:root {
  --int-color: #2563eb;
  --int-light: #dbeafe;
  --int-dark:  #1e40af;
  --str-color: #d97706;
  --str-light: #fef3c7;
  --str-dark:  #92400e;
  --res-color: #10b981;
  --res-light: #d1fae5;
  --res-dark:  #065f46;
  --err-color: #ef4444;
  --err-light: #fef2f2;
  --err-dark:  #991b1b;
}

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 20px 60px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.lead { text-align: center; color: var(--muted-color); font-size: 1rem; margin: -12px 0 0; }

.sec-header { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; }
.sec-header h2 { font-size: 1.15rem; font-weight: 700; margin: 0; color: #1a202c; }

.badge {
  display: inline-block;
  padding: 3px 12px;
  border-radius: 999px;
  font-size: .82rem;
  font-weight: 800;
}
.type-badge { background: var(--int-light);  color: var(--int-dark); }
.plus-badge { background: var(--res-light);  color: var(--res-dark); }
.conv-badge { background: var(--str-light);  color: var(--str-dark); }

/* ===== Controls ===== */
.controls-row { display: flex; align-items: flex-end; gap: 12px; flex-wrap: wrap; margin-bottom: 16px; }
.input-group  { display: flex; flex-direction: column; gap: 4px; }
.input-label {
  font-size: .72rem;
  font-weight: 700;
  color: var(--muted-color);
  text-transform: uppercase;
  letter-spacing: .5px;
}
.demo-input {
  padding: 8px 10px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: .95rem;
  width: 120px;
  background: #fff;
  color: #1a202c;
}
.demo-input:focus { outline: none; border-color: var(--brand); box-shadow: 0 0 0 3px rgba(0,120,215,.12); }
.mono { font-family: 'Courier New', monospace; }

/* ===== Type pills ===== */
.type-pill {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: .78rem;
  font-weight: 800;
  font-family: 'Courier New', monospace;
}
.int-pill { background: var(--int-light); color: var(--int-dark); border: 1.5px solid var(--int-color); }
.str-pill { background: var(--str-light); color: var(--str-dark); border: 1.5px solid var(--str-color); }
.res-pill { background: var(--res-light); color: var(--res-dark); border: 1.5px solid var(--res-color); }

/* ===== Type compare (section 1) ===== */
.compare-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 8px;
}

.compare-panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 18px 14px;
  border-radius: 12px;
  border: 2.5px solid;
  text-align: center;
}
.compare-panel.int-panel         { border-color: var(--int-color); background: var(--int-light); }
.compare-panel.str-panel         { border-color: var(--str-color); background: var(--str-light); }
.compare-panel.int-panel.invalid { border-color: var(--err-color); background: var(--err-light); }

.compare-val {
  font-family: 'Courier New', monospace;
  font-size: 1.4rem;
  font-weight: 800;
  color: #1a202c;
}

.invalid-note {
  font-size: .8rem;
  color: var(--err-dark);
  font-style: italic;
}

.compare-note {
  font-size: .83rem;
  color: var(--muted-color);
  text-align: center;
  margin-top: 4px;
}

/* ===== Counting blocks ===== */
.blocks-row {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  justify-content: center;
  align-items: center;
  min-height: 18px;
}

.count-block {
  display: inline-block;
  width: 13px;
  height: 13px;
  background: var(--int-color);
  border-radius: 3px;
  flex-shrink: 0;
}
.count-block.res-block { background: var(--res-color); }

.block-more {
  font-size: .72rem;
  font-weight: 700;
  color: var(--int-dark);
  margin-left: 2px;
}
.block-zero {
  font-size: .78rem;
  color: var(--muted-color);
  font-style: italic;
}

/* ===== Char tiles ===== */
.char-tiles-row {
  display: flex;
  flex-wrap: wrap;
  gap: 2px;
  justify-content: center;
  align-items: center;
  min-height: 28px;
}

.char-tile {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 5px;
  font-family: 'Courier New', monospace;
  font-size: .82rem;
  font-weight: 700;
  border: 1.5px solid;
  flex-shrink: 0;
}
.char-tile.a-tile { background: var(--int-light); border-color: var(--int-color); color: var(--int-dark); }
.char-tile.b-tile { background: var(--str-light); border-color: var(--str-color); color: var(--str-dark); }

.empty-tile { font-size: .78rem; color: var(--muted-color); font-style: italic; }
.tile-more  { font-size: .72rem; font-weight: 700; color: var(--muted-color); margin-left: 2px; }

/* ===== Plus controls (section 2) ===== */
.plus-controls {
  display: flex;
  align-items: flex-end;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.operand-group { display: flex; flex-direction: column; gap: 6px; }

.plus-mid {
  font-size: 2.2rem;
  font-weight: 900;
  color: #374151;
  padding-bottom: 6px;
  align-self: flex-end;
}

.type-toggle-row { display: flex; gap: 4px; }

.type-toggle {
  padding: 4px 12px;
  border-radius: 6px;
  border: 2px solid;
  font-size: .8rem;
  font-weight: 800;
  font-family: 'Courier New', monospace;
  cursor: pointer;
  opacity: .4;
  transition: opacity .15s, transform .1s;
  background: #fff;
}
.type-toggle:active { transform: scale(.95); }
.type-toggle.int-toggle        { border-color: var(--int-color); color: var(--int-dark); }
.type-toggle.str-toggle        { border-color: var(--str-color); color: var(--str-dark); }
.type-toggle.int-toggle.active { background: var(--int-light); opacity: 1; }
.type-toggle.str-toggle.active { background: var(--str-light); opacity: 1; }

/* ===== Diagram boxes ===== */
#plusDiagram, #convDiagram { margin-bottom: 16px; }

.diag-row {
  display: flex;
  align-items: center;
  gap: 10px;
  overflow-x: auto;
  padding: 6px 2px 8px;
}

.diag-box {
  min-width: 110px;
  padding: 14px;
  border-radius: 12px;
  border: 2.5px solid;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  text-align: center;
  flex-shrink: 0;
}
.diag-box.int-box { border-color: var(--int-color); background: var(--int-light); }
.diag-box.str-box { border-color: var(--str-color); background: var(--str-light); }
.diag-box.res-int { border-color: var(--res-color); background: var(--res-light); }
.diag-box.res-str { border-color: var(--res-color); background: var(--res-light); }
.diag-box.err-box { border-color: var(--err-color); background: var(--err-light); }

.diag-val {
  font-family: 'Courier New', monospace;
  font-size: 1.2rem;
  font-weight: 800;
  color: #1a202c;
  word-break: break-all;
  max-width: 140px;
}

.diag-op-sign {
  font-size: 1.8rem;
  font-weight: 900;
  color: #374151;
  flex-shrink: 0;
}
.diag-op-sign.error-op { color: var(--err-color); }

.diag-caption {
  font-size: .85rem;
  color: var(--muted-color);
  text-align: center;
  margin-top: 6px;
  padding: 0 4px;
}
.diag-caption.err-caption { color: var(--err-dark); font-weight: 700; }

/* Error box contents */
.err-cross { font-size: 2rem; color: var(--err-color); font-weight: 900; line-height: 1; }
.err-title { font-weight: 800; color: var(--err-dark); font-size: .9rem; }
.err-msg   { font-size: .78rem; color: var(--err-dark); line-height: 1.6; }

/* ===== Conversion (section 3) ===== */
.conv-flows {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 16px;
}

.conv-flow-row {
  display: flex;
  align-items: center;
  gap: 10px;
  overflow-x: auto;
  padding: 4px 2px;
}

.conv-arrow-col {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  flex-shrink: 0;
}

.conv-func {
  font-family: 'Courier New', monospace;
  font-size: .88rem;
  font-weight: 800;
  color: #374151;
  background: #f1f5f9;
  border: 1.5px solid #d1d5db;
  border-radius: 7px;
  padding: 4px 12px;
  white-space: nowrap;
}

.conv-arrow {
  font-size: 1.5rem;
  color: #6b7280;
  font-weight: 700;
}

/* ===== Code block ===== */
.code-block {
  background: #1e293b;
  border-radius: 10px;
  padding: 10px 16px 14px;
  margin-top: 4px;
}
.code-label {
  font-size: .68rem;
  color: #64748b;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 6px;
}
.code-block pre  { margin: 0; white-space: pre-wrap; }
.code-block code { font-family: 'Courier New', monospace; font-size: .9rem; color: #e2e8f0; line-height: 1.6; }

@media (max-width: 500px) {
  .compare-row  { grid-template-columns: 1fr; }
  .plus-controls { gap: 12px; }
}