@import url("https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=IBM+Plex+Serif:wght@500;600;700&display=swap");

:root {
  --bg-1: #f3ede7;
  --bg-2: #dbe6f2;
  --ink: #1d1c1a;
  --muted: #5f5b57;
  --accent: #f15f4a;
  --accent-dark: #c44836;
  --grid: #2c2a27;
  --soft: #f7f2ee;
  --shadow: 0 20px 40px rgba(22, 20, 18, 0.15);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Space Grotesk", "Trebuchet MS", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(241, 95, 74, 0.2), transparent 55%),
    linear-gradient(120deg, var(--bg-1), var(--bg-2));
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.page {
  max-width: 1300px;
  margin: 0 auto;
  padding: 28px 20px 64px;
  display: grid;
  gap: 28px;
}

.hero {
  display: grid;
  gap: 16px;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.2em;
  font-size: 12px;
  margin: 0 0 12px;
  color: var(--muted);
}

h1 {
  font-family: "IBM Plex Serif", "Times New Roman", serif;
  font-size: clamp(1.8rem, 2.6vw, 2.6rem);
  margin: 0;
}

.lead {
  font-size: 1.1rem;
  margin: 0;
  color: var(--muted);
  max-width: 36ch;
}

.hero__panel {
  background: var(--soft);
  border-radius: 0;
  padding: 24px;
  box-shadow: var(--shadow);
  display: grid;
  gap: 16px;
  grid-template-rows: auto 1fr auto;
}

.panel__status {
  font-weight: 600;
  font-size: 1rem;
}

.panel__actions {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}

.panel__notes {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--muted);
}

.panel__section {
  display: grid;
  gap: 16px;
}

.solve-panel {
  display: grid;
  gap: 10px;
  padding: 14px;
  border-radius: 0;
  border: 1px solid rgba(44, 42, 39, 0.2);
  background: rgba(255, 255, 255, 0.65);
  align-self: end;
}

.solve-panel__actions {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}

.solve-panel__hint {
  font-size: 0.85rem;
  color: var(--muted);
  min-height: 1.4em;
}

.solve-panel__title {
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.75rem;
  color: var(--muted);
}

.solve-panel__log {
  margin: 0;
  padding-left: 0;
  display: grid;
  gap: 6px;
  font-size: 0.82rem;
  color: var(--muted);
  max-height: 180px;
  overflow: auto;
  list-style: none;
}

.segmented {
  display: inline-flex;
  border: 1px solid var(--grid);
  background: rgba(255, 255, 255, 0.7);
}

.segmented__option {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding: 8px 14px;
  cursor: pointer;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.75rem;
  color: var(--ink);
}

.segmented__option input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.segmented__option input:checked + span {
  background: var(--ink);
  color: white;
  padding: 8px 14px;
  margin: -8px -14px;
}

.segmented__option span {
  display: inline-flex;
  align-items: center;
}

.btn {
  border: 1px solid var(--grid);
  background: rgba(255, 255, 255, 0.75);
  color: var(--ink);
  padding: 10px 12px;
  border-radius: 0;
  cursor: pointer;
  font-weight: 600;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn--small {
  padding: 4px 8px;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  border-radius: 0;
}

.btn--accent {
  background: var(--accent);
  border-color: var(--accent-dark);
  color: white;
}

.select {
  border: 1px solid var(--grid);
  background: white;
  color: var(--ink);
  padding: 8px 10px;
  font-weight: 600;
  font-family: "Space Grotesk", "Trebuchet MS", sans-serif;
}

.select--small {
  padding: 6px 8px;
  font-size: 0.85rem;
}

.difficulty {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 20px rgba(29, 28, 26, 0.2);
}

.btn--primary {
  background: var(--accent);
  border-color: var(--accent-dark);
  color: white;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(440px, 595px);
  gap: 36px;
  align-items: start;
}

.left-column {
  display: grid;
  gap: 28px;
}

.utility-row {
  width: 100%;
  display: grid;
  gap: 8px;
  background: rgba(44, 42, 39, 0.06);
  border-radius: 0;
  padding: 8px 10px;
  margin-inline: auto;
}

.utility-row__group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
  justify-content: space-between;
}

.board {
  display: grid;
  gap: 14px;
  justify-items: center;
  background: rgba(255, 255, 255, 0.6);
  border-radius: 0;
  padding: 20px 22px;
  box-shadow: var(--shadow);
  width: min(88vw, 520px);
  margin-inline: auto;
}

.control-bar {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 6px 8px;
  border: 1px solid rgba(44, 42, 39, 0.2);
  background: rgba(255, 255, 255, 0.75);
  margin-inline: auto;
}

.toggle-inline {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.toggle-inline input {
  accent-color: var(--accent);
}

.keypad {
  display: grid;
  grid-template-columns: repeat(9, minmax(0, 1fr));
  gap: 6px;
  width: 100%;
  margin-inline: auto;
}

.keypad__btn {
  padding: 8px 0;
}

.grid {
  display: grid;
  grid-template-columns: repeat(9, minmax(36px, 1fr));
  width: 100%;
  aspect-ratio: 1;
  border: 3px solid var(--grid);
  background: white;
  box-shadow: var(--shadow);
  overflow: hidden;
  animation: fadeIn 0.6s ease;
  margin-inline: auto;
}

.cell {
  border: 1px solid rgba(44, 42, 39, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.cell:nth-child(3n) {
  border-right: 3px solid var(--grid);
}

.cell:nth-child(n + 19):nth-child(-n + 27),
.cell:nth-child(n + 46):nth-child(-n + 54) {
  border-bottom: 3px solid var(--grid);
}

.cell input {
  width: 100%;
  height: 100%;
  border: none;
  text-align: center;
  font-size: clamp(1.1rem, 3vw, 1.6rem);
  font-weight: 600;
  font-family: "Space Grotesk", "Trebuchet MS", sans-serif;
  background: transparent;
  color: var(--ink);
  position: relative;
  z-index: 2;
  caret-color: transparent;
}

.candidates {
  position: absolute;
  inset: 6px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  font-size: 0.55rem;
  color: var(--muted);
  opacity: 0;
  transition: opacity 0.2s ease;
  z-index: 1;
  pointer-events: none;
}

.candidates span {
  display: flex;
  align-items: center;
  justify-content: center;
}

.grid.show-candidates .candidates {
  opacity: 1;
}

.candidates.manual-visible {
  opacity: 1;
}

.candidates span.manual {
  color: #11422a;
  font-weight: 600;
}

.cell input:focus {
  outline: 2px solid var(--accent);
  background: rgba(241, 95, 74, 0.08);
}

.cell.invalid input {
  background: rgba(241, 95, 74, 0.18);
  color: #b3261e !important;
}

.cell.prefilled input {
  color: #000000;
}

.cell.user-filled input {
  color: #1e5bd8;
}

.cell.step-solved input {
  color: #7a2de2;
}

.cell.hint-target input {
  background: rgba(84, 144, 255, 0.2);
}

.cell.candidate-changed input {
  background: rgba(255, 200, 120, 0.35);
}

.cell.highlight input {
  background: rgba(255, 214, 102, 0.35);
}

.cell.match input {
  background: rgba(88, 201, 122, 0.35);
  color: #11422a;
}

.cell.selected input {
  background: rgba(84, 144, 255, 0.3);
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .page {
    padding: 16px 16px 48px;
    gap: 20px;
  }

  h1 {
    font-size: clamp(1.5rem, 6vw, 2rem);
  }

  .panel__notes {
    flex-direction: column;
    gap: 6px;
  }

  .workspace {
    grid-template-columns: 1fr;
  }

  .left-column {
    display: contents;
  }

  .board {
    order: 1;
  }

  .hero__panel {
    order: 2;
  }

  .tactics {
    order: 3;
  }

  .board {
    justify-content: center;
  }
}

.tactics {
  background: rgba(255, 255, 255, 0.6);
  border-radius: 0;
  padding: 20px 22px;
  box-shadow: var(--shadow);
}

.tactics h2 {
  margin: 0 0 12px;
  font-size: 1.2rem;
}

.tactic {
  display: grid;
  gap: 6px;
  padding: 10px 0;
  border-top: 1px solid rgba(44, 42, 39, 0.12);
}

.tactic:first-of-type {
  border-top: none;
}

.tactic h3 {
  margin: 0;
  font-size: 1rem;
}

.tactic p {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}