/* ===== Reset & Base ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #0a0a0a;
  --color-surface: #141414;
  --color-surface-hover: #1a1a1a;
  --color-border: #262626;
  --color-text: #fafafa;
  --color-text-muted: #a1a1aa;
  --color-text-dimmed: #71717a;
  --color-accent: #3b82f6;
  --color-accent-hover: #2563eb;
  --color-success: #22c55e;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;
  
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  
  --nav-height: 52px;
}

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

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--color-accent-hover);
}

/* ===== App Container ===== */
.app {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 16px;
}

/* ===== Masthead ===== */
.masthead {
  padding: 24px 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 0;
}

.masthead-topline {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.date-picker {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  color: var(--color-text);
  font-size: 14px;
  transition: background 0.2s;
}

.date-picker:hover {
  background: var(--color-surface-hover);
}

.date-picker input[type="date"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.live-status {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--color-text-muted);
}

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

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.masthead-title {
  text-align: center;
  margin-bottom: 20px;
}

.ascii-title {
  font-family: var(--font-mono);
  font-size: 10px;
  line-height: 1.2;
  color: var(--color-accent);
  white-space: pre;
  overflow-x: auto;
}

@media (min-width: 640px) {
  .ascii-title {
    font-size: 14px;
  }
}

.masthead-overview {
  text-align: center;
}

.masthead-overview > p {
  font-size: 15px;
  color: var(--color-text-muted);
  max-width: 700px;
  margin: 0 auto 16px;
  text-align: left;
  white-space: pre-line;
  line-height: 1.8;
}

.digest-facts {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px 20px;
  font-size: 14px;
  color: var(--color-text-dimmed);
}

.digest-facts strong {
  color: var(--color-text);
}

.updated-at {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ===== Topic Navigation ===== */
.topic-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 0;
  margin: 0 -16px;
  overflow: hidden;
}

.topic-nav-track {
  display: flex;
  gap: 4px;
  padding: 10px 16px;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.topic-nav-track::-webkit-scrollbar {
  display: none;
}

.topic-tab {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  font-size: 13px;
  white-space: nowrap;
  transition: all 0.2s;
}

.topic-tab:hover {
  background: var(--color-surface-hover);
  color: var(--color-text);
}

.topic-tab.active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: white;
}

.topic-tab .topic-icon {
  font-size: 14px;
}

.topic-tab .topic-count {
  background: rgba(255, 255, 255, 0.15);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 600;
}

.topic-tab.active .topic-count {
  background: rgba(255, 255, 255, 0.25);
}

/* ===== Loading & Empty State ===== */
.loading, .empty-state {
  text-align: center;
  padding: 60px 20px;
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  margin: 0 auto 16px;
  animation: spin 1s linear infinite;
}

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

.empty-state svg {
  color: var(--color-text-dimmed);
  margin-bottom: 16px;
}

.empty-state h2 {
  font-size: 18px;
  margin-bottom: 8px;
}

.empty-state p {
  color: var(--color-text-muted);
  font-size: 14px;
}

/* ===== Topic Sections ===== */
.topic-sections {
  padding-top: 24px;
}

.topic-section {
  margin-bottom: 32px;
  scroll-margin-top: calc(var(--nav-height) + 16px);
}

.topic-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.topic-title {
  display: flex;
  align-items: center;
  gap: 10px;
}

.topic-title .topic-icon {
  font-size: 24px;
}

.topic-title h2 {
  font-size: 18px;
  font-weight: 600;
}

.topic-badge {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--color-text-muted);
}

/* Topic Lead Item (第一条完整卡片) */
.topic-lead-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 12px;
}

.topic-lead-item .item-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
  font-size: 13px;
}

.topic-lead-item .item-rank {
  background: var(--color-accent);
  color: white;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-weight: 600;
}

.topic-lead-item .item-source {
  color: var(--color-warning);
}

.topic-lead-item .item-category {
  color: var(--color-text-dimmed);
}

.topic-lead-item h3 {
  font-size: 17px;
  line-height: 1.4;
  margin-bottom: 10px;
  font-weight: 600;
}

.topic-lead-item h3 a {
  color: var(--color-text);
}

.topic-lead-item h3 a:hover {
  color: var(--color-accent);
}

.topic-lead-item .summary {
  color: var(--color-text-muted);
  font-size: 14px;
  line-height: 1.7;
  margin-bottom: 14px;
}

.topic-lead-item .item-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: var(--color-text-dimmed);
}

.topic-lead-item .item-footer a {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* Topic Collapsed List (折叠的标题列表) */
.topic-collapsed-list {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.topic-collapsed-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  color: var(--color-text);
  border-bottom: 1px solid var(--color-border);
  transition: background 0.2s;
}

.topic-collapsed-item:last-child {
  border-bottom: none;
}

.topic-collapsed-item:hover {
  background: var(--color-surface-hover);
}

.collapsed-rank {
  color: var(--color-accent);
  font-weight: 600;
  font-size: 13px;
  min-width: 24px;
}

.collapsed-title {
  flex: 1;
  font-size: 14px;
  line-height: 1.4;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.collapsed-source {
  font-size: 12px;
  color: var(--color-text-dimmed);
  white-space: nowrap;
}

.collapsed-arrow {
  color: var(--color-text-dimmed);
  flex-shrink: 0;
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 32px 0;
  margin-top: 24px;
  border-top: 1px solid var(--color-border);
  font-size: 13px;
  color: var(--color-text-dimmed);
}

/* ===== Source Colors ===== */
.source-hackernews { color: #ff6600 !important; }
.source-github { color: #238636 !important; }
.source-arxiv { color: #b31b1b !important; }
.source-rss { color: #ee802f !important; }
.source-producthunt { color: #da552f !important; }
.source-huggingface { color: #ffcc00 !important; }

/* ===== Responsive ===== */
@media (max-width: 640px) {
  .masthead {
    padding: 16px 0;
  }
  
  .masthead-topline {
    flex-direction: column;
    gap: 12px;
  }
  
  .digest-facts {
    flex-direction: column;
    gap: 8px;
  }
  
  .topic-title h2 {
    font-size: 16px;
  }
  
  .topic-lead-item {
    padding: 16px;
  }
  
  .topic-lead-item h3 {
    font-size: 15px;
  }
  
  .collapsed-title {
    font-size: 13px;
  }
  
  .topic-tab {
    padding: 6px 10px;
    font-size: 12px;
  }
  
  .topic-tab .topic-name {
    display: none;
  }
  
  .topic-tab .topic-icon {
    font-size: 16px;
  }
}