/* ─── Design tokens ─────────────────────────────────────── */
:root {
  --bg:          #0d0f14;
  --bg-card:     #141720;
  --bg-card-2:   #1a1e2b;
  --border:      #252a3a;
  --border-lite: #2e3347;

  --text:        #e8eaf0;
  --text-muted:  #7a8099;
  --text-faint:  #4a5068;

  --accent:      #4f8ef7;
  --accent-dim:  #1e3a6e;
  --green:       #34c784;
  --green-dim:   #0f3320;
  --amber:       #f0a030;
  --amber-dim:   #3a2800;
  --red:         #e05555;

  --radius:      10px;
  --radius-sm:   6px;
  --shadow:      0 4px 24px rgba(0,0,0,0.4);
  --font:        'Inter', system-ui, sans-serif;
  --mono:        'JetBrains Mono', monospace;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

.hidden { display: none !important; }

/* ─── Header ────────────────────────────────────────────── */
.header {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
  position: sticky;
  top: 0;
  background: rgba(13,15,20,0.92);
  backdrop-filter: blur(12px);
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand { display: flex; align-items: center; gap: 12px; }

.brand-icon {
  font-size: 24px;
  width: 40px; height: 40px;
  background: var(--accent-dim);
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
}

.brand-title { font-size: 15px; font-weight: 600; letter-spacing: -0.01em; }
.brand-subtitle { font-size: 11px; color: var(--text-muted); letter-spacing: 0.02em; text-transform: uppercase; }

.nav { display: flex; gap: 24px; }
.nav-link { font-size: 14px; color: var(--text-muted); font-weight: 500; }
.nav-link:hover { color: var(--text); text-decoration: none; }

/* ─── Hero ──────────────────────────────────────────────── */
.hero {
  padding: 72px 0 56px;
  text-align: center;
}

.hero-title {
  font-size: clamp(28px, 5vw, 44px);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #e8eaf0 0%, #7a8099 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 16px;
  color: var(--text-muted);
  max-width: 620px;
  margin: 0 auto 28px;
  line-height: 1.7;
}

.hero-badges { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }

.badge {
  font-size: 12px;
  font-weight: 500;
  padding: 4px 12px;
  border-radius: 20px;
  border: 1px solid var(--border-lite);
  color: var(--text-muted);
  background: var(--bg-card);
  font-family: var(--mono);
}

/* ─── Main grid ─────────────────────────────────────────── */
.main { padding: 0 0 80px; }

.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}

@media (max-width: 768px) { .grid { grid-template-columns: 1fr; } }

/* ─── Cards ─────────────────────────────────────────────── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.card-header { margin-bottom: 24px; }
.card-title { font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.card-desc { font-size: 12px; color: var(--text-muted); font-family: var(--mono); line-height: 1.5; }

/* ─── Upload zone ───────────────────────────────────────── */
.upload-zone {
  border: 2px dashed var(--border-lite);
  border-radius: var(--radius);
  padding: 40px 24px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  margin-bottom: 16px;
}

.upload-zone:hover, .upload-zone.drag-over {
  border-color: var(--accent);
  background: var(--accent-dim);
}

.upload-icon { font-size: 28px; margin-bottom: 10px; }
.upload-text { font-size: 15px; font-weight: 500; margin-bottom: 4px; }
.upload-hint { font-size: 13px; color: var(--text-muted); }

.file-info {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 14px;
  background: var(--bg-card-2);
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  font-size: 13px;
}

.file-name { font-family: var(--mono); color: var(--green); }
.file-rows { color: var(--text-muted); }

/* ─── Buttons ───────────────────────────────────────────── */
.btn {
  width: 100%;
  padding: 13px 24px;
  border-radius: var(--radius-sm);
  border: none;
  font-family: var(--font);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s;
}

.btn:active { transform: scale(0.98); }

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover:not(:disabled) { opacity: 0.88; }
.btn-primary:disabled { opacity: 0.3; cursor: not-allowed; }

.sample-link {
  text-align: center;
  margin-top: 14px;
  font-size: 13px;
  color: var(--text-muted);
}

/* ─── Results: empty state ──────────────────────────────── */
.empty-state, .loading-state {
  text-align: center;
  padding: 60px 24px;
}

.empty-icon { font-size: 36px; margin-bottom: 12px; opacity: 0.4; }
.empty-text { font-size: 15px; font-weight: 500; color: var(--text-muted); margin-bottom: 4px; }
.empty-hint { font-size: 13px; color: var(--text-faint); }

/* ─── Spinner ───────────────────────────────────────────── */
.spinner {
  width: 36px; height: 36px;
  border: 3px solid var(--border-lite);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 16px;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text { font-size: 14px; color: var(--text-muted); }

/* ─── RUL display ───────────────────────────────────────── */
.rul-display {
  text-align: center;
  padding: 28px 0 16px;
}

.rul-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.rul-value {
  font-size: 72px;
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.rul-value.critical { color: var(--red); }
.rul-value.caution  { color: var(--amber); }
.rul-value.healthy  { color: var(--green); }

.rul-unit {
  font-size: 16px;
  color: var(--text-muted);
  margin-top: 6px;
}

.rul-band {
  font-size: 13px;
  color: var(--text-faint);
  margin-top: 6px;
  font-family: var(--mono);
}

/* ─── Gauge bar ─────────────────────────────────────────── */
.rul-gauge-wrap { padding: 16px 0 24px; }

.rul-gauge {
  position: relative;
  height: 8px;
  background: var(--bg-card-2);
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: 6px;
}

.gauge-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.8s cubic-bezier(0.25, 1, 0.5, 1);
  background: linear-gradient(90deg, var(--red) 0%, var(--amber) 40%, var(--green) 100%);
}

.gauge-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-faint);
  font-family: var(--mono);
}

/* ─── SHAP bars ─────────────────────────────────────────── */
.shap-section {
  border-top: 1px solid var(--border);
  padding-top: 20px;
}

.shap-title { font-size: 14px; font-weight: 600; margin-bottom: 4px; }
.shap-subtitle { font-size: 12px; color: var(--text-muted); margin-bottom: 16px; }

.shap-row { margin-bottom: 12px; }

.shap-row-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 5px;
}

.shap-feat { font-size: 12px; font-family: var(--mono); color: var(--text); }
.shap-val  { font-size: 12px; font-family: var(--mono); }
.shap-val.positive { color: var(--green); }
.shap-val.negative { color: var(--red); }

.shap-bar-track {
  height: 6px;
  background: var(--bg-card-2);
  border-radius: 3px;
  overflow: hidden;
}

.shap-bar-fill {
  height: 100%;
  border-radius: 3px;
  transition: width 0.6s ease;
}

.shap-bar-fill.positive { background: var(--green); }
.shap-bar-fill.negative { background: var(--red); }

.shap-dir {
  font-size: 10px;
  color: var(--text-faint);
  margin-top: 3px;
}

/* ─── Warning box ───────────────────────────────────────── */
.warning-box {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: var(--amber-dim);
  border: 1px solid var(--amber);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  margin-top: 20px;
  font-size: 13px;
  color: var(--amber);
}

.warning-icon { flex-shrink: 0; }

/* ─── Methodology ───────────────────────────────────────── */
.methodology {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 72px 0;
}

.section-title {
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 40px;
  text-align: center;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

@media (max-width: 900px) { .method-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 500px) { .method-grid { grid-template-columns: 1fr; } }

.method-step {
  padding: 24px;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.step-num {
  font-size: 11px;
  font-family: var(--mono);
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: 0.06em;
}

.step-title { font-size: 15px; font-weight: 600; margin-bottom: 8px; }
.step-desc  { font-size: 13px; color: var(--text-muted); line-height: 1.6; }

/* ─── Footer ────────────────────────────────────────────── */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-left { font-size: 13px; color: var(--text-muted); }
.footer-left strong { color: var(--text); }

.footer-right { display: flex; gap: 20px; }
.footer-right a { font-size: 13px; color: var(--text-muted); }
.footer-right a:hover { color: var(--text); text-decoration: none; }