.collatz-page {
  --c-ink: #182528;
  --c-muted: #647476;
  --c-line: #dce6e1;
  --c-accent: #117864;
  color: var(--c-ink);
  background: #f5f8f5;
  padding: 70px 20px 100px;
  min-height: 80vh;
}

.collatz-page * { box-sizing: border-box; }
.collatz-shell { max-width: 1120px; margin: 0 auto; }
.collatz-intro { max-width: 760px; margin-bottom: 35px; }
.collatz-kicker, .collatz-eyebrow {
  color: var(--c-accent);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .13em;
  text-transform: uppercase;
}
.collatz-intro h1 {
  font-size: clamp(36px, 5vw, 66px);
  line-height: 1.08;
  letter-spacing: -.045em;
  font-weight: 750;
  margin: 16px 0 18px;
}
.collatz-intro h1 span { color: var(--c-accent); }
.collatz-intro p { color: var(--c-muted); font-size: 18px; line-height: 1.65; margin: 0; }
.collatz-panel {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: 20px;
  box-shadow: 0 12px 34px rgba(32, 73, 57, .045);
}
.collatz-controls { display: grid; grid-template-columns: 1fr 1.2fr; gap: 46px; padding: 34px 38px; align-items: center; }
.collatz-controls h2, .collatz-section-heading h2 { margin: 0 0 9px; font-size: 24px; font-weight: 700; letter-spacing: -.025em; }
.collatz-controls p { margin: 0; color: var(--c-muted); line-height: 1.55; }
.collatz-controls label { display: block; margin-bottom: 9px; font-weight: 650; font-size: 14px; }
.collatz-input-row { display: flex; gap: 9px; }
.collatz-input-row input {
  min-width: 0;
  flex: 1;
  height: 50px;
  border: 1px solid #cad9d0;
  border-radius: 10px;
  background: #fbfdfb;
  padding: 0 15px;
  color: var(--c-ink);
  font-size: 17px;
  outline: none;
}
.collatz-input-row input:focus { border-color: var(--c-accent); box-shadow: 0 0 0 3px rgba(17, 120, 100, .12); }
.collatz-input-row input[aria-invalid="true"] { border-color: #be453b; }
.collatz-input-row button {
  border: 0;
  border-radius: 10px;
  background: var(--c-accent);
  color: #fff;
  padding: 0 18px;
  font-size: 14px;
  font-weight: 700;
  white-space: nowrap;
  cursor: pointer;
}
.collatz-input-row button:hover { background: #0c5c4c; }
.collatz-input-row button span { font-size: 18px; margin-left: 8px; }
.collatz-error { color: #b53e35 !important; font-size: 13px; margin-top: 8px !important; }
.collatz-examples { display: flex; gap: 8px; align-items: center; margin-top: 14px; color: var(--c-muted); font-size: 13px; }
.collatz-examples button { border: 1px solid var(--c-line); border-radius: 7px; background: #f7faf7; padding: 3px 10px; color: var(--c-accent); cursor: pointer; }
.collatz-examples button:hover { border-color: var(--c-accent); }
.collatz-stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin: 20px 0; }
.collatz-stat { background: #e8f2ec; border: 1px solid #d9e8dd; border-radius: 14px; padding: 18px 20px; min-width: 0; }
.collatz-stat span { display: block; color: #5a7169; font-size: 13px; margin-bottom: 5px; }
.collatz-stat strong { display: block; font-size: 20px; line-height: 1.3; overflow-wrap: anywhere; }
.collatz-chart-panel, .collatz-table-panel { padding: 30px 34px; margin-top: 20px; }
.collatz-section-heading { display: flex; justify-content: space-between; align-items: end; gap: 20px; }
.collatz-section-heading h2 { margin: 6px 0 0; }
.collatz-range { color: var(--c-muted); font-size: 13px; white-space: nowrap; }
.collatz-table-actions { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.collatz-table-actions button { border: 1px solid #b7d8c8; border-radius: 8px; background: #eff7f1; color: var(--c-accent); padding: 8px 12px; font-size: 13px; font-weight: 650; cursor: pointer; }
.collatz-table-actions button:hover, .collatz-table-actions button[aria-pressed="true"] { background: #dcefe4; border-color: #8bbda3; }
.collatz-formula { display: inline-block; background: #eff6f0; color: #245f50; padding: 8px 13px; border-radius: 8px; margin: 22px 0 16px; font-size: 15px; }
.collatz-chart-note { color: var(--c-muted); font-size: 13px; line-height: 1.5; margin: -4px 0 16px; }
.collatz-zoom-control { display: flex; align-items: center; gap: 14px; margin: 0 0 18px; color: var(--c-muted); font-size: 13px; }
.collatz-zoom-control label { white-space: nowrap; }
.collatz-zoom-control input { flex: 1; min-width: 80px; accent-color: var(--c-accent); cursor: pointer; }
.collatz-zoom-control output { min-width: 32px; color: var(--c-accent); font-weight: 700; text-align: right; }
.collatz-chart-wrap { width: 100%; overflow-x: auto; overflow-y: hidden; background: #fcfefc; border: 1px solid #e8eee8; border-radius: 10px; padding: 12px; }
#collatz-chart { width: 100%; height: 340px; display: block; overflow: visible; }
.collatz-grid-line { stroke: #e5eee8; stroke-width: 1; }
.collatz-grid-label { fill: #7b8d85; font: 12px sans-serif; }
.collatz-point { fill: #fff; stroke: #13866e; stroke-width: 2; vector-effect: non-scaling-stroke; }
.collatz-axis { display: flex; justify-content: space-between; color: var(--c-muted); font-size: 12px; margin: 10px 4px 0; }
.collatz-table-scroll { max-height: 500px; overflow: auto; margin-top: 22px; border: 1px solid var(--c-line); border-radius: 10px; }
.collatz-table-panel table { width: 100%; min-width: 880px; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.collatz-table-panel th, .collatz-table-panel td { text-align: left; padding: 11px 16px; border-bottom: 1px solid #edf1ed; }
.collatz-table-panel th { position: sticky; top: 0; z-index: 1; background: #f3f8f3; color: #52685d; font-size: 13px; white-space: nowrap; }
.collatz-table-panel td { font-size: 14px; overflow-wrap: anywhere; }
.collatz-d-expression { display: inline-flex; align-items: center; gap: 5px; white-space: nowrap; }
.collatz-fraction { display: inline-flex; flex-direction: column; align-items: stretch; text-align: center; line-height: 1.15; white-space: nowrap; font-size: 13px; }
.collatz-fraction span:first-child { border-bottom: 1px solid currentColor; padding: 0 4px 2px; }
.collatz-fraction span:last-child { padding: 2px 4px 0; }
.collatz-d-note { color: var(--c-muted); font-size: 12px; line-height: 1.5; margin: 12px 0 0; }
.collatz-table-panel tr:last-child td { border-bottom: 0; }
.collatz-table-panel tbody tr:hover { background: #f8fbf8; }
.collatz-table-panel tbody tr[hidden] { display: none; }
@media (max-width: 800px) {
  .collatz-page { padding: 42px 16px 70px; }
  .collatz-controls { grid-template-columns: 1fr; gap: 22px; padding: 25px; }
  .collatz-stats { grid-template-columns: repeat(2, 1fr); }
  .collatz-chart-panel, .collatz-table-panel { padding: 23px; }
}
@media (max-width: 520px) {
  .collatz-zoom-control { flex-wrap: wrap; gap: 8px; }
  .collatz-zoom-control label { width: 100%; }
  .collatz-intro p { font-size: 16px; }
  .collatz-input-row { flex-direction: column; }
  .collatz-input-row button { height: 48px; }
  .collatz-stat { padding: 13px; }
  .collatz-stat strong { font-size: 16px; }
  .collatz-section-heading { align-items: start; flex-direction: column; gap: 5px; }
  #collatz-chart { height: 270px; }
  .collatz-table-panel th, .collatz-table-panel td { padding: 9px 11px; }
}