:root {
  --bg: #f4f6f9;
  --card-bg: #ffffff;
  --ink: #1b2430;
  --ink-soft: #5b6673;
  --border: #e2e6ec;
  --accent: #2657d9;
  --accent-ink: #ffffff;
  --rf: #2e9e6d;
  --lstm: #6d4fd6;
  --hybrid: #d9762e;
  --actual: #1b2430;
  --danger: #cc4b4b;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20, 30, 50, 0.06), 0 8px 24px rgba(20, 30, 50, 0.05);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
}

/* ---------- top bar / nav ---------- */
.topbar {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
  padding: 14px 24px 0;
}
.brand { display: flex; flex-direction: column; gap: 2px; margin-bottom: 12px; }
.brand-mark { font-size: 1.5rem; font-weight: 800; letter-spacing: 0.5px; color: var(--accent); }
.brand-sub { font-size: 0.85rem; color: var(--ink-soft); }

.tabs { display: flex; gap: 4px; overflow-x: auto; }
.tab-btn {
  background: none;
  border: none;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--ink-soft);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  white-space: nowrap;
}
.tab-btn:hover { color: var(--ink); }
.tab-btn.active { color: var(--accent); border-bottom-color: var(--accent); }

main { max-width: 1180px; margin: 0 auto; padding: 28px 24px 60px; }

.tab-panel { display: none; }
.tab-panel.active { display: block; animation: fade 0.25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }

.panel-intro h1 { font-size: 1.5rem; margin: 0 0 8px; display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.panel-intro p { color: var(--ink-soft); max-width: 780px; margin: 0 0 20px; }
.badge {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  background: #eef1f6;
  color: var(--ink-soft);
  padding: 4px 10px;
  border-radius: 999px;
}
@media (prefers-color-scheme: dark) { .badge { background: #232d38; } }

.preview-table { border-collapse: collapse; font-size: 0.82rem; min-width: 500px; }
.preview-table th, .preview-table td { border: 1px solid var(--border); padding: 6px 10px; text-align: left; white-space: nowrap; }
.preview-table th { background: #eef1f6; position: sticky; top: 0; z-index: 1; }
@media (prefers-color-scheme: dark) { .preview-table th { background: #232d38; } }

input[type="file"] { font: inherit; }

/* ---------- cards ---------- */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px 22px;
  margin-bottom: 20px;
}
.card h3 { margin: 0 0 4px; font-size: 1.05rem; }
.card-sub { color: var(--ink-soft); font-size: 0.85rem; margin: 0 0 14px; }

.card-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.card-grid.three { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 860px) {
  .card-grid, .card-grid.three { grid-template-columns: 1fr; }
}

.chart-wrap { position: relative; height: 260px; }
.chart-wrap.tall { height: 360px; }

/* ---------- stat tiles ---------- */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 14px;
  margin-bottom: 20px;
}
.stat-tile {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  box-shadow: var(--shadow);
}
.stat-tile .stat-value { font-size: 1.4rem; font-weight: 700; color: var(--accent); }
.stat-tile .stat-label { font-size: 0.78rem; color: var(--ink-soft); text-transform: uppercase; letter-spacing: 0.04em; }

/* ---------- forecast controls ---------- */
.controls-card .control-row {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: end;
}
.control-row label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--ink-soft);
}
.control-row input, .control-row select {
  font: inherit;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fbfcfe;
}
.btn-primary, .btn-secondary {
  font: inherit;
  font-weight: 700;
  border-radius: 8px;
  padding: 10px 18px;
  border: none;
  cursor: pointer;
}
.btn-primary { background: var(--accent); color: var(--accent-ink); }
.btn-primary:hover { background: #1e46b8; }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-secondary { background: #eef1f6; color: var(--ink); }
.btn-secondary:hover { background: #e2e6ec; }

.status-line { margin: 12px 0 0; font-size: 0.85rem; color: var(--ink-soft); min-height: 1.2em; }
.status-line.error { color: var(--danger); font-weight: 600; }

.legend-row { display: flex; gap: 18px; flex-wrap: wrap; margin-bottom: 8px; font-size: 0.82rem; color: var(--ink-soft); }
.legend-row span.dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; vertical-align: middle; }

/* ---------- metric cards ---------- */
.metric-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px 18px;
}
.metric-card .metric-label { font-weight: 700; font-size: 0.9rem; }
.metric-card[data-model="rf"] .metric-label { color: var(--rf); }
.metric-card[data-model="lstm"] .metric-label { color: var(--lstm); }
.metric-card[data-model="hybrid"] .metric-label { color: var(--hybrid); }
.metric-body { margin-top: 8px; display: flex; gap: 16px; flex-wrap: wrap; }
.metric-body .m { display: flex; flex-direction: column; }
.metric-body .m .v { font-size: 1.25rem; font-weight: 700; }
.metric-body .m .k { font-size: 0.72rem; color: var(--ink-soft); text-transform: uppercase; }
.metric-card.best { outline: 2px solid #2e9e6d; }

.kv-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 8px 20px; }
.kv-list div { display: flex; justify-content: space-between; border-bottom: 1px dashed var(--border); padding: 6px 0; font-size: 0.88rem; }
.kv-list div b { color: var(--ink-soft); font-weight: 600; }

.about-card h3 { margin-top: 22px; }
.about-card h3:first-child { margin-top: 0; }
.about-card ul { padding-left: 22px; color: var(--ink-soft); }
.about-card p { color: var(--ink-soft); }
.about-card code { background: #eef1f6; padding: 1px 6px; border-radius: 4px; font-size: 0.85em; }

.footer { text-align: center; padding: 24px; color: var(--ink-soft); font-size: 0.8rem; }

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #10151d;
    --card-bg: #182029;
    --ink: #e8ecf2;
    --ink-soft: #92a0b3;
    --border: #262f3b;
    --shadow: 0 1px 2px rgba(0,0,0,0.3), 0 8px 24px rgba(0,0,0,0.25);
  }
  .control-row input, .control-row select { background: #101720; color: var(--ink); }
  .btn-secondary { background: #232d38; color: var(--ink); }
  .btn-secondary:hover { background: #2b3644; }
  .about-card code { background: #232d38; }
}