.12); }
.icon-green { background: rgba(53, 181, 127, 0.12); }

.card h3 {
  font-size: 19px;
  margin-bottom: 10px;
}

.card p {
  color: var(--ff-muted);
  font-size: 14.5px;
}

/* ===== 品牌区 ===== */
.brand {
  background: var(--ff-text);
  color: #fff;
  padding: 72px 0;
}

.brand-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.brand h2 {
  font-size: 32px;
  margin-bottom: 16px;
}

.brand p {
  color: rgba(255, 255, 255, 0.82);
  margin-bottom: 12px;
}

.brand-stats {
  display: flex;
  gap: 36px;
  margin-top: 24px;
}

.stat b {
  display: block;
  font-size: 30px;
  color: var(--ff-orange);
}

.stat span {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.7);
}

/* ===== 页脚 ===== */
.footer {
  background: #17142a;
  color: rgba(255, 255, 255, 0.72);
  padding: 40px 0 32px;
  font-size: 14px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.72);
  transition: color 0.2s;
}

.footer-links a:hover {
  color: var(--ff-orange);
}

/* ===== 下载页 ===== */
.download-hero {
  background: linear-gradient(135deg, #0060df 0%, #003eaa 100%);
  color: #fff;
  padding: 72px 0;
  text-align: center;
}

.download-hero h1 {
  font-size: 40px;
  margin-bottom: 12px;
}

.download-hero p {
  opacity: 0.92;
  max-width: 600px;
  margin: 0 auto;
}

.platforms {
  padding: 64px 0;
}

.platform-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 20px;
  margin-bottom: 48px;
}

.platform-card {
  background: var(--ff-card);
  border-radius: var(--ff-radius);
  padding: 28px 20px;
  text-align: center;
  box-shadow: var(--ff-shadow);
  transition: transform 0.2s, box-shadow 0.2s;
}

.platform-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 14px 30px rgba(0, 96, 223, 0.18);
}

.platform-icon {
  font-size: 40px;
  margin-bottom: 12px;
}

.platform-card h3 {
  font-size: 17px;
  margin-bottom: 14px;
}

.dl-btn {
  display: block;
  background: var(--ff-blue);
  color: #fff;
  padding: 10px 0;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  transition: background 0.2s;
}

.dl-btn:hover {
  background: var(--ff-blue-dark);
}

.info-box {
  background: #eef3fe;
  border: 1px solid #d4e0fa;
  border-radius: var(--ff-radius);
  padding: 28px;
  margin-bottom: 24px;
}

.info-box h3 {
  color: var(--ff-blue);
  margin-bottom: 12px;
}

.info-box ul {
  padding-left: 20px;
  color: var(--ff-text);
}

.info-box li {
  margin-bottom: 8px;
}

/* ===== 404 页 ===== */
.error-section {
  min-height: calc(100vh - 176px);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 80px 24px;
}

.error-code {
  font-size: 140px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--ff-orange), var(--ff-blue));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1;
}

.error-section h1 {
  font-size: 32px;
  margin: 16px 0 12px;
}

.error-section p {
  color: var(--ff-muted);
  max-width: 460px;
  margin: 0 auto 32px;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .hero h1 { font-size: 36px; }
  .download-hero h1 { font-size: 30px; }
  .error-code { font-size: 96px; }
  .brand-inner { grid-template-columns: 1fr; }
  .nav-links a:not(.nav-download) { display: none; }
  .footer-inner { flex-direction: column; text-align: center; }
}