/* ── Design tokens ─────────────────────────────────────────────────────────── */
:root {
  /* Surfaces */
  --bg:             #fafaf9;
  --bg-elevated:    #ffffff;
  --bg-subtle:      #f4f4f5;

  /* Text */
  --text:           #111827;
  --text-secondary: #6b7280;
  --text-tertiary:  #9ca3af;

  /* Accent (single) */
  --accent:         #1d4ed8;
  --accent-hover:   #1e40af;
  --accent-subtle:  #eff6ff;

  /* Semantic — muted */
  --green:          #15803d;
  --green-bg:       #f0fdf4;
  --green-text:     #166534;

  --amber:          #b45309;
  --amber-bg:       #fffbeb;
  --amber-text:     #92400e;

  --red:            #b91c1c;
  --red-bg:         #fef2f2;
  --red-text:       #991b1b;

  /* Chart */
  --chart-bar:      rgba(99, 132, 204, 0.55);
  --chart-bar-h:    rgba(99, 132, 204, 0.85);
  --chart-seed:     rgba(124, 58, 237, 0.65);
  --chart-seed-h:   rgba(124, 58, 237, 0.9);

  /* Structure */
  --border:         #e5e7eb;
  --border-focus:   #93c5fd;
  --radius-sm:      4px;
  --radius:         8px;
  --radius-lg:      12px;
  --shadow:         0 1px 3px rgba(0,0,0,0.06), 0 0 0 1px rgba(0,0,0,0.04);

  /* Fonts */
  --font:           'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:      'JetBrains Mono', 'Fira Code', ui-monospace, monospace;

  /* Motion */
  --ease:           150ms ease;
}

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

html { font-size: 16px; }

body {
  font-family: var(--font);
  font-size: 0.9375rem;
  line-height: 1.6;
  letter-spacing: 0.01em;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

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

/* ── Header ────────────────────────────────────────────────────────────────── */
header {
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
  padding: 2.5rem 1.5rem 2rem;
}

.header-inner {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
}

.wordmark {
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  color: var(--text);
  line-height: 1;
  margin-bottom: 0.5rem;
}

.wordmark-accent {
  color: var(--accent);
}

.tagline {
  font-size: 0.9rem;
  color: var(--text-secondary);
  letter-spacing: 0.01em;
}

/* ── Main ──────────────────────────────────────────────────────────────────── */
main {
  flex: 1;
  max-width: 860px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* ── Panel (unified card) ──────────────────────────────────────────────────── */
.panel {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 1.75rem 2rem;
}

.panel-header {
  margin-bottom: 1.25rem;
}

.panel-title {
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 0.2rem;
}

.panel-subtitle {
  font-size: 0.82rem;
  color: var(--text-tertiary);
  line-height: 1.5;
}

/* ── Input panel ───────────────────────────────────────────────────────────── */
.input-panel {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* Field groups */
.field-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding-bottom: 1.25rem;
}

.field-group--secondary {
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
  padding-bottom: 0;
}

.field-label {
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--text-secondary);
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.field-meta {
  font-weight: 400;
  color: var(--text-tertiary);
  font-size: 0.78rem;
  letter-spacing: 0.01em;
}

/* Inputs */
.seq-field {
  width: 100%;
  padding: 0.6rem 0.875rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--text);
  outline: none;
  transition: border-color var(--ease), box-shadow var(--ease);
}
.seq-field::placeholder {
  color: var(--text-tertiary);
  font-weight: 400;
}
.seq-field:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(147, 197, 253, 0.4);
}
.seq-field.input-error {
  border-color: #fca5a5;
  box-shadow: 0 0 0 3px rgba(252, 165, 165, 0.3);
}
.seq-field--secondary {
  background: var(--bg);
  font-size: 0.875rem;
}

/* Input row (gRNA + buttons) */
.input-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.input-row .seq-field {
  flex: 1;
  min-width: 200px;
}

/* Optional badge */
.badge-optional {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.1rem 0.4rem;
  border-radius: 99px;
  background: var(--bg-subtle);
  color: var(--text-tertiary);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  vertical-align: baseline;
}

/* ── Buttons ───────────────────────────────────────────────────────────────── */
.btn-primary, .btn-ghost {
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  cursor: pointer;
  border: none;
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  white-space: nowrap;
  transition: background var(--ease), color var(--ease), border-color var(--ease);
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; }

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
}
.btn-ghost:hover { background: var(--bg-subtle); color: var(--text); }

/* Spinner */
.spinner {
  width: 14px;
  height: 14px;
  border: 1.5px solid rgba(255,255,255,0.35);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.65s linear infinite;
  flex-shrink: 0;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* Error */
.field-error {
  font-size: 0.82rem;
  color: var(--red-text);
  padding: 0.55rem 0.875rem;
  background: var(--red-bg);
  border: 1px solid #fecaca;
  border-radius: var(--radius);
  margin-top: 0.5rem;
}

/* ── Score grid ────────────────────────────────────────────────────────────── */
.score-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

@media (max-width: 560px) {
  .score-grid { grid-template-columns: 1fr; }
}

/* ── Score card ────────────────────────────────────────────────────────────── */
.score-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.score-card-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.card-icon {
  width: 16px;
  height: 16px;
  color: var(--text-tertiary);
  flex-shrink: 0;
}

.score-card-title {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-secondary);
}

/* Large monospace readout */
.score-readout {
  font-family: var(--font-mono);
  font-size: 3rem;
  font-weight: 600;
  letter-spacing: -0.04em;
  line-height: 1;
  color: var(--text);
}

/* Thin progress bar */
.score-track {
  width: 100%;
  height: 4px;
  background: var(--bg-subtle);
  border-radius: 99px;
  overflow: hidden;
}
.score-fill {
  height: 100%;
  border-radius: 99px;
  transition: width 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}
.score-fill--eff  { background: #22c55e; }
.score-fill--risk { background: #f87171; }

/* Verbal label badge */
.score-badge {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.2rem 0.6rem;
  border-radius: 99px;
  align-self: flex-start;
  line-height: 1.6;
}
.badge--green { background: var(--green-bg);  color: var(--green-text); }
.badge--amber { background: var(--amber-bg);  color: var(--amber-text); }
.badge--red   { background: var(--red-bg);    color: var(--red-text);   }

/* Method footnote (replaces limitation note box) */
.method-footnote {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  line-height: 1.55;
  border-top: 1px solid var(--border);
  padding-top: 0.65rem;
  margin-top: auto;
  font-style: italic;
}

/* ── Candidates panel ──────────────────────────────────────────────────────── */
.table-scroll { overflow-x: auto; }

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.845rem;
}

.data-table thead tr {
  border-bottom: 1px solid var(--border);
}

.data-table th {
  padding: 0.5rem 0.875rem;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  text-align: left;
  white-space: nowrap;
}

.data-table td {
  padding: 0.55rem 0.875rem;
  border-bottom: 1px solid var(--bg-subtle);
  vertical-align: middle;
}

.data-table tbody tr:last-child td { border-bottom: none; }
.data-table tbody tr:hover { background: var(--bg); }

.col-center { text-align: center !important; }

/* DNA sequence cell */
.seq-cell {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--text);
}

/* Mismatch nucleotide highlight */
.mm-nt {
  color: var(--red);
  font-weight: 700;
}

/* Raw score in table */
.raw-score {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-secondary);
}

/* Relative rank badges */
.rank-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  white-space: nowrap;
}
.rank-1 { background: var(--red-bg);   color: var(--red-text);   }
.rank-2 { background: #fff7ed;         color: #9a3412;           }
.rank-3 { background: var(--amber-bg); color: var(--amber-text); }
.rank-4 { background: var(--bg-subtle);color: var(--text-secondary); }

/* ── Saliency panel ────────────────────────────────────────────────────────── */
.saliency-panel { }

.seed-legend-label {
  display: inline-block;
  font-weight: 600;
  color: #7c3aed;
}

.chart-wrap {
  position: relative;
  height: 210px;
}

.seq-display {
  margin-top: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  text-align: center;
  word-break: break-all;
}

/* ── Footer ────────────────────────────────────────────────────────────────── */
footer {
  text-align: center;
  padding: 1.25rem 1rem;
  font-size: 0.8rem;
  color: var(--text-tertiary);
  border-top: 1px solid var(--border);
  background: var(--bg-elevated);
}

/* ── Utility ───────────────────────────────────────────────────────────────── */
.hidden { display: none !important; }