/* Letter selection for simple/hard tests; study groups keep their layout. */
.irregular-exercise-page .irv-letters { max-width:920px; display:block; padding-block:24px; }
.irregular-exercise-page .irv-letters .irv-screen-heading h2 { margin:0 0 12px; font-size:clamp(1.5rem,3vw,2rem); line-height:1.2; color:var(--irv-ink); }
.irregular-exercise-page .irv-letters .irv-screen-heading > p:not(.eyebrow) { max-width:660px; margin:0 auto 20px; color:var(--irv-muted); font-size:1rem; line-height:1.6; }
.irregular-exercise-page .irv-letter-tools { display:flex; flex-wrap:wrap; justify-content:flex-end; gap:8px; margin-bottom:12px; }
.irregular-exercise-page :is(.irv-letter-tools,.irv-range-bar) button { min-height:44px; padding:8px 12px; border:1px solid var(--irv-line); border-radius:8px; background:var(--irv-surface); color:var(--irv-ink); font:700 .85rem/1.4 Arial,Helvetica,sans-serif; cursor:pointer; }
.irregular-exercise-page :is(.irv-letter-tools,.irv-range-bar) button:hover { background:var(--irv-field); }
.irregular-exercise-page .irv-letter-grid { display:grid; grid-template-columns:repeat(8,minmax(0,1fr)); gap:10px; margin:0 0 20px; }
html[data-theme] .irregular-exercise-page .irv-letter-button { position:relative; display:grid; place-content:center; gap:4px; min-height:82px; padding:12px 6px; border:2px solid var(--irv-line); border-radius:8px; background:var(--irv-surface); color:var(--irv-ink); font-family:Arial,Helvetica,sans-serif; cursor:pointer; }
.irregular-exercise-page .irv-letter-button strong { font-size:1.5rem; line-height:1.2; }
.irregular-exercise-page .irv-letter-button span { font-size:.85rem; line-height:1.3; color:var(--irv-muted); }
html[data-theme] .irregular-exercise-page .irv-letter-button:hover { border-color:var(--irv-teal); background:var(--irv-field); }
html[data-theme] .irregular-exercise-page .irv-letter-button[aria-pressed=true] { border-color:var(--irv-teal); background:var(--irv-teal-soft); color:var(--irv-teal); }
.irregular-exercise-page .irv-letter-button[aria-pressed=true]::after { content:'✓'; position:absolute; right:5px; top:3px; font-size:.85rem; font-weight:800; }
.irregular-exercise-page .irv-letter-actions { display:grid; grid-template-columns:1fr 1fr; gap:12px; margin:0; padding:16px; border:1px solid var(--irv-line); border-radius:8px; background:var(--irv-surface); }
.irregular-exercise-page .irv-letter-actions p { grid-column:1/-1; margin:0; font-size:.95rem; line-height:1.5; color:var(--irv-muted); }
.irregular-exercise-page .irv-letter-actions .button { width:100%; min-width:0; min-height:48px; padding:12px; border:1px solid transparent; border-radius:8px; font:700 1rem/1.4 Arial,Helvetica,sans-serif; white-space:normal; cursor:pointer; }
html[data-theme] body.irregular-exercise-page .irv-letter-actions .button--primary { color:var(--irv-button-ink); background:var(--irv-coral-fill); border-color:var(--irv-coral-fill); }
html[data-theme] body.irregular-exercise-page .irv-letter-actions .button--primary:is(:hover,:focus-visible) { color:var(--irv-button-ink); background:var(--irv-primary-hover); border-color:var(--irv-primary-hover); }
html[data-theme] body.irregular-exercise-page .irv-letter-actions .button--primary:disabled { color:var(--irv-muted); background:var(--irv-disabled); border-color:var(--irv-line); cursor:default; }
html[data-theme] body.irregular-exercise-page .irv-letter-actions .button--secondary { background:var(--irv-secondary); color:var(--irv-ink); border:1px solid var(--irv-line); }
html[data-theme] body.irregular-exercise-page .irv-letter-actions .button--secondary:is(:hover,:focus-visible) { background:var(--irv-secondary-hover); color:var(--irv-ink); }
.irregular-exercise-page .irv-range-bar { display:flex; flex-shrink:0; justify-content:space-between; align-items:center; gap:8px; color:var(--irv-muted); font-size:.85rem; line-height:1.4; }
.irregular-exercise-page .irv-range-bar > span { min-width:0; overflow-wrap:anywhere; }
.irregular-exercise-page .irv-range-bar button { flex-shrink:0; }
.irregular-exercise-page .irv-groups { justify-content:flex-start; }
.irregular-exercise-page .irv-groups .irv-group-grid { margin:12px 0 20px; }
.irregular-exercise-page .irv-groups .irv-letter-actions { grid-template-columns:1fr; }
html[data-theme] .irregular-exercise-page .irv-group-button { position:relative; }
html[data-theme] .irregular-exercise-page .irv-group-button[aria-pressed=true] { border:2px solid var(--irv-teal); background:var(--irv-teal-soft); }
.irregular-exercise-page .irv-group-button[aria-pressed=true] strong { color:var(--irv-teal); }
.irregular-exercise-page .irv-group-button[aria-pressed=true]::after { content:'✓'; position:absolute; right:7px; top:5px; color:var(--irv-teal); font-weight:800; }
@media(max-width:620px) {
  .irregular-exercise-page .irv-letters { padding-block:14px; }
  .irregular-exercise-page .irv-letter-grid { grid-template-columns:repeat(4,minmax(0,1fr)); gap:8px; }
  html[data-theme] .irregular-exercise-page .irv-letter-button { min-height:68px; padding:8px 4px; }
  .irregular-exercise-page .irv-letter-actions { grid-template-columns:minmax(0,1fr); padding:12px; gap:10px; }
  .irregular-exercise-page .irv-letter-tools { justify-content:space-between; }
}