:root {
  --bg: #f8fafc;
  --bg-subtle: #f1f5f9;
  --panel: #ffffff;
  --panel-border: #e2e8f0;
  --text: #0f172a;
  --text-secondary: #475569;
  --muted: #64748b;
  --accent: #4f46e5;
  --accent-hover: #4338ca;
  --accent-soft: #eef2ff;
  --accent-soft-hover: #e0e7ff;
  --danger: #dc2626;
  --danger-bg: #fef2f2;
  --danger-border: #fecaca;
  --warning-bg: #fffbeb;
  --warning-border: #fde68a;
  --warning-text: #92400e;
  --success: #059669;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
  --radius: 8px;
  --radius-lg: 12px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* Layout */
.shell {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px 48px;
}

/* Topbar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 24px;
  height: 56px;
  background: var(--panel);
  border-bottom: 1px solid var(--panel-border);
  position: sticky;
  top: 0;
  z-index: 50;
}

.brand { display: flex; align-items: center; gap: 10px; }
.brand-kicker { display: none; }
.brand-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
}
.brand-title:hover { text-decoration: none; color: var(--accent); }

.nav { display: flex; align-items: center; gap: 2px; }
.nav a {
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: background 120ms, color 120ms;
}
.nav a:hover { background: var(--bg-subtle); color: var(--text); text-decoration: none; }
.nav a.active { background: var(--accent-soft); color: var(--accent); }
.nav .logout-btn {
  background: none;
  border: 1px solid var(--panel-border);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  padding: 4px 12px;
  min-height: 0;
  height: 32px;
  border-radius: 6px;
  cursor: pointer;
  box-shadow: none;
  margin-left: 8px;
}
.nav .logout-btn:hover { background: var(--bg-subtle); transform: none; }

/* Page header */
.page-header {
  padding: 24px 0 16px;
}
.page-header h1 {
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 4px;
  letter-spacing: -0.02em;
}
.page-header p { color: var(--muted); margin: 0; }
.page-header-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

/* Panels */
.panel {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-sm);
}

/* Grids */
.grid { margin-bottom: 20px; }
.grid.two-up {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.grid.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
}

/* Stat cards */
.stat-card {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.stat-card span { font-size: 13px; color: var(--muted); font-weight: 500; }
.stat-card strong { font-size: 28px; font-weight: 700; letter-spacing: -0.02em; }
.compact-stat strong { font-size: 22px; }

/* Buttons */
button, .button-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 36px;
  padding: 0 16px;
  border: none;
  border-radius: 6px;
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: background 120ms, transform 80ms;
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow-sm);
}
button:hover, .button-link:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  text-decoration: none;
  color: #fff;
}
.button-link-secondary {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--panel-border);
  box-shadow: var(--shadow-sm);
}
.button-link-secondary:hover {
  background: var(--bg-subtle);
  color: var(--text);
}

/* Forms */
label {
  display: grid;
  gap: 6px;
  margin-bottom: 14px;
}
label span {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
}

input, textarea, select {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  font: inherit;
  font-size: 14px;
  color: var(--text);
  background: var(--panel);
  transition: border-color 120ms, box-shadow 120ms;
}
input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
textarea { resize: vertical; }

.form-card { max-width: 480px; }
.form-card h1 { font-size: 18px; font-weight: 700; margin: 0 0 16px; }

/* Section headers */
.section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}
.section-head h2, .section-head h3 { margin: 0; font-size: 15px; font-weight: 700; }
.section-head a { font-size: 13px; }
.section-head span { font-size: 13px; color: var(--muted); }

/* Eyebrow */
.eyebrow {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: 2px;
}

/* Tables */
.table { width: 100%; border-collapse: collapse; font-size: 13px; }
.table th, .table td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid var(--panel-border);
}
.table th { font-weight: 600; color: var(--muted); font-size: 12px; text-transform: uppercase; letter-spacing: 0.04em; }
.table tbody tr:hover { background: var(--bg-subtle); }

/* Lists */
.stack-list { list-style: none; padding: 0; margin: 0; }
.stack-list li {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding: 10px 0;
  font-size: 13px;
}
.bordered-list li { border-bottom: 1px solid var(--panel-border); }
.bordered-list li:last-child { border-bottom: none; }
.stack-list li strong { min-width: 100px; font-weight: 600; color: var(--text); }
.stack-list li span { color: var(--muted); }

/* Notices */
.notice {
  padding: 10px 14px;
  margin-bottom: 16px;
  border-radius: var(--radius);
  font-size: 13px;
  font-weight: 500;
}
.notice.warning {
  background: var(--warning-bg);
  border: 1px solid var(--warning-border);
  color: var(--warning-text);
}
.notice.danger {
  background: var(--danger-bg);
  border: 1px solid var(--danger-border);
  color: var(--danger);
}

.empty-state { color: var(--muted); margin: 0; font-size: 13px; }
.empty-panel {
  padding: 20px;
  border: 1px dashed var(--panel-border);
  border-radius: var(--radius);
  background: var(--bg-subtle);
  text-align: center;
}
.empty-panel p { color: var(--muted); font-size: 13px; margin: 0 0 10px; }

/* Inbox workspace */
.workspace-hero {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 20px;
  align-items: start;
  margin-bottom: 20px;
}
.workspace-stats {
  display: flex;
  gap: 16px;
}
.workspace-stats .stat-card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 14px 18px;
}

.hero { margin-bottom: 20px; }
.hero-copy { display: none; }
.hero-actions { display: flex; gap: 8px; margin-top: 12px; }
.panel-hero {
  background: var(--panel);
}

.section-head-tight { margin-bottom: 10px; }

/* Pane summary */
.pane-summary {
  padding: 8px 12px;
  margin-bottom: 10px;
  border-radius: 6px;
  background: var(--bg-subtle);
  font-size: 13px;
}
.pane-summary strong { font-weight: 600; display: block; }
.pane-summary span { color: var(--muted); font-size: 12px; }

/* Selection cards */
.selection-list, .message-list { display: grid; gap: 6px; }

.selection-card, .message-card {
  display: grid;
  gap: 4px;
  padding: 10px 12px;
  border-radius: 6px;
  border: 1px solid transparent;
  background: var(--panel);
  text-decoration: none;
  transition: background 100ms, border-color 100ms;
  font-size: 13px;
}
.selection-card:hover, .message-card:hover {
  background: var(--bg-subtle);
  text-decoration: none;
}
.selection-card.is-active, .message-card.is-active {
  background: var(--accent-soft);
  border-color: var(--accent);
}
.selection-card strong, .message-card strong { color: var(--text); font-weight: 600; font-size: 13px; }
.selection-card span, .message-card span { color: var(--muted); font-size: 12px; }

.message-card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 8px;
}
.message-card-top time { color: var(--muted); font-size: 12px; white-space: nowrap; }
.message-sender { font-size: 12px; color: var(--text-secondary); }
.message-preview { font-size: 12px; color: var(--muted); line-height: 1.5; }

/* Inbox layout */
.inbox-layout {
  display: grid;
  grid-template-columns: 200px 240px 300px minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  margin-bottom: 20px;
}

.inbox-pane {
  max-height: calc(100vh - 140px);
  overflow-y: auto;
}

.inbox-reader { display: grid; gap: 16px; }

/* Reader */
.reader-header {
  padding-bottom: 14px;
  border-bottom: 1px solid var(--panel-border);
}
.reader-header h3 { margin: 0 0 8px; font-size: 18px; font-weight: 700; }

.reader-meta { display: flex; flex-wrap: wrap; gap: 6px; }
.reader-meta span {
  display: inline-flex;
  align-items: center;
  height: 26px;
  padding: 0 10px;
  border-radius: 999px;
  background: var(--bg-subtle);
  border: 1px solid var(--panel-border);
  font-size: 12px;
  color: var(--text-secondary);
}

.reader-body { display: grid; gap: 16px; }
.reader-card { display: grid; gap: 8px; }
.reader-card h3 { margin: 0; font-size: 14px; font-weight: 700; }

.mail-body {
  margin: 0;
  max-height: 600px;
  overflow: auto;
  padding: 14px;
  border-radius: var(--radius);
  background: var(--bg-subtle);
  border: 1px solid var(--panel-border);
  white-space: pre-wrap;
  word-break: break-word;
  font-size: 13px;
  line-height: 1.7;
  font-family: "SF Mono", "Cascadia Code", "Consolas", monospace;
}
.mail-headers { max-height: 260px; font-size: 12px; }

.mail-frame {
  width: 100%;
  min-height: 500px;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  background: #fff;
}

/* Login */
.login-hero {
  display: grid;
  grid-template-columns: 1fr;
  justify-items: center;
  align-content: center;
  min-height: calc(100vh - 56px);
  padding: 24px;
}
.login-hero .panel-hero { display: none; }
.login-hero .form-card {
  width: 100%;
  max-width: 380px;
}

/* Checklist panel */
.checklist h2 { font-size: 15px; font-weight: 700; margin: 0 0 12px; }

/* Hint panel */
.hint-panel {
  background: var(--accent-soft);
  border-color: var(--accent-soft-hover, #c7d2fe);
}
.hint-panel h2 { font-size: 15px; font-weight: 700; margin: 0 0 8px; }
.hint-panel p { color: var(--text-secondary); font-size: 13px; margin: 0; }

/* Detail pages */
.detail-head { margin-bottom: 20px; }
.detail-head h1 { font-size: 20px; font-weight: 700; margin: 0 0 4px; }
.detail-head p { margin: 0; }
.detail-meta { display: flex; gap: 12px; margin-top: 8px; flex-wrap: wrap; }
.detail-meta span { font-size: 13px; color: var(--muted); }

/* Responsive */
@media (max-width: 1280px) {
  .inbox-layout { grid-template-columns: repeat(2, 1fr); }
  .inbox-pane { max-height: none; }
}
@media (max-width: 900px) {
  .topbar { flex-wrap: wrap; height: auto; padding: 12px 16px; gap: 8px; }
  .nav { flex-wrap: wrap; }
  .grid.two-up, .grid.cards { grid-template-columns: 1fr; }
  .inbox-layout { grid-template-columns: 1fr; }
  .workspace-hero { grid-template-columns: 1fr; }
  .workspace-stats { flex-direction: column; }
  .shell { padding: 0 12px 32px; }
  .reader-meta { flex-direction: column; }
  .detail-meta { flex-direction: column; }
}