/* File-Rocket 4.0 Design System */
:root {
  --primary-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
  --primary-color: #6366f1;
  --secondary-color: #a855f7;
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(255, 255, 255, 0.5);
  --glass-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.15);
  --text-main: #1f2937;
  --text-sub: #4b5563;
  --text-light: rgba(255, 255, 255, 0.9);
  --radius-lg: 24px;
  --radius-md: 16px;
  --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

/* 移动端触摸优化 */
.btn-primary,
.card-button,
.back-link,
.code-box {
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  touch-action: manipulation;
}

/* 优化触摸反馈 */
.btn-primary:active,
.card-button:active,
.back-link:active,
.code-box:active {
  transform: scale(0.98);
  transition: transform 0.1s ease;
}

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    sans-serif;
  min-height: 100vh;
  color: var(--text-main);
  /* 动态流动背景 */
  /* background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
  background-size: 400% 400%;
  animation: gradientBG 15s ease infinite; */
  background-image: url("../image/background1.jpeg");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed; /* 可选，背景固定不随滚动 */
  display: flex;
  flex-direction: column;
}

@keyframes gradientBG {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 20px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  position: relative;
  z-index: 1;
}

/* Header */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 60px;
  animation: slideDown 0.8s ease-out;
  flex-wrap: wrap; /* 允许换行防止重叠 */
  gap: 20px; /* 元素间最小间距 */
}

.logo {
  font-size: 2.2rem;
  font-weight: 800;
  color: #000;
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  letter-spacing: -1px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0; /* 防止Logo被压缩 */
}

.subtitle {
  color: var(--text-light);
  font-weight: 500;
  font-size: 1.1rem;
  margin-top: 4px;
}

/* 返回按钮 - 玻璃拟态 */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 50px;
  color: #000;
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.back-link:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

/* 移动端底部返回按钮 */
.mobile-back-btn {
  display: none; /* 默认隐藏，仅移动端显示 */
  margin-top: 40px;
  margin-bottom: 20px;
  padding: 14px 32px;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 2px solid rgba(99, 102, 241, 0.3);
  border-radius: 20px;
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 600;
  font-size: 1rem;
  transition: var(--transition);
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.15);
  align-items: center;
  gap: 8px;
  justify-content: center;
  width: fit-content;
  margin-left: auto;
  margin-right: auto;
}

.mobile-back-btn:hover {
  background: white;
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(99, 102, 241, 0.25);
  border-color: var(--primary-color);
}

/* 主内容区 */
.main-content,
.upload-content,
.receive-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
}

/* 卡片容器 - 统一布局 */
.action-cards {
  display: grid;
  /* grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); */
  grid-template-columns: minmax(320px, 1fr);
  gap: 40px;
  width: 100%;
  max-width: 900px;
  perspective: 1000px;
}

/* 通用卡片样式 - 玻璃拟态 */
.card,
.upload-card,
.receive-card {
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: var(--radius-lg);
  padding: 50px 40px;
  text-align: center;
  box-shadow: var(--glass-shadow);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
  overflow: hidden;
}

/* 仅首页卡片的交互效果 */
.card {
  cursor: pointer;
  min-height: 420px;
  justify-content: center;
}
/* 已删除紫色上边框效果 */

.card:hover {
  transform: translateY(-10px) scale(1.02);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
  background: rgba(255, 255, 255, 0.85);
}
/* 已删除悬停时的上边框显示 */

/* 详情页卡片特定样式 */
.upload-card,
.receive-card {
  max-width: 600px;
  width: 100%;
  min-height: 500px;
  justify-content: flex-start;
  animation: fadeInUp 0.6s ease-out;
}

.upload-card h2,
.receive-card h2 {
  font-size: 2rem;
  margin-bottom: 40px;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  font-weight: 800;
}

/* 图标和文字 */
.card-icon {
  font-size: 4.5rem;
  margin-bottom: 25px;
  filter: drop-shadow(0 10px 10px rgba(0, 0, 0, 0.1));
  transition: var(--transition);
}

.card:hover .card-icon {
  transform: scale(1.1) rotate(5deg);
}

.card h3 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-main);
}

.card p {
  color: var(--text-sub);
  margin-bottom: 35px;
  font-size: 1.1rem;
  line-height: 1.5;
}

/* 统一按钮样式 - 重构核心 */
.btn-primary,
.card-button,
.select-file-btn,
.connect-btn,
.generate-code-btn,
.new-transfer-btn,
.retry-btn,
.send-btn,
.receive-btn {
  background: var(--primary-gradient) !important;
  color: white !important;
  border: none !important;
  border-radius: 50px !important;
  padding: 0 !important; /* Reset padding for flex centering */
  width: 180px !important;
  height: 56px !important;
  font-size: 1.15rem !important;
  font-weight: 600 !important;
  cursor: pointer !important;
  transition: var(--transition) !important;
  display: inline-flex !important;
  align-items: center !important;
  justify-content: center !important;
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3) !important;
  text-decoration: none !important;
  position: relative !important;
  overflow: hidden !important;
  letter-spacing: 0.5px !important;
  white-space: nowrap !important;
  outline: none !important;
  line-height: 1 !important;
}

/* 按钮悬停光效 */
.btn-primary::after,
.card-button::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(rgba(255, 255, 255, 0.2), rgba(255, 255, 255, 0));
  opacity: 0;
  transition: var(--transition);
}

.btn-primary:hover,
.card-button:hover,
.select-file-btn:hover,
.connect-btn:hover,
.send-btn:hover,
.receive-btn:hover {
  transform: translateY(-2px) scale(1.02) !important;
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.4) !important;
}

.btn-primary:hover::after {
  opacity: 1;
}

.btn-primary:active,
.card-button:active {
  transform: translateY(1px);
}

.decline-btn {
  background: #f3f4f6;
  color: var(--text-main);
  border: none;
  border-radius: 50px;
  width: 140px;
  height: 56px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.decline-btn:hover {
  background: #e5e7eb;
  transform: translateY(-2px);
}

.accept-btn {
  background: var(--primary-gradient);
  color: white;
  border: none;
  border-radius: 50px;
  width: 140px;
  height: 56px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.accept-btn:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.4);
}

/* 交互区域优化 */
.file-drop-zone {
  border: 2px dashed #cbd5e1;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.5);
  padding: 60px 30px;
  width: 100%;
  min-height: 240px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  margin-bottom: 30px;
}

.file-drop-zone:hover,
.file-drop-zone.drag-over {
  border-color: var(--primary-color);
  background: rgba(99, 102, 241, 0.05);
  transform: scale(1.01);
}

.code-input-section {
  width: 100%;
  padding: 40px;
  background: rgba(255, 255, 255, 0.5);
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.8);
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* 分体式输入框设计 */
.code-input-wrapper {
  position: relative;
  display: flex;
  gap: 20px;
  justify-content: center;
  margin-bottom: 40px;
  cursor: text;
}

.code-box {
  width: 64px;
  height: 72px;
  background: white;
  border: 2px solid #e5e7eb;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--primary-color);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

/* 激活状态（聚焦或有值） */
.code-box.active {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.15);
  transform: translateY(-2px);
}

.code-box.filled {
  background: #f5f3ff;
  border-color: #8b5cf6;
}

/* 输入时的弹跳动画 */
@keyframes popBox {
  0% {
    transform: scale(0.95);
  }
  50% {
    transform: scale(1.1);
  }
  100% {
    transform: scale(1);
  }
}

.code-box.pop {
  animation: popBox 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.input-hint {
  margin-top: 20px;
  color: var(--text-sub);
}

/* 取件码展示 */
.pickup-code-display {
  background: #f8fafc;
  border-radius: var(--radius-md);
  padding: 30px;
  margin-bottom: 30px;
  border: 2px dashed var(--primary-color);
  width: 100%;
}

.pickup-code {
  font-size: 3.5rem;
  font-weight: 800;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: 8px;
  font-family: "Monaco", "Courier New", monospace;
  margin: 15px 0;
}

/* 文件详情 */
.file-details {
  background: rgba(255, 255, 255, 0.6);
  padding: 25px;
  border-radius: var(--radius-md);
  margin-bottom: 30px;
  width: 100%;
  display: flex;
  align-items: center;
  gap: 20px;
}

.file-icon {
  font-size: 3rem;
}

.file-info {
  text-align: left;
}

.file-name {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 5px;
  display: block;
}

.file-size {
  color: var(--text-sub);
  font-size: 0.9rem;
}

/* 特性列表 */
.features {
  display: flex;
  gap: 30px;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 60px;
}

.feature {
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  padding: 12px 24px;
  border-radius: 50px;
  color: white;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.95rem;
  border: 1px solid rgba(255, 255, 255, 0.2);
  transition: var(--transition);
}

.feature:hover {
  background: rgba(255, 255, 255, 0.25);
  transform: translateY(-2px);
}

/* 进度条 */
.progress-container {
  width: 100%;
  background: #e2e8f0;
  height: 12px;
  border-radius: 10px;
  overflow: hidden;
  margin: 20px 0;
}

.progress-fill {
  height: 100%;
  background: var(--primary-gradient);
  width: 0%;
  transition: width 0.3s ease;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(99, 102, 241, 0.5);
}

.progress-text {
  display: flex;
  justify-content: space-between;
  color: var(--text-sub);
  font-size: 0.9rem;
  font-weight: 500;
}

/* 状态指示器 */
.status-indicator {
  width: 80px;
  height: 80px;
  margin: 0 auto 25px;
  background: var(--primary-gradient);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
}

.pulse {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  animation: pulse 2s infinite;
  border: 4px solid white;
}

/* 成功/错误图标 */
.success-icon,
.error-icon {
  font-size: 5rem;
  margin-bottom: 20px;
  display: inline-block;
  animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

/* Footer */
.footer {
  text-align: center;
  color: rgba(255, 255, 255, 0.8);
  margin-top: auto;
  padding-top: 40px;
  font-size: 0.9rem;
}

/* 动画定义 */
@keyframes slideDown {
  from {
    transform: translateY(-20px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

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

@keyframes popIn {
  from {
    transform: scale(0);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

@keyframes pulse {
  0% {
    transform: scale(0.95);
    opacity: 1;
  }
  50% {
    transform: scale(1.05);
    opacity: 0.8;
  }
  100% {
    transform: scale(0.95);
    opacity: 1;
  }
}

@keyframes shake {
  0%,
  100% {
    transform: translateX(0);
  }
  10%,
  30%,
  50%,
  70%,
  90% {
    transform: translateX(-5px);
  }
  20%,
  40%,
  60%,
  80% {
    transform: translateX(5px);
  }
}

.shake {
  animation: shake 0.5s cubic-bezier(0.36, 0.07, 0.19, 0.97) both;
  color: #dc3545; /* 强调错误颜色 */
}

.stage {
  display: none;
  width: 100%;
  animation: fadeInUp 0.5s ease-out;
}

.stage.active {
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* 传输模式选择器 */
.transfer-mode-selector {
  background: rgba(255, 255, 255, 0.5);
  padding: 25px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.8);
}

.mode-option {
  margin-bottom: 12px;
  position: relative;
}

.mode-option input[type="radio"] {
  position: absolute;
  opacity: 0;
}

.mode-option label {
  display: flex;
  align-items: center;
  gap: 15px;
  padding: 18px;
  background: white;
  border: 2px solid #e5e7eb;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.mode-option input[type="radio"]:checked + label {
  border-color: var(--primary-color);
  background: #f5f3ff;
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.mode-option label:hover {
  border-color: var(--primary-color);
  transform: translateY(-2px);
}

.mode-icon {
  font-size: 2rem;
  flex-shrink: 0;
}

.mode-info {
  flex: 1;
  text-align: left;
}

.mode-info strong {
  display: block;
  color: var(--text-main);
  margin-bottom: 4px;
  font-size: 1rem;
}

.mode-info span {
  color: var(--text-sub);
  font-size: 0.85rem;
}

/* P2P NAT 检测显示 */
.nat-detection {
  background: rgba(255, 255, 255, 0.6);
  padding: 20px;
  border-radius: var(--radius-md);
  margin-top: 20px;
  margin-bottom: 30px;
  border: 2px dashed var(--primary-color);
}

.nat-info {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 15px;
}

.nat-type {
  display: inline-block;
  padding: 6px 16px;
  background: var(--primary-gradient);
  color: white;
  border-radius: 20px;
  font-weight: 600;
  font-size: 0.9rem;
}

.nat-success-rate {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

/* 响应式适配 */
/* === 平板端适配 (768px - 1024px) === */
@media (min-width: 769px) and (max-width: 1024px) {
  .container {
    padding: 40px 30px;
    max-width: 800px;
  }

  .card,
  .upload-card,
  .receive-card {
    padding: 40px 35px;
    max-width: 600px;
  }

  .pickup-code {
    font-size: 3rem;
    letter-spacing: 8px;
  }

  .code-input-wrapper {
    gap: 15px;
  }

  .code-box {
    width: 60px;
    height: 70px;
    font-size: 1.8rem;
  }

  .btn-primary,
  .card-button {
    width: 180px !important;
    height: 56px !important;
    padding: 0 !important;
    font-size: 1.1rem !important;
  }

  .header h1 {
    font-size: 3rem;
  }

  .header p {
    font-size: 1.3rem;
  }
}

/* === 移动端适配 (小于768px) === */
@media (max-width: 768px) {
  .container {
    padding: 15px;
    margin: 0;
  }

  .header {
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-bottom: 20px;
    padding: 60px 10px 10px;
  }

  .logo {
    justify-content: center;
    width: 100%;
    margin-bottom: 5px;
    font-size: 2.8rem;
  }

  .subtitle {
    font-size: 1.1rem;
    text-align: center;
    width: 100%;
    margin-bottom: 20px;
    opacity: 0.9;
  }

  /* 移动端隐藏顶部返回按钮，显示底部按钮 */
  .header .back-link {
    display: none !important;
  }

  .mobile-back-btn {
    display: flex;
    margin-top: 30px;
    margin-bottom: 20px;
  }

  /* 首页双卡片横向排列优化 */
  .action-cards {
    display: grid;
    /* grid-template-columns: 1fr 1fr; */
    grid-template-columns: 1fr;
    gap: 15px;
    width: 100%;
    margin-top: 0px;
  }

  .action-cards .card {
    margin: 0;
    min-height: 220px;
    padding: 25px 15px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    border-radius: 24px;
  }

  .action-cards .card-icon {
    font-size: 3rem;
    margin-bottom: 12px;
    margin-top: 5px;
  }

  .action-cards .card h3 {
    font-size: 1.3rem;
    margin-bottom: 8px;
    font-weight: 700;
  }

  .action-cards .card p {
    font-size: 0.85rem;
    margin-bottom: 15px;
    line-height: 1.3;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    height: auto;
    min-height: 2.6em;
    width: 100%;
    opacity: 0.85;
  }

  .action-cards .btn-primary {
    width: 100% !important;
    height: 46px !important;
    font-size: 1.05rem !important;
    min-width: unset !important;
    padding: 0 !important;
    border-radius: 14px !important;
    margin: 0 !important;
  }

  /* 详情页卡片保持原样，但覆盖上面的通用card样式 */
  .upload-card,
  .receive-card {
    padding: 25px 20px;
    margin: 10px 0;
    border-radius: 20px;
    max-width: 100%;
  }

  .pickup-code {
    font-size: 3.2rem;
    letter-spacing: 8px;
    margin: 20px 0;
  }

  .code-input-wrapper {
    gap: 8px;
    justify-content: center;
    flex-wrap: wrap;
  }

  .code-box {
    width: 50px;
    height: 60px;
    font-size: 1.5rem;
    border-radius: 12px;
  }

  .btn-primary,
  .card-button {
    width: 180px !important;
    height: 56px !important;
    padding: 0 !important;
    font-size: 1.1rem !important;
    margin: 15px auto;
    border-radius: 50px !important;
  }

  .send-btn,
  .receive-btn {
    width: 100% !important;
    padding: 18px 20px !important;
    font-size: 1.1rem !important;
  }

  /* 文件上传区域 */
  .file-drop-zone {
    padding: 30px 20px;
    min-height: 180px;
  }

  .file-drop-zone.drag-over {
    transform: scale(1.02);
  }

  .file-icon {
    font-size: 2.5rem;
  }

  /* 进度条优化 */
  .progress-container {
    margin: 20px 0;
  }

  .progress-bar {
    height: 8px;
    border-radius: 4px;
  }

  /* 状态指示器 */
  .status-container {
    margin: 20px 0;
    padding: 15px;
    border-radius: 15px;
  }

  .status-indicator {
    width: 70px;
    height: 70px;
    margin: 0 auto 20px;
  }

  /* 文件预览 */
  .file-preview {
    padding: 20px 15px;
    margin: 15px 0;
  }
}

/* === 超小屏幕适配 (小于480px) === */
@media (max-width: 480px) {
  .container {
    padding: 10px;
  }

  .header h1 {
    font-size: 1.8rem;
  }

  .header p {
    font-size: 0.9rem;
  }

  .card,
  .upload-card,
  .receive-card {
    padding: 20px 15px;
    margin: 5px 0;
    border-radius: 15px;
  }

  .pickup-code {
    font-size: 2.5rem;
    letter-spacing: 6px;
  }

  .code-input-wrapper {
    gap: 6px;
  }

  .code-box {
    width: 45px;
    height: 55px;
    font-size: 1.3rem;
    border-radius: 10px;
  }

  .btn-primary,
  .card-button {
    width: 180px !important;
    height: 56px !important;
    padding: 0 !important;
    font-size: 1rem !important;
    border-radius: 50px !important;
  }

  .file-drop-zone {
    padding: 25px 15px;
    min-height: 160px;
  }

  .file-icon {
    font-size: 2rem;
  }

  /* 优化触摸交互 */
  .card-button,
  .btn-primary {
    min-height: 48px; /* iOS推荐的最小触摸区域 */
  }

  .code-box {
    min-height: 48px;
    min-width: 40px;
  }
}

/* === 横屏手机适配 === */
@media (max-width: 768px) and (orientation: landscape) {
  .container {
    padding: 10px 20px;
  }

  .header {
    margin-bottom: 20px;
  }

  .header h1 {
    font-size: 1.8rem;
  }

  .card,
  .upload-card,
  .receive-card {
    padding: 20px 25px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
  }

  .back-link {
    top: 10px;
    left: 10px;
    padding: 10px;
  }
}