/* ========== 配色系统 ========== */
:root {
  /* 浅色 - 冷白底 + 蓝色强调 */
  --bg: #f5f7fa;
  --bg-card: #ffffff;
  --bg-elevated: #eef1f6;
  --text: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-soft: rgba(37, 99, 235, 0.10);
  --accent-text: #ffffff;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --btn-bg: #eef1f6;
  --btn-text: #334155;
  --btn-hover: #e2e8f0;
  --btn-shadow: #d1d8e0;
  --input-bg: #ffffff;
  --input-border: #e2e8f0;
  --modal-overlay: rgba(15, 23, 42, 0.3);
  --preview-bg: #f1f5f9;
  --preview-border: #e2e8f0;
  --empty-text: #94a3b8;
  --danger: #ef4444;
  --danger-hover: #dc2626;
  --tag-bg: #eff6ff;
  --tag-text: #2563eb;
  --shadow-sm: 0 1px 3px rgba(37, 99, 235, 0.06);
  --shadow-md: 0 4px 16px rgba(37, 99, 235, 0.08);
  --shadow-lg: 0 12px 40px rgba(37, 99, 235, 0.10);
  --shadow-card: 0 2px 20px rgba(15, 23, 42, 0.05);
}

[data-theme="dark"] {
  /* 深色 - 深蓝黑底 + 天蓝强调 */
  --bg: #0c0f1a;
  --bg-card: #141827;
  --bg-elevated: #1c2133;
  --text: #e8ecf4;
  --text-secondary: #b4bdd0;
  --text-muted: #6b7a99;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --accent-soft: rgba(59, 130, 246, 0.12);
  --accent-text: #ffffff;
  --border: #232940;
  --border-strong: #343d5c;
  --btn-bg: #1c2133;
  --btn-text: #b4bdd0;
  --btn-hover: #232940;
  --btn-shadow: #080a12;
  --input-bg: #0e1120;
  --input-border: #232940;
  --modal-overlay: rgba(0, 0, 0, 0.6);
  --preview-bg: #0e1120;
  --preview-border: #232940;
  --empty-text: #3e4a66;
  --danger: #f87171;
  --danger-hover: #fca5a5;
  --tag-bg: rgba(59, 130, 246, 0.12);
  --tag-text: #3b82f6;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.4);
  --shadow-card: 0 2px 30px rgba(0, 0, 0, 0.3);
}

/* ========== 基础重置 ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px;
  transition: background 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
}

/* ========== 主题切换 ========== */
.theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 100;
  width: 44px;
  height: 44px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s, box-shadow 0.2s;
  font-size: 1.2rem;
}

.theme-toggle:hover {
  transform: scale(1.06);
  box-shadow: var(--shadow-md);
}

.toggle-icon { display: none; line-height: 1; }
[data-theme="dark"] .toggle-icon.sun { display: block; }
[data-theme="light"] .toggle-icon.moon { display: block; }

/* ========== 工具卡片 ========== */
.tool-card {
  max-width: 920px;
  width: 100%;
  background: var(--bg-card);
  border-radius: 24px;
  padding: 28px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-card);
  animation: fadeUp 0.4s ease;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ========== 卡片头部 ========== */
.card-header {
  text-align: center;
  margin-bottom: 24px;
}

.card-title {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--accent), #38bdf8);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.card-desc {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 4px;
}

/* ========== 工具栏 ========== */
.toolbar {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 16px;
}

/* ========== 按钮系统 ========== */
.btn {
  height: 50px;
  border-radius: 14px;
  font-size: 0.95rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: all 0.15s ease;
  user-select: none;
  position: relative;
  overflow: hidden;
}

.btn-emoji { font-size: 1.15rem; line-height: 1; }

.btn:hover:not(:disabled) { transform: translateY(-1px); }
.btn:active:not(:disabled) { transform: translateY(0); }
.btn:disabled { opacity: 0.35; cursor: not-allowed; }

/* 描边按钮 */
.btn-outline {
  background: var(--btn-bg);
  color: var(--btn-text);
  border-color: var(--border);
  box-shadow: var(--shadow-sm);
}
.btn-outline:hover:not(:disabled) {
  background: var(--btn-hover);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

/* 强调按钮 */
.btn-accent {
  background: var(--accent);
  color: var(--accent-text);
  border-color: var(--accent);
  box-shadow: 0 2px 12px var(--accent-soft);
}
.btn-accent:hover:not(:disabled) {
  background: var(--accent-hover);
  box-shadow: 0 4px 20px var(--accent-soft);
}

/* 幽灵按钮 */
.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border-color: var(--border);
}
.btn-ghost:hover:not(:disabled) {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: var(--accent);
}

/* 危险按钮 */
.btn-danger {
  background: transparent;
  color: var(--danger);
  border-color: var(--danger);
}
.btn-danger:hover:not(:disabled) {
  background: var(--danger);
  color: #fff;
}

.btn-small {
  height: 38px;
  font-size: 0.85rem;
  padding: 0 16px;
  border-radius: 11px;
}

.flex-1 { flex: 1; }

/* ========== 进度条 ========== */
.progress-section {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
  padding: 0 2px;
}

.progress-section progress {
  flex: 1;
  height: 6px;
  border: none;
  border-radius: 3px;
  background: var(--bg-elevated);
  overflow: hidden;
}

.progress-section progress::-webkit-progress-bar {
  background: var(--bg-elevated);
  border-radius: 3px;
}

.progress-section progress::-webkit-progress-value {
  background: linear-gradient(90deg, var(--accent), #38bdf8);
  border-radius: 3px;
  transition: width 0.2s ease;
}

.progress-section progress::-moz-progress-bar {
  background: linear-gradient(90deg, var(--accent), #38bdf8);
  border-radius: 3px;
}

#progressText {
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 700;
  min-width: 38px;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* ========== 文件信息 ========== */
.file-info {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 6px 0 10px;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.file-tag {
  display: inline-block;
  background: var(--tag-bg);
  color: var(--tag-text);
  padding: 2px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

/* ========== 预览区域 ========== */
.preview-area {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--preview-bg);
  border: 2px dashed var(--preview-border);
  border-radius: 18px;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: border-color 0.2s, background 0.2s;
}

.preview-area.drag-over {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.preview-empty {
  text-align: center;
  padding: 24px;
}

.empty-icon {
  font-size: 2.4rem;
  margin-bottom: 10px;
  opacity: 0.5;
}

.empty-title {
  color: var(--text-muted);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

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

.preview-media {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  display: none;
}

.preview-media.active { display: block; }

#previewCanvas { width: 100%; height: 100%; }

/* ========== 视频进度 ========== */
.video-progress-bar {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--border);
  cursor: pointer;
}

.video-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #38bdf8);
  border-radius: 2px;
  width: 0%;
  transition: width 0.1s linear;
}

/* ========== 导航行 ========== */
.nav-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}

.nav-counter {
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
  min-width: 60px;
  text-align: center;
  font-variant-numeric: tabular-nums;
}

/* ========== 弹窗 ========== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--modal-overlay);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  backdrop-filter: blur(8px);
}

.modal-overlay.open { display: flex; }

/* ========== 图片放大预览 ========== */
.lightbox-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.88);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  cursor: zoom-out;
  animation: fadeIn 0.15s ease;
}
.lightbox-overlay.open { display: flex; }

.lightbox-img {
  max-width: 95vw;
  max-height: 95vh;
  object-fit: contain;
  border-radius: 4px;
  box-shadow: 0 0 40px rgba(0, 0, 0, 0.5);
  user-select: none;
  -webkit-user-drag: none;
}

#previewImg.active { cursor: zoom-in; }

@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

.param-window {
  background: var(--bg-card);
  border-radius: 22px;
  padding: 28px;
  width: 92%;
  max-width: 460px;
  max-height: 90vh;
  overflow-y: auto;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  animation: modalIn 0.2s ease;
}

@keyframes modalIn {
  from { opacity: 0; transform: scale(0.96) translateY(8px); }
  to   { opacity: 1; transform: scale(1) translateY(0); }
}

.param-window h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 20px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

.param-row {
  margin-bottom: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.param-row > label {
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.param-row input[type="text"],
.param-row input[type="number"] {
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  color: var(--text);
  padding: 10px 14px;
  border-radius: 11px;
  font-size: 0.95rem;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.param-row input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.radio-group {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.radio-group label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: color 0.15s;
}

.radio-group label:hover { color: var(--accent); }
.radio-group input[type="radio"] { accent-color: var(--accent); width: 16px; height: 16px; }

.modal-buttons {
  display: flex;
  gap: 10px;
  margin-top: 22px;
}

/* ========== 导出格式 ========== */
.export-format-row {
  display: flex;
  align-items: center;
  gap: 12px;
}

.export-format-row select {
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  color: var(--text);
  padding: 10px 16px;
  border-radius: 11px;
  font-size: 0.9rem;
  outline: none;
  width: 100%;
  transition: border-color 0.15s;
}

.export-format-row select:focus { border-color: var(--accent); }

.hint-text {
  color: var(--text-muted);
  font-size: 0.85rem;
  padding: 4px 0;
}

/* ========== 加载指示 ========== */
.loading-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  border-radius: 18px;
  z-index: 10;
  backdrop-filter: blur(2px);
}

.loading-overlay.active { display: flex; }

.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid rgba(255, 255, 255, 0.15);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.loading-text { color: #fff; font-size: 0.85rem; font-weight: 500; }

@keyframes spin { to { transform: rotate(360deg); } }

/* ========== 响应式 ========== */
@media (min-width: 750px) {
  body { padding: 32px 24px; }

  .toolbar {
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
  }

  .tool-card {
    padding: 36px;
    border-radius: 28px;
  }

  .btn { height: 54px; font-size: 1rem; }

  .card-title { font-size: 1.8rem; }
}

@media (max-width: 400px) {
  body { padding: 12px 8px; }

  .tool-card { padding: 18px; border-radius: 20px; }
  .btn { height: 44px; font-size: 0.9rem; }
  .btn-small { height: 34px; font-size: 0.8rem; padding: 0 12px; }
  .param-window { padding: 22px; border-radius: 18px; }
  .preview-area { aspect-ratio: 4 / 3; }
  .card-title { font-size: 1.3rem; }
}