main {
  display: grid;
  grid-template-columns: 1fr 1fr;
  column-gap: 1rem;
  row-gap: 0;
  align-items: start;
  margin-bottom: 0;
}

.panel-setup  { grid-column: 1; grid-row: 1; }
.panel-method { grid-column: 2; grid-row: 1; }

#dif-results-section {
  max-width: 1400px;
  margin: 1.5rem auto;
  padding: 0 1.25rem;
}
#dif-results-section .panel { margin-bottom: 1rem; }
#dif-results-section .panel:last-child { margin-bottom: 0; }

/* ── Drop zone — base styles from shared drop-zone.css ────────── */
.shared-drop-zone .drop-zone-icon { font-size: 1.8rem; margin-bottom: .3rem; }

/* ── Status line ──────────────────────────────────────────────── */
.dif-status {
  font-size: var(--txt-sm);
  margin-top: .5rem;
  min-height: 1.1em;
  transition: color .2s;
}
.dif-status--ok    { color: var(--clr-status-success, #3fb950); }
.dif-status--error { color: var(--clr-danger, #f85149); }
.dif-status--idle  { color: var(--clr-muted); }

/* ── Form rows ────────────────────────────────────────────────── */
.panel-block { padding: .65rem .9rem; border-bottom: 1px solid var(--clr-border); }
.panel-block:last-child { border-bottom: none; }

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: .55rem;
  margin-top: .5rem;
}
.form-row.single { grid-template-columns: 1fr; }

.form-field { display: flex; flex-direction: column; gap: .22rem; }
.form-field label {
  font-size: var(--txt-xs);
  font-weight: var(--txt-w-semibold, 600);
  color: var(--clr-muted);
  text-transform: uppercase;
  letter-spacing: .04em;
}
.form-field .hint {
  font-size: var(--txt-xs);
  color: var(--clr-muted);
  margin: 0;
}

select, input[type='number'], input[type='text'] {
  width: 100%;
  padding: .35rem .5rem;
  font-size: var(--txt-sm);
  border-radius: 6px;
  border: 1px solid var(--clr-border);
  background: var(--clr-surface, var(--clr-surface));
  color: var(--clr-text);
}

input[type='number']::-webkit-outer-spin-button,
input[type='number']::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
input[type='number'] { appearance: textfield; -moz-appearance: textfield; }

.section-label {
  font-size: var(--txt-sm-plus);
  font-weight: var(--txt-w-bold, 700);
  text-transform: uppercase;
  letter-spacing: .04em;
  color: var(--clr-primary);
  margin-bottom: .4rem;
  display: block;
}

/* ── Method radio buttons ─────────────────────────────────────── */
.method-options { display: grid; grid-template-columns: repeat(3, 1fr); gap: .35rem; margin-top: .3rem; }
.method-options label {
  display: flex; align-items: center; justify-content: center; gap: .3rem; text-align: center;
  font-size: var(--txt-sm); cursor: pointer;
  padding: .28rem .55rem;
  border: 1px solid var(--clr-border);
  border-radius: 6px;
  transition: border-color .15s, background .15s;
}
.method-options input[type='radio'] { display: none; }
.method-options input[type='radio']:checked + span {
  font-weight: var(--txt-w-bold, 700);
  color: var(--clr-primary);
}
.method-options label:has(input:checked) {
  border-color: var(--clr-primary);
  background: color-mix(in oklab, var(--clr-primary) 8%, var(--clr-surface));
}

/* ── Stepper — shared form-controls.css provides the base styles ─ */

/* ── Sample data buttons ──────────────────────────────────────── */
.sample-btns { display: flex; flex-wrap: wrap; gap: .35rem; margin-top: .4rem; }

/* ── Progress — base styles from shared progress-bar.css ─────── */

/* ── Warnings ─────────────────────────────────────────────────── */
.dif-warnings { display: flex; flex-direction: column; gap: .4rem; padding: .5rem .9rem; }
.dif-warning {
  display: flex; gap: .45rem; align-items: flex-start;
  font-size: var(--txt-sm);
  color: color-mix(in oklab, var(--clr-status-warning, #d29922) 80%, var(--clr-text));
  background: color-mix(in oklab, var(--clr-status-warning, #d29922) 10%, var(--clr-surface));
  border: 1px solid color-mix(in oklab, var(--clr-status-warning, #d29922) 30%, var(--clr-border));
  border-radius: 7px;
  padding: .45rem .65rem;
}
.warn-icon { flex-shrink: 0; }

/* ── Results ──────────────────────────────────────────────────── */
.dif-results-body { padding: .65rem .9rem .9rem; }

#dif-mh-results,
#dif-tsw-results {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  align-items: flex-start;
  justify-content: center;
}

.dif-dim-section {
  flex: 0 1 auto;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: .4rem;
}

.dif-dim-title {
  font-size: var(--txt-sm-plus);
  font-weight: var(--txt-w-bold, 700);
  color: var(--clr-primary);
  margin: 0 0 .5rem;
  display: flex; align-items: center; gap: .5rem;
  flex-wrap: wrap;
}
.dif-iter-note {
  font-size: var(--txt-xs);
  font-weight: 400;
  color: var(--clr-muted);
}

/* ── Tables ───────────────────────────────────────────────────── */
.shared-results-table th[title] { text-decoration: underline dotted var(--clr-muted); }
.row-variant td {
  color: color-mix(in oklab, var(--clr-danger, #f85149) 80%, var(--clr-text));
  background: color-mix(in oklab, var(--clr-danger, #f85149) 5%, var(--clr-surface));
}
.row-variant:hover td {
  background: color-mix(in oklab, var(--clr-danger, #f85149) 9%, var(--clr-surface));
}

.cell-item { font-weight: var(--txt-w-semibold, 600); }
.cell-b { font-size: var(--txt-xs); max-width: 180px; white-space: normal; }
.cell-error { color: var(--clr-muted); font-style: italic; }

/* ── Badges ───────────────────────────────────────────────────── */
.dif-badge {
  font-size: var(--txt-xs);
  font-weight: 700;
  padding: .12rem .4rem;
  border-radius: 4px;
  letter-spacing: .04em;
  text-transform: uppercase;
}
.badge-variant {
  background: color-mix(in oklab, var(--clr-danger, #f85149) 15%, transparent);
  color: var(--clr-danger, #f85149);
  border: 1px solid color-mix(in oklab, var(--clr-danger, #f85149) 35%, transparent);
}
.badge-invariant {
  background: color-mix(in oklab, var(--clr-status-success, #3fb950) 12%, transparent);
  color: var(--clr-status-success, #3fb950);
  border: 1px solid color-mix(in oklab, var(--clr-status-success, #3fb950) 30%, transparent);
}

/* ── Test-level metrics strip ─────────────────────────────────── */
.dif-testlevel {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: .4rem;
  margin-top: .5rem;
}
.tl-metric {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: .15rem;
  padding: .35rem .3rem .4rem;
  background: color-mix(in oklab, var(--clr-surface) 60%, var(--clr-bg));
  border: 1px solid var(--clr-border);
  border-radius: 7px;
}
.tl-label {
  font-size: var(--txt-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .04em;
  color: var(--clr-muted);
}
.tl-val {
  font-weight: 700;
  font-size: var(--txt-sm-plus);
  color: var(--clr-text);
}

/* ── Nested multi-level combobox ──────────────────────────────── */
#dif-multilevel-results {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

.dif-nested-nav {
  display: flex;
  align-items: center;
  gap: .65rem;
  padding: .5rem .8rem;
  background: color-mix(in oklab, var(--clr-primary) 8%, var(--clr-surface));
  border: 1px solid color-mix(in oklab, var(--clr-primary) 22%, var(--clr-border));
  border-radius: 8px;
  margin-bottom: .75rem;
}
.dif-nested-nav-label {
  font-size: var(--txt-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .04em;
  color: var(--clr-primary);
  white-space: nowrap;
  flex-shrink: 0;
  cursor: default;
}
.dif-nested-pick {
  width: auto;
  min-width: 160px;
  max-width: 320px;
  flex-shrink: 0;
}
.dif-nested-counter {
  margin-left: auto;
  font-size: var(--txt-xs);
  color: var(--clr-muted);
  white-space: nowrap;
  flex-shrink: 0;
}
.dif-nested-panel { display: flex; flex-direction: column; gap: 1rem; }
.dif-results-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  align-items: flex-start;
  justify-content: center;
}

/* ── Export button ────────────────────────────────────────────── */
.dif-export-btn { margin-top: .5rem; }

/* ── Large dataset warning ────────────────────────────────────── */
.dif-size-warn {
  font-size: var(--txt-xs);
  color: color-mix(in oklab, var(--clr-status-warning, #d29922) 85%, var(--clr-text));
  margin-top: .3rem;
}

/* ── Run / Cancel row ─────────────────────────────────────────── */
.run-cancel-row { display: flex; gap: .5rem; align-items: stretch; }
.run-cancel-row #dif-run-btn { flex: 1; }
.dif-cancel-btn { flex-shrink: 0; white-space: nowrap; }

/* ── Type detected note ───────────────────────────────────────── */
.type-detected-note {
  font-size: var(--txt-xs);
  color: var(--clr-muted);
  margin-top: .2rem;
}

/* ── Responsive ───────────────────────────────────────────────── */
@media (max-width: 47.5em) {
  main { grid-template-columns: 1fr; }
  .panel-setup, .panel-method { grid-column: auto; grid-row: auto; }
}

@media (max-width: 31.25em) {
  .form-row { grid-template-columns: 1fr; }
  .method-options { gap: .25rem; }
  .shared-results-table { font-size: var(--txt-xs); }
  .shared-results-table th, .shared-results-table td { padding: .25rem .35rem; }
}