/* ============================================
   LESSON 4 — SPECIFIC STYLES
   Recognising Numbers
   ============================================ */

/* ── Choice Grid ── */
.l4-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 8px;
}
.l4-row {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 10px 16px;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color .2s;
}
.l4-row:hover { border-color: rgba(201,168,76,0.3); }
.l4-row-label {
  font-size: 1rem;
  font-weight: 700;
  color: var(--gold);
  min-width: 20px;
  padding-top: 9px;
}
.l4-row-content {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1;
}
.l4-opts {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

/* Inline explanation row — hidden until checked */
.l4-exp {
  display: none;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 6px;
  font-size: 1rem;
  border-radius: 6px;
  padding: 5px 10px;
}
.l4-exp-show { display: flex; }
.l4-exp-ok  { background: rgba(74,222,128,0.08);  border: 1px solid rgba(74,222,128,0.2);  }
.l4-exp-err { background: rgba(248,113,113,0.08); border: 1px solid rgba(248,113,113,0.2); }

.l4-exp-check       { color: var(--success); font-weight: 700; }
.l4-exp-cross       { color: var(--error);   font-weight: 700; }
.l4-exp-correct-ans { color: var(--gold);    font-weight: 600; white-space: nowrap; }
.l4-exp-divider     { color: var(--text-muted); }
.l4-exp-note        { color: var(--text-muted); }

/* ── Option Buttons ── */
.l4-opt {
  padding: 8px 20px;
  border-radius: var(--radius);
  border: 2px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: all .18s;
  letter-spacing: .02em;
}
.l4-opt:hover:not(:disabled)  { border-color: var(--gold); color: var(--text); }
.l4-opt-sel     { background: rgba(201,168,76,0.12); border-color: var(--gold); color: var(--gold); }
.l4-opt-correct { background: rgba(122,182,72,0.12); border-color: var(--success); color: var(--success); cursor: default; }
.l4-opt-wrong   { background: rgba(192,57,43,0.1);  border-color: var(--error);   color: var(--error); }
.l4-opt:disabled { cursor: default; }

/* ── Shake ── */
.l4-shake {
  animation: l4shake .45s ease;
}
@keyframes l4shake {
  0%,100%{transform:translateX(0)}
  20%{transform:translateX(-6px)}
  40%{transform:translateX(6px)}
  60%{transform:translateX(-4px)}
  80%{transform:translateX(4px)}
}

/* ── Explanation ── */
.l4-exp-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.l4-exp-row {
  display: grid;
  grid-template-columns: 24px 130px 1fr;
  align-items: start;
  gap: 14px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
  font-size: 1rem;
}
.l4-exp-row:last-child { border-bottom: none; }
.l4-exp-row:nth-child(odd) { background: var(--bg-card-2); }
.l4-exp-id {
  font-weight: 800;
  color: var(--gold);
  font-size: 1rem;
}
.l4-exp-pair {
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}
.l4-exp-note {
  color: var(--text-muted);
  line-height: 1.55;
}
@media (max-width:600px) {
  .l4-exp-row { grid-template-columns: 24px 1fr; }
  .l4-exp-pair { grid-column: 2; }
  .l4-exp-note { grid-column: 1 / -1; padding-left: 0; }
}

/* ── Study Tip ── */
.l4-tip-main {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 18px 22px;
  margin-bottom: 20px;
  font-size: 1rem;
  color: var(--text-muted);
  line-height: 1.7;
}
.l4-tip-icon { font-size: 1.5rem; flex-shrink: 0; }

.l4-tip-grid {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}
.l4-tip-card {
  flex: 1;
  min-width: 180px;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 18px 20px;
}
.l4-tc-title {
  font-weight: 800;
  color: var(--gold);
  font-size: 1rem;
  margin-bottom: 6px;
}
.l4-tc-stress {
  font-size: 1rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 10px;
}
.l4-tc-stress span { color: var(--gold); font-weight: 700; }
.l4-tc-examples {
  font-size: 1rem;
  color: var(--text-muted);
  line-height: 1.8;
}
.l4-tc-vs {
  font-size: 1.6rem;
  color: var(--error);
  font-weight: 900;
  flex-shrink: 0;
}

.l4-tip-rules {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.l4-tip-rule-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 1rem;
  color: var(--text-muted);
  line-height: 1.6;
}
.l4-rule-icon { font-size: 1.25rem; flex-shrink: 0; }