:root {
  /* 纯白渐变背景基调 */
  --bg: #ffffff;
  --bg-soft: #f4fdf8;
  --card: rgba(255, 255, 255, 0.95);
  --card-strong: #ffffff;
  --line: #e2e8f0;
  --line-strong: #cbd5e1;
  --text: #1e293b;
  --muted: #64748b;
  
  /* 主强调色：生机勃勃的绿色系列 */
  --accent: #10b981;
  --accent-strong: #059669;
  --accent-deep: #047857;
  --accent-soft: rgba(16, 185, 129, 0.12);
  --accent-glow: rgba(16, 185, 129, 0.2);
  
  /* 辅助色 */
  --warn: #f59e0b;
  --error: #ef4444;
  --success: #10b981;
  --info: #3b82f6;
  --purple: #8b5cf6;
  --pink: #ec4899;
  
  /* 阴影更轻柔 */
  --shadow: 0 4px 20px rgba(16, 185, 129, 0.04);
  --shadow-hover: 0 10px 24px rgba(16, 185, 129, 0.12);
  --image-blur-radius: 18px;
}

* { box-sizing: border-box; }
html { color-scheme: light; }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  /* 纯白到极浅绿的渐变背景 */
  background: linear-gradient(135deg, #ffffff 0%, #f4fdf8 100%);
}

body.has-overlay { overflow: hidden; }
h1, h2, h3, h4, p, ol, ul { margin: 0; }
button, input { font: inherit; }
button { border: 0; outline: none; }

/* 减小页面顶部留白，让内容上提 */
.page-shell {
  width: min(1200px, calc(100% - 24px));
  margin: 0 auto;
  padding: 16px 0 24px;
}

.settings-float {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--accent-soft);
  background: #ffffff;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 80;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease, color 0.2s ease;
}

.settings-float:hover {
  transform: translateY(-2px) rotate(30deg);
  box-shadow: var(--shadow-hover);
  color: var(--accent-strong);
}

.panel-card, .status-card, .warning-item, .task-card, .result-card, 
.detail-section, .chapter-item, .chapter-volume, .detail-source-button, .source-option {
  background: var(--card);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: 12px; /* 减小圆角使其显得更紧凑 */
}

/* 压缩顶部横幅空间 */
.hero-copy {
  padding: 12px 16px;
  background: linear-gradient(135deg, #ffffff, #f0fdf4);
  border: 1px solid #ffffff;
  border-radius: 16px;
  box-shadow: var(--shadow);
}

/* 压缩面板内边距 */
.control-panel, .results-panel, .tasks-panel { padding: 16px; }

.eyebrow {
  display: inline-flex; margin-bottom: 6px; color: var(--accent-deep);
  font-size: 11px; font-weight: 800; letter-spacing: 0.1em;
  text-transform: uppercase; background: var(--accent-soft);
  padding: 2px 10px; border-radius: 999px;
}

h1 { font-size: clamp(20px, 3vw, 28px); font-weight: 800; line-height: 1.2; color: #0f172a; }
h2 { font-size: 16px; font-weight: 700; color: #1e293b; }
h3 { font-size: 14px; font-weight: 700; color: #334155; }

.lead, .panel-hint, .field-label, .page-indicator, .result-author, 
.result-source, .result-extra, .task-meta, .task-progress-text, 
.task-current, .task-message, .detail-author, .detail-source, 
.detail-description, .detail-link { color: var(--muted); line-height: 1.4; font-size: 13px; }

.lead { margin-top: 6px; max-width: 60ch; font-size: 13px; }

.tab-bar {
  display: inline-flex; gap: 4px; margin-top: 12px; padding: 4px;
  background: #ffffff; border: 1px solid var(--accent-soft);
  border-radius: 999px; box-shadow: var(--shadow);
}

.tab-button {
  display: inline-flex; align-items: center; gap: 6px;
  min-height: 32px; padding: 0 16px; border-radius: 999px;
  background: transparent; color: var(--muted); font-weight: 700; font-size: 14px;
  cursor: pointer; transition: all 0.3s ease;
}

.tab-button:hover { color: var(--accent-strong); background: var(--accent-soft); }
.tab-button.is-active {
  color: #fff; background: var(--accent); box-shadow: 0 4px 10px var(--accent-glow);
}

.tab-count, .count-badge, .result-badge, .task-status {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 20px; padding: 0 8px; border-radius: 999px;
  font-size: 11px; font-weight: 800;
}
.tab-count { background: #f1f5f9; color: #475569; }
.tab-button.is-active .tab-count { background: rgba(255, 255, 255, 0.3); color: #fff; }
.count-badge { background: #fee2e2; color: #b91c1c; }
.result-badge { background: #e0e7ff; color: #4338ca; }

.tab-panel { display: none; margin-top: 16px; }
.tab-panel.is-active { display: block; animation: fadeIn 0.3s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: translateY(0); } }

.search-layout { display: flex; flex-direction: column; gap: 16px; }
.control-panel { position: relative; z-index: 10; }
.search-form { display: flex; flex-wrap: wrap; gap: 12px; align-items: flex-end; margin-bottom: 16px; }
.search-field { flex: 1; min-width: 200px; display: flex; flex-direction: column; gap: 6px; }
.feedback-stack, .results-panel, .tasks-panel, .task-list, .detail-content { display: grid; gap: 12px; }

/* 压缩输入框高度 */
.search-input {
  width: 100%; min-height: 40px; padding: 0 16px;
  color: var(--text); background: #ffffff;
  border: 1px solid var(--line-strong); border-radius: 10px;
  font-size: 14px; transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.search-input:focus {
  outline: none; background: #ffffff; border-color: var(--accent);
  box-shadow: 0 4px 12px var(--accent-soft), 0 0 0 1px var(--accent);
  transform: translateY(-1px);
}

/* 按钮全绿且高度压缩 */
.search-button, .download-button {
  min-height: 38px; padding: 0 20px; color: #fff; font-weight: 700; font-size: 14px;
  border-radius: 10px; cursor: pointer; transition: all 0.2s;
  background: var(--accent);
  box-shadow: 0 4px 12px var(--accent-glow); white-space: nowrap;
}
.search-button:hover, .download-button:hover { transform: translateY(-1px); background: var(--accent-strong); box-shadow: 0 6px 16px var(--accent-glow); }

.page-button, .detail-close, .detail-source-button {
  min-height: 30px; padding: 0 12px; border-radius: 8px; cursor: pointer;
  color: var(--accent-deep); background: #ffffff; border: 1px solid var(--line);
  font-weight: 600; font-size: 13px; transition: all 0.2s ease;
}
.page-button:hover, .detail-close:hover {
  border-color: var(--accent); color: var(--accent); background: var(--accent-soft);
}
.tool-button {
  min-height: 30px; padding: 0 16px; border-radius: 999px;
  cursor: pointer; font-weight: 600; font-size: 13px; transition: all 0.2s ease;
  color: var(--accent-deep); background: var(--accent-soft); border: 1px solid transparent;
}

.tool-button:hover {
  background: var(--accent); color: #ffffff; box-shadow: 0 4px 10px var(--accent-glow);
  transform: translateY(-1px);
}

.tool-button.is-ghost {
  color: var(--muted); background: #f1f5f9; border: 1px solid var(--line);
}

.tool-button.is-ghost:hover {
  background: #fee2e2; color: var(--error); border-color: #fca5a5; box-shadow: none;
}
.search-button:disabled, .download-button:disabled, .page-button:disabled { opacity: 0.5; cursor: not-allowed; transform: none; box-shadow: none; }

.selection-toolbar, .results-tools, .pagination, .panel-header, .results-head, 
.task-head, .task-messages, .detail-meta, .detail-actions, .detail-source-switch, .detail-links { display: flex; flex-wrap: wrap; gap: 8px; }
.panel-header, .results-head, .task-head { justify-content: space-between; align-items: flex-end; margin-bottom: 6px; }

/* 压缩标签面板 */
.source-tag-panel {
  display: grid; gap: 10px; margin-bottom: 16px; padding: 14px 16px;
  border: 1px solid #ffffff;
  border-radius: 12px;
  background: linear-gradient(135deg, #ffffff 0%, var(--bg-soft) 100%);
  box-shadow: var(--shadow);
}
.source-tag-panel-head { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-bottom: 2px; min-height: 30px; }
.source-tag-filters { display: flex; flex-wrap: wrap; gap: 6px; }

/* 压缩具体标签 */
.source-tag-filter {
  display: inline-flex; align-items: center; gap: 6px; min-height: 26px; padding: 0 10px;
  border-radius: 999px; border: 1px solid var(--line); background: #ffffff; color: var(--muted);
  cursor: pointer; font-size: 12px; font-weight: 600; transition: all 0.2s ease;
}
.source-tag-filter:hover { border-color: var(--accent); color: var(--accent-deep); background: var(--bg-soft); }
.source-tag-filter.is-active {
  color: #ffffff; border-color: var(--accent); background: var(--accent);
  box-shadow: 0 4px 10px var(--accent-glow);
}
.source-tag-filter-count {
  display: inline-flex; align-items: center; justify-content: center; min-width: 18px; min-height: 18px;
  padding: 0 4px; border-radius: 999px; background: rgba(0,0,0,0.06); color: inherit; font-size: 10px; font-weight: 800;
}
.source-tag-filter.is-active .source-tag-filter-count { background: rgba(255, 255, 255, 0.2); }

/* 极致压缩渠道格子 */
.source-selector { display: grid; grid-template-columns: repeat(auto-fill, minmax(130px, 1fr)); gap: 8px; }
.source-option {
  display: flex; flex-direction: column; align-items: flex-start; justify-content: flex-start; gap: 6px;
  min-height: 85px; /* 高度从 138px 大幅缩小 */
  padding: 10px; text-align: left; border-radius: 10px;
  cursor: pointer; border: 1px solid var(--line); background: #fff; transition: all 0.2s;
}
.source-option:hover { transform: translateY(-2px); border-color: var(--accent); box-shadow: var(--shadow-hover); }
.source-option.is-selected {
  background: var(--bg-soft);
  border-color: var(--accent);
  box-shadow: 0 4px 12px var(--accent-glow);
}
.source-option-title {
  font-size: 13px; font-weight: 700; line-height: 1.2; color: #0f172a;
  display: -webkit-box; overflow: hidden; -webkit-box-orient: vertical; -webkit-line-clamp: 1; /* 标题仅占1行 */
  width: 100%;
}
.source-option-key {
  display: inline-flex; align-items: center; min-height: 20px; padding: 0 6px; border-radius: 6px;
  background: var(--accent-soft); color: var(--accent-deep);
  font-family: "JetBrains Mono", Consolas, monospace;
  font-size: 10px; font-weight: 600;
}
.source-option-tags { display: flex; flex-wrap: wrap; gap: 4px; margin-top: auto; }
.source-option-tag {
  display: inline-flex; align-items: center; min-height: 18px; padding: 0 6px; border-radius: 4px;
  border: 1px solid var(--line); background: #f8fafc; color: var(--muted); font-size: 10px;
}
.source-option.is-selected .source-option-tag { border-color: var(--accent-soft); background: #fff; color: var(--accent-deep); }

.site-warning-stack { margin: 12px 0; display: grid; gap: 8px; }
.site-warning-card {
  display: flex; flex-direction: column; gap: 6px; padding: 12px 14px;
  border-radius: 10px; border: 1px solid var(--line); background: #fff;
}
.site-warning-card.site-warning-danger { border-left: 4px solid #ef4444; }
.site-warning-card.site-warning-info { border-left: 4px solid var(--accent); }
.site-warning-card.site-warning-config { border-left: 4px solid #0ea5e9; }
.site-warning-head { display: flex; align-items: center; gap: 6px; font-weight: 600; font-size: 13px; }
.site-warning-icon { font-size: 16px; }
.site-warning-message { margin: 0; font-size: 13px; }
.site-warning-detail { margin: 0; font-size: 12px; color: var(--muted); }
.site-warning-action {
  display: inline-flex; align-self: flex-start; padding: 2px 8px; font-size: 12px;
  border-radius: 6px; border: 1px solid var(--accent-soft);
  color: var(--accent); text-decoration: none; font-weight: 600;
}

.site-config-overlay[hidden] { display: none; }
.site-config-overlay { position: fixed; inset: 0; z-index: 70; }
.site-config-backdrop { position: absolute; inset: 0; background: rgba(15, 23, 42, 0.4); backdrop-filter: blur(4px); }
.site-config-modal {
  position: relative; width: min(760px, calc(100vw - 24px)); max-height: calc(100vh - 24px);
  overflow: auto; margin: 12px auto; padding: 16px; border-radius: 16px;
  background: #fff; box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.site-config-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.settings-layout { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.config-section-card { border: 1px solid var(--line); border-radius: 10px; padding: 12px; background: #f8fafc; }
.config-section-head { display: grid; gap: 4px; margin-bottom: 8px; }

.site-config-form { display: grid; gap: 10px; }

@media (max-width: 960px) { .settings-layout { grid-template-columns: 1fr; } }

.site-config-check { display: inline-flex; align-items: center; gap: 6px; font-size: 13px; color: var(--text); }

.input-icon-wrap { position: relative; display: flex; align-items: center; width: 100%; }
.input-icon-wrap .search-input { padding-right: 36px; width: 100%; }
.input-icon-btn {
  position: absolute; right: 8px; background: none; border: none;
  color: var(--muted); cursor: pointer; padding: 4px; display: flex;
  align-items: center; justify-content: center; outline: none; transition: color 0.2s;
}
.input-icon-btn:hover { color: var(--accent); }

.range-wrap { display: flex; align-items: center; gap: 10px; width: 100%; min-height: 38px; }
.search-input.slider {
  -webkit-appearance: none; flex: 1; height: 4px; border: none;
  background: var(--line); border-radius: 999px; padding: 0;
}
.search-input.slider:focus { box-shadow: none; }
.search-input.slider::-webkit-slider-thumb {
  -webkit-appearance: none; width: 16px; height: 16px; border-radius: 50%;
  background: var(--accent); cursor: pointer; transition: transform 0.2s ease;
}
.search-input.slider::-webkit-slider-thumb:hover { transform: scale(1.15); }
.range-val { font-weight: 700; color: var(--accent-deep); min-width: 28px; text-align: right; font-size: 13px; }

.site-config-textarea {
  width: 100%; border-radius: 8px; border: 1px solid var(--line);
  padding: 8px 10px; font: inherit; resize: vertical; font-size: 13px;
}
.site-config-textarea:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.site-config-actions { display: flex; justify-content: flex-end; margin-top: 6px; }

.status-card { padding: 10px 14px; font-weight: 600; font-size: 13px; color: var(--accent-deep); background: var(--bg-soft); border-color: var(--accent-soft); }
.warning-list { display: grid; gap: 8px; }
.warning-list.is-empty { display: none; }
.warning-item { padding: 10px 14px; font-size: 13px; color: var(--error); background: #fef2f2; border-color: #fecaca; border-radius: 8px;}

/* 搜索结果更紧凑 */
.results-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 12px; padding-top: 6px; }
.result-card { display: flex; flex-direction: column; gap: 8px; padding: 10px; background: #fff; transition: all 0.2s ease; }
.result-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); border-color: var(--accent); }

.result-cover-button { position: relative; width: 100%; padding: 0; background: transparent; cursor: pointer; border-radius: 8px; overflow: hidden; }
.result-cover { display: block; width: 100%; aspect-ratio: 3 / 4; object-fit: cover; transition: transform 0.3s ease; background: #f8fafc; }
.result-card:hover .result-cover { transform: scale(1.03); }

body.web-images-blurred .result-cover,
body.web-images-blurred .detail-cover {
  filter: blur(var(--image-blur-radius));
  transform: scale(1.04);
  transform-origin: center;
  clip-path: inset(0 round 10px);
}

body.web-images-blurred .result-card:hover .result-cover {
  transform: scale(1.07);
}

.result-cover-overlay {
  position: absolute; bottom: 0; left: 0; width: 100%; padding: 8px 0; text-align: center;
  color: #fff; font-size: 12px; font-weight: 700; background: rgba(16, 185, 129, 0.9);
  backdrop-filter: blur(4px); transform: translateY(100%); transition: transform 0.2s ease;
}
.result-card:hover .result-cover-overlay { transform: translateY(0); }

.result-body { display: flex; flex-direction: column; gap: 4px; flex: 1; }
.result-title { display: -webkit-box; overflow: hidden; min-height: 38px; font-size: 14px; font-weight: 600; line-height: 1.35; -webkit-box-orient: vertical; -webkit-line-clamp: 2; color: #0f172a; margin-bottom: 2px;}
.result-title-link { color: inherit; text-decoration: none; }
.result-title-link:hover { color: var(--accent); text-decoration: underline; }
.result-author, .result-source, .result-extra { font-size: 11px; color: var(--muted); }

.task-card { 
  padding: 14px; background: #fff; border-radius: 12px;
  border-left: 4px solid var(--accent); transition: all 0.2s ease;
}
.task-card:hover { transform: translateY(-1px); box-shadow: var(--shadow-hover); }
.task-title { font-weight: 700; font-size: 14px; color: #1e293b; margin-bottom: 4px; }
.status-running { background: #eff6ff; color: #2563eb; }
.status-completed { background: #ecfdf5; color: #10b981; border-left-color: #10b981; }
.status-failed { background: #fef2f2; color: #ef4444; border-left-color: #ef4444; }
.status-queued { background: #fdf4ff; color: #d946ef; border-left-color: #d946ef; }

.task-progress { display: flex; flex-direction: column; gap: 6px; margin-top: 10px; }
.task-progress-bar { width: 100%; height: 6px; border-radius: 999px; background: #f1f5f9; overflow: hidden; }
.task-progress-fill { height: 100%; border-radius: 999px; background: var(--accent); transition: width 0.4s ease; }
.task-card.is-completed .task-progress-fill { background: var(--success); }
.task-card.is-failed .task-progress-fill { background: var(--error); }

.file-list { margin: 10px 0 0; padding: 10px; background: #f8fafc; border-radius: 6px; color: var(--info); border: 1px solid #e2e8f0; }    
.file-download-link { color: var(--accent-deep); text-decoration: none; font-weight: 600; font-size: 13px; display: inline-flex; align-items: center; gap: 6px; }
.file-download-link:hover { text-decoration: underline; color: var(--accent); }
.file-download-link::before { content: '📦'; font-size: 12px; }

.empty-state, .empty-inline {
  padding: 24px 16px; text-align: center; color: var(--muted); background: #f8fafc;
  border: 1px dashed var(--line-strong); border-radius: 12px; grid-column: 1 / -1; font-size: 13px;
}
.empty-inline { padding: 16px; }
.empty-state-compact { padding: 16px; }

.detail-overlay[hidden] { display: none; }
.detail-overlay { position: fixed; inset: 0; z-index: 60; }
.detail-backdrop { position: absolute; inset: 0; background: rgba(15, 23, 42, 0.4); backdrop-filter: blur(4px); animation: fadeIn 0.3s ease; }
.detail-panel {
  position: relative; margin-left: auto; width: min(600px, 100vw); height: 100vh;
  padding: 20px 24px 30px; overflow-y: auto; background: #ffffff;
  box-shadow: -10px 0 40px rgba(0, 0, 0, 0.1); animation: slideIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}
@keyframes slideIn { from { transform: translateX(100%); } to { transform: translateX(0); } }

.detail-topbar { display: flex; justify-content: flex-end; margin-bottom: 16px; position: sticky; top: -10px; z-index: 10; }
.detail-close { min-width: 60px; background: #f1f5f9; border: none; color: #475569; }
.detail-close:hover { background: #e2e8f0; color: #0f172a; }

.detail-hero { display: grid; grid-template-columns: 130px minmax(0, 1fr); gap: 20px; align-items: start; }
.detail-cover { width: 100%; aspect-ratio: 3 / 4; object-fit: cover; border-radius: 10px; box-shadow: var(--shadow); border: 1px solid var(--line); }

.detail-summary { display: flex; flex-direction: column; gap: 8px; }
.detail-title { font-size: clamp(18px, 2vw, 24px); font-weight: 700; line-height: 1.3; color: #0f172a; }
.detail-title-link { color: inherit; text-decoration: none; }
.detail-title-link:hover { color: var(--accent-strong); text-decoration: underline; }
.detail-source-button.is-active { color: #fff; background: var(--accent); border-color: var(--accent); box-shadow: 0 4px 10px var(--accent-glow); }
.detail-actions { margin-top: auto; padding-top: 10px; }
.detail-link { color: var(--accent); font-weight: 600; }

.detail-section { padding: 16px; margin-top: 16px; background: #f8fafc; border: none; }
.detail-description { white-space: pre-line; font-size: 13px; line-height: 1.6; color: #475569; }

.chapter-list { display: grid; gap: 6px; max-height: 400px; overflow-y: auto; padding-right: 6px; }
.chapter-volume { padding: 8px 10px; color: var(--accent-deep); font-size: 13px; font-weight: 700; background: var(--bg-soft); border-radius: 6px; margin-top: 6px; }
.chapter-item { display: grid; grid-template-columns: 40px minmax(0, 1fr); gap: 10px; padding: 8px 10px; background: #ffffff; border-radius: 6px; border: 1px solid var(--line); transition: border-color 0.2s; }
.chapter-item:hover { border-color: var(--accent); box-shadow: 0 2px 6px var(--accent-soft); }
.chapter-index { display: inline-flex; align-items: center; justify-content: center; height: 20px; border-radius: 4px; font-size: 11px; font-weight: 700; color: var(--accent-deep); background: var(--accent-soft); }
.chapter-title { line-height: 1.4; font-size: 13px; color: #334155; }
.chapter-title-link { color: #0f172a; text-decoration: none; transition: color 0.2s ease; }
.chapter-title-link:hover { color: var(--accent-strong); text-decoration: underline; }

@media (max-width: 768px) {
  .page-shell { width: 100%; padding: 12px 12px 24px; }
  .hero-copy, .control-panel, .results-panel, .tasks-panel { padding: 12px; border-radius: 12px; }
  .search-form { flex-direction: column; align-items: stretch; gap: 10px; }
  .search-button { width: 100%; }
  .source-selector { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .tab-bar { flex-direction: row; width: 100%; }
  .tab-button { flex: 1; justify-content: center; padding: 0 10px; font-size: 13px; }
  .results-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
  .result-card { padding: 8px; border-radius: 10px; }
  .result-title { font-size: 13px; }
  .detail-panel { width: 100vw; padding: 16px; }
  .detail-hero { grid-template-columns: 1fr; gap: 16px; }
  .detail-cover { max-width: 120px; margin: 0 auto; }
  .detail-actions .download-button { width: 100%; }
}

@media (max-width: 400px) {
  .results-grid { grid-template-columns: 1fr; }
  .result-cover { max-width: 160px; margin: 0 auto; }
}

::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 999px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-soft); }

.back-to-top {
  position: fixed; bottom: 24px; right: 24px; width: 40px; height: 40px;
  border-radius: 50%; background: var(--accent);
  color: white; border: none; box-shadow: 0 4px 12px var(--accent-glow);
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  transition: all 0.3s ease;
  opacity: 0; visibility: hidden; transform: translateY(20px) scale(0.9); z-index: 50;
}
.back-to-top.is-visible { opacity: 1; visibility: visible; transform: translateY(0) scale(1); }
.back-to-top:hover { transform: translateY(-3px) scale(1.05); box-shadow: 0 8px 16px var(--accent-glow); background: var(--accent-strong); }
.back-to-top svg { width: 18px; height: 18px; }
@media (max-width: 768px) {
  .back-to-top { bottom: 16px; right: 16px; width: 36px; height: 36px; }
}