/* ============================================
   LiveTV 播放器官网 - 科技感主题样式
   ============================================ */

/* ---------- CSS 变量 ---------- */
:root {
  --bg-primary: #0a0a14;
  --bg-secondary: #10101e;
  --bg-card: rgba(16, 16, 40, 0.75);
  --bg-card-hover: rgba(20, 20, 55, 0.9);
  --color-accent: #00d4ff;
  --color-accent2: #7c3aed;
  --color-accent3: #06b6d4;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-accent: rgba(0, 212, 255, 0.3);
  --glow-cyan: 0 0 20px rgba(0, 212, 255, 0.4);
  --glow-purple: 0 0 20px rgba(124, 58, 237, 0.4);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- 全局重置 ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; }
ul, ol { list-style: none; }
img { max-width: 100%; display: block; }
button { cursor: pointer; border: none; outline: none; font-family: inherit; }
input, textarea, select { font-family: inherit; outline: none; }

/* ---------- 粒子背景容器 ---------- */
#particles-bg {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* ---------- 网格背景 ---------- */
.grid-bg {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background-image:
    linear-gradient(rgba(0, 212, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 255, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  z-index: 0;
  pointer-events: none;
}

/* ---------- 顶部导航 ---------- */
.top-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  padding: 0 24px;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10, 10, 20, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition-normal);
}

.top-nav.scrolled {
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.4);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.5px;
}

.nav-logo .logo-icon {
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  color: #fff;
  box-shadow: var(--glow-cyan);
}

.nav-links {
  display: flex;
  gap: 4px;
  align-items: center;
}

.nav-link {
  padding: 8px 18px;
  border-radius: 24px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--transition-fast);
  position: relative;
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.05);
}

.nav-link.active {
  color: var(--color-accent);
  background: rgba(0, 212, 255, 0.1);
  box-shadow: 0 0 12px rgba(0, 212, 255, 0.15);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--color-accent);
  border-radius: 2px;
}

/* 移动端菜单按钮 */
.menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  background: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border-radius: var(--radius-sm);
  transition: var(--transition-fast);
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition-fast);
}

/* ---------- 主内容区 ---------- */
.main-content {
  position: relative;
  z-index: 1;
  padding-top: 68px;
}

/* ---------- 页面区块 ---------- */
.page-section {
  min-height: 100vh;
  display: none;
  padding: 40px 24px;
}

.page-section.active {
  display: block;
}

/* ---------- Hero 首页横幅 ---------- */
.hero-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 68px);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  width: 500px;
  height: 500px;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.15;
  pointer-events: none;
}

.hero-glow.cyan {
  top: -100px;
  left: -50px;
  background: var(--color-accent);
}

.hero-glow.purple {
  bottom: -100px;
  right: -50px;
  background: var(--color-accent2);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(0, 212, 255, 0.1);
  border: 1px solid var(--border-accent);
  border-radius: 50px;
  font-size: 0.85rem;
  color: var(--color-accent);
  margin-bottom: 28px;
  animation: fadeInUp 0.8s ease;
}

.hero-badge .dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent);
  animation: pulse-dot 2s infinite;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 16px;
  letter-spacing: -1px;
  animation: fadeInUp 0.8s ease 0.1s both;
}

.hero-title .gradient-text {
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  margin-bottom: 40px;
  max-width: 560px;
  animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: center;
  animation: fadeInUp 0.8s ease 0.3s both;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: 50px;
  font-size: 0.95rem;
  font-weight: 600;
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
  color: #fff;
  box-shadow: 0 4px 25px rgba(0, 212, 255, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 35px rgba(0, 212, 255, 0.45);
}

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  box-shadow: 0 0 20px rgba(0, 212, 255, 0.15);
  transform: translateY(-2px);
}

.btn-glass {
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.btn-glass:hover {
  background: rgba(255, 255, 255, 0.1);
  transform: translateY(-2px);
}

/* ---------- 容器 ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 12px;
}

.section-header {
  text-align: center;
  margin-bottom: 50px;
}

.section-header h2 {
  font-size: 2.2rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.section-header h2 .gradient-text {
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 500px;
  margin: 0 auto;
}

/* ---------- 特性卡片网格 ---------- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  margin-top: 60px;
}

/* ---------- 卡片 ---------- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-accent), transparent);
  opacity: 0;
  transition: var(--transition-normal);
}

.card:hover {
  transform: translateY(-6px);
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
  box-shadow: 0 8px 40px rgba(0, 212, 255, 0.12);
}

.card:hover::before {
  opacity: 1;
}

.card-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.card-icon.cyan {
  background: rgba(0, 212, 255, 0.12);
  color: var(--color-accent);
}

.card-icon.purple {
  background: rgba(124, 58, 237, 0.12);
  color: var(--color-accent2);
}

.card-icon.green {
  background: rgba(16, 185, 129, 0.12);
  color: var(--color-success);
}

.card-icon.amber {
  background: rgba(245, 158, 11, 0.12);
  color: var(--color-warning);
}

.card h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ---------- 平台卡片（下载页） ---------- */
.platform-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 30px;
}

.platform-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 40px 32px;
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
}

.platform-card:hover {
  border-color: var(--border-accent);
  box-shadow: 0 12px 50px rgba(0, 212, 255, 0.15);
  transform: translateY(-4px);
}

.platform-card::after {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at center, rgba(0, 212, 255, 0.03) 0%, transparent 50%);
  pointer-events: none;
}

.platform-card.windows .platform-badge {
  background: linear-gradient(135deg, #00a4ef, #0078d4);
}

.platform-card.android .platform-badge {
  background: linear-gradient(135deg, #3ddc84, #00b862);
}

.platform-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 50px;
  font-size: 0.8rem;
  font-weight: 600;
  color: #fff;
  margin-bottom: 20px;
}

.platform-name {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.platform-version {
  font-size: 0.9rem;
  color: var(--color-accent);
  margin-bottom: 10px;
  font-family: 'Consolas', 'Courier New', monospace;
}

.platform-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.platform-features {
  margin-bottom: 24px;
}

.platform-features li {
  position: relative;
  padding-left: 24px;
  padding-bottom: 8px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.platform-features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 8px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.5);
}


/* ---------- 下载按钮组 ---------- */
.download-links {
  display: flex;
  flex-direction: row;
  gap: 10px;
}

.btn-download {
  display: flex;
  flex: 1;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 12px;
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 600;
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid var(--border-accent);
  color: var(--color-accent);
  transition: var(--transition-normal);
  white-space: nowrap;
}

.btn-download:hover {
  background: rgba(0, 212, 255, 0.18);
  border-color: var(--color-accent);
  box-shadow: 0 0 18px rgba(0, 212, 255, 0.25);
  transform: translateY(-2px);
}

.btn-download:nth-child(2) {
  background: rgba(124, 58, 237, 0.08);
  border-color: rgba(124, 58, 237, 0.3);
  color: var(--color-accent2);
}

.btn-download:nth-child(2):hover {
  background: rgba(124, 58, 237, 0.18);
  border-color: var(--color-accent2);
  box-shadow: 0 0 18px rgba(124, 58, 237, 0.25);
}

.btn-download:nth-child(3) {
  background: rgba(16, 185, 129, 0.08);
  border-color: rgba(16, 185, 129, 0.3);
  color: var(--color-success);
}

.btn-download:nth-child(3):hover {
  background: rgba(16, 185, 129, 0.18);
  border-color: var(--color-success);
  box-shadow: 0 0 18px rgba(16, 185, 129, 0.25);
}

/* ---------- 升级时间线 ---------- */
.timeline {
  position: relative;
  max-width: 700px;
  margin: 0 auto;
  padding-left: 40px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 15px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--color-accent), var(--color-accent2), transparent);
}

.timeline-item {
  position: relative;
  padding-bottom: 40px;
}

.timeline-dot {
  position: absolute;
  left: -32px;
  top: 4px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 12px rgba(0, 212, 255, 0.4);
  border: 3px solid var(--bg-primary);
  z-index: 1;
}

.timeline-item.current .timeline-dot {
  background: var(--color-accent2);
  box-shadow: 0 0 16px rgba(124, 58, 237, 0.5);
  animation: pulse-dot 2s infinite;
}

.timeline-content {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  transition: var(--transition-normal);
}

.timeline-content:hover {
  border-color: var(--border-accent);
  box-shadow: 0 4px 20px rgba(0, 212, 255, 0.1);
  transform: translateX(4px);
}

.timeline-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
  flex-wrap: wrap;
}

.timeline-version {
  font-size: 1.1rem;
  font-weight: 700;
  font-family: 'Consolas', monospace;
  color: var(--color-accent);
}

.timeline-badge {
  padding: 3px 10px;
  border-radius: 50px;
  font-size: 0.7rem;
  font-weight: 600;
  color: #fff;
}

.timeline-badge.stable {
  background: var(--color-success);
}

.timeline-badge.beta {
  background: var(--color-warning);
}

.timeline-date {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-left: auto;
}

.timeline-content ul {
  list-style: none;
}

.timeline-content li {
  position: relative;
  padding-left: 18px;
  padding-bottom: 6px;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.timeline-content li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-size: 0.75rem;
}

.timeline-downloads {
  display: flex;
  gap: 12px;
  margin-top: 16px;
  flex-wrap: wrap;
}

/* ---------- 反馈页（左右布局） ---------- */
.feedback-layout {
  display: grid;
  grid-template-columns: 1fr 420px;
  gap: 24px;
  max-width: 1200px;
  margin: 0 auto;
  align-items: start;
}

.feedback-list-panel,
.feedback-form-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 28px;
  backdrop-filter: blur(10px);
}

.feedback-list-title,
.feedback-form-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 18px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-primary);
}

.feedback-list-panel {
  max-height: calc(100vh - 200px);
  overflow-y: auto;
  position: sticky;
  top: 90px;
}

.feedback-list-panel::-webkit-scrollbar {
  width: 5px;
}

.feedback-list-panel::-webkit-scrollbar-track {
  background: transparent;
}

.feedback-list-panel::-webkit-scrollbar-thumb {
  background: var(--border-accent);
  border-radius: 10px;
}

.form-group {
  margin-bottom: 22px;
}

.form-label {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.form-label .required {
  color: var(--color-danger);
  margin-left: 2px;
}

.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 12px 16px;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.9rem;
  transition: var(--transition-fast);
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(0, 212, 255, 0.1);
}

.form-select {
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M6 8L1 3h10z' fill='%2394a3b8'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 16px center;
  padding-right: 40px;
}

.form-select option {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.form-textarea {
  min-height: 160px;
  resize: vertical;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.form-hint {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 6px;
}

/* ---------- 反馈列表 ---------- */
.feedback-items {
  display: grid;
  gap: 14px;
}

.feedback-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 20px 24px;
  transition: var(--transition-fast);
}

.feedback-item:hover {
  border-color: var(--border-accent);
}

.feedback-item-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 10px;
  flex-wrap: wrap;
  gap: 8px;
}

.feedback-item-category {
  padding: 3px 10px;
  border-radius: 50px;
  font-size: 0.72rem;
  font-weight: 600;
  color: #fff;
}

.feedback-item-category.bug {
  background: var(--color-danger);
}

.feedback-item-category.suggestion {
  background: var(--color-accent);
}

.feedback-item-category.channel {
  background: var(--color-warning);
}

.feedback-item-category.compat {
  background: var(--color-accent2);
}

.feedback-item-category.other {
  background: var(--text-muted);
}

.feedback-item-date {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.feedback-item-contact {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.feedback-item-content {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.feedback-empty {
  text-align: center;
  padding: 40px;
  color: var(--text-muted);
}

.feedback-empty-icon {
  font-size: 3rem;
  margin-bottom: 12px;
}

/* ---------- 统计数字 ---------- */
.stats-row {
  display: flex;
  justify-content: center;
  gap: 60px;
  margin-top: 50px;
  flex-wrap: wrap;
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ---------- Toast 提示 ---------- */
.toast {
  position: fixed;
  top: 24px;
  right: 24px;
  z-index: 9999;
  padding: 14px 24px;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 500;
  color: #fff;
  transform: translateX(120%);
  transition: transform 0.4s cubic-bezier(0.22, 0.61, 0.36, 1);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}

.toast.show {
  transform: translateX(0);
}

.toast.success {
  background: linear-gradient(135deg, #10b981, #059669);
}

.toast.error {
  background: linear-gradient(135deg, #ef4444, #dc2626);
}

.toast.info {
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent2));
}

/* ---------- 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 48px 24px 24px;
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
}

.footer-col h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.footer-col p {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.footer-col .nav-link {
  display: block;
  padding: 4px 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-col .nav-link:hover,
.footer-col .nav-link.active {
  color: var(--color-accent);
  background: none;
  box-shadow: none;
}

.footer-col .nav-link.active::after {
  display: none;
}

.footer-bottom {
  max-width: 1200px;
  margin: 30px auto 0;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---------- 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 999;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: rgba(0, 212, 255, 0.1);
  border: 1px solid var(--border-accent);
  color: var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  backdrop-filter: blur(10px);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: rgba(0, 212, 255, 0.2);
  box-shadow: 0 0 20px rgba(0, 212, 255, 0.3);
  transform: translateY(-3px);
}

/* ---------- 动画 ---------- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse-dot {
  0%, 100% { box-shadow: 0 0 8px rgba(0, 212, 255, 0.4); }
  50% { box-shadow: 0 0 20px rgba(0, 212, 255, 0.7), 0 0 40px rgba(0, 212, 255, 0.3); }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

@keyframes glow-pulse {
  0%, 100% { opacity: 0.15; }
  50% { opacity: 0.25; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
  .menu-toggle {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: 68px;
    left: 0;
    right: 0;
    background: rgba(10, 10, 20, 0.95);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 16px;
    gap: 4px;
    border-bottom: 1px solid var(--border-color);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: var(--transition-normal);
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav-link {
    padding: 12px 16px;
    border-radius: var(--radius-md);
    width: 100%;
  }

  .platform-cards {
    grid-template-columns: 1fr;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .stats-row {
    gap: 30px;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .hero-title {
    font-size: 2rem;
  }

  .page-section {
    padding: 30px 16px;
  }

  .feedback-layout {
    grid-template-columns: 1fr;
  }

  .feedback-list-panel,
  .feedback-form-panel {
    padding: 20px 16px;
  }

  .feedback-list-panel {
    max-height: none;
    position: static;
  }
}

@media (max-width: 480px) {
  .hero-buttons {
    flex-direction: column;
    width: 100%;
  }

  .hero-buttons .btn {
    width: 100%;
    justify-content: center;
  }

  .timeline {
    padding-left: 30px;
  }

  .timeline-dot {
    left: -23px;
    width: 12px;
    height: 12px;
  }

  .timeline-downloads {
    flex-direction: column;
  }
}