.letter-rules-page {
  min-height: 100vh;
  padding: 32px 20px 64px;
  background:
    radial-gradient(circle at 82% 4%, rgba(34, 197, 94, 0.1), transparent 26rem),
    var(--bg);
}

.letter-rules-shell {
  width: min(1040px, 100%);
  margin: 0 auto;
}

.letter-rules-hero {
  max-width: 800px;
  padding: clamp(30px, 5vw, 52px) 0 30px;
}

.letter-rules-hero h1 {
  margin: 6px 0 16px;
  font-size: clamp(2.25rem, 6vw, 4.25rem);
  line-height: 1;
  letter-spacing: -0.05em;
}

.letter-rules-hero > p:last-child {
  max-width: 720px;
  margin: 0;
  color: var(--text-secondary);
  font-size: 1.08rem;
  line-height: 1.72;
}

.letter-rules-lab {
  display: grid;
  grid-template-columns: 0.86fr 1.14fr;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--panel);
  box-shadow: var(--shadow-3);
}

.letter-rules-lab__controls,
.letter-rules-lab__result {
  padding: clamp(22px, 5vw, 42px);
}

.letter-rules-lab__controls {
  border-right: 1px solid var(--border);
}

.letter-rules-lab h2,
.letter-rules-steps h2,
.letter-rules-examples h2 {
  margin: 3px 0 12px;
  font-size: clamp(1.55rem, 4vw, 2.45rem);
  letter-spacing: -0.04em;
}

.letter-rules-lab__controls > p:not(.section-kicker) {
  color: var(--text-secondary);
  line-height: 1.6;
}

.letter-rules-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin: 20px 0 12px;
}

.letter-rules-inputs label {
  display: grid;
  gap: 7px;
  color: var(--text-secondary);
  font-size: var(--text-sm);
  font-weight: 700;
}

.letter-rules-inputs input {
  min-width: 0;
  height: 49px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--input-bg);
  color: var(--text);
  font: 700 1rem/1 var(--font-display);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.letter-rules-inputs input:focus {
  border-color: var(--accent);
  outline: 3px solid var(--accent-soft);
}

.letter-rules-contrast {
  display: block;
  margin-top: 13px;
  padding: 0;
  border: 0;
  background: none;
  color: var(--text-secondary);
  cursor: pointer;
  font: inherit;
  font-size: var(--text-sm);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.letter-rules-error {
  margin: 12px 0 0;
  color: var(--danger);
  font-size: var(--text-sm);
}

.letter-rules-lab__result {
  display: flex;
  min-height: 390px;
  flex-direction: column;
  justify-content: center;
  background: linear-gradient(150deg, var(--panel-2), var(--panel));
}

.letter-rules-tiles,
.letter-rules-example__tiles {
  display: flex;
  gap: 7px;
}

.letter-rules-tiles {
  justify-content: center;
  margin-bottom: 26px;
}

.letter-rules-tiles span,
.letter-rules-example__tiles span {
  display: grid;
  place-items: center;
  border-radius: 6px;
  color: #fff;
  font: 700 1.35rem/1 var(--font-display);
}

.letter-rules-tiles span {
  width: clamp(48px, 9vw, 62px);
  aspect-ratio: 1;
}

.letter-rules-tiles .is-correct,
.letter-rules-example__tiles .is-correct {
  background: var(--green);
  color: var(--on-accent);
}

.letter-rules-tiles .is-present,
.letter-rules-example__tiles .is-present {
  background: var(--yellow-dark);
}

.letter-rules-tiles .is-absent,
.letter-rules-example__tiles .is-absent {
  background: #57534e;
  color: #fff;
}

.letter-rules-page.is-high-contrast .is-correct {
  background: #2563eb;
  color: #fff;
}

.letter-rules-page.is-high-contrast .is-present {
  background: #c2410c;
  color: #fff;
}

.letter-rules-explanations {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 24px;
  color: var(--text-secondary);
}

.letter-rules-explanations li::marker {
  color: var(--accent);
  font-weight: 800;
}

.letter-rules-steps,
.letter-rules-examples {
  margin-top: 24px;
  padding: clamp(24px, 5vw, 42px);
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--panel);
}

.letter-rules-step-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 24px;
}

.letter-rules-step-grid article {
  padding: 18px;
  border-radius: var(--radius-lg);
  background: var(--panel-2);
}

.letter-rules-step-grid article > span {
  color: var(--accent);
  font: 700 var(--text-sm)/1 var(--font-display);
}

.letter-rules-step-grid h3 {
  margin: 12px 0 7px;
}

.letter-rules-step-grid p {
  margin: 0;
  color: var(--text-secondary);
  line-height: 1.6;
}

.letter-rules-example-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 20px;
}

.letter-rules-example {
  display: grid;
  gap: 12px;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--panel-2);
  color: var(--text-secondary);
  cursor: pointer;
  font: inherit;
  line-height: 1.55;
  text-align: left;
}

.letter-rules-example:hover,
.letter-rules-example:focus-visible {
  border-color: var(--accent);
}

.letter-rules-example__words {
  color: var(--text);
  font: 700 1rem/1 var(--font-display);
  letter-spacing: 0.05em;
}

.letter-rules-example__tiles span {
  width: 30px;
  height: 30px;
  font-size: 0.8rem;
}

.letter-rules-shell > .related-tools {
  margin-top: 24px;
}

@media (max-width: 760px) {
  .letter-rules-page {
    padding: 20px 12px 48px;
  }

  .letter-rules-lab {
    grid-template-columns: 1fr;
  }

  .letter-rules-lab__controls {
    border-right: 0;
    border-bottom: 1px solid var(--border);
  }

  .letter-rules-step-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 540px) {
  .letter-rules-inputs,
  .letter-rules-example-grid {
    grid-template-columns: 1fr;
  }
}