:root {
  --bg: #080810;
  --surface: #111120;
  --surface-soft: #151528;
  --border: #1e1e35;
  --canvas-bg: #0a0a18;

  --cyan: #00f5ff;
  --purple: #bf5fff;
  --green: #00ff88;
  --amber: #f5a623;
  --red: #ff3860;

  --text: #f4f7fb;
  --muted: #8c90aa;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(
      circle at top left,
      rgba(0, 245, 255, 0.12),
      transparent 35%
    ),
    radial-gradient(
      circle at bottom right,
      rgba(191, 95, 255, 0.12),
      transparent 35%
    ),
    var(--bg);
  color: var(--text);
  font-family: "Inter", sans-serif;
}

button,
select,
input {
  font: inherit;
}

.app-shell {
  display: grid;
  grid-template-columns: 220px 1fr;
  min-height: 100vh;
}

.sidebar {
  border-right: 1px solid var(--border);
  background: rgba(17, 17, 32, 0.92);
  padding: 18px;
}

.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 28px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border: 1px solid var(--cyan);
  border-radius: 14px;
  color: var(--cyan);
  font-family: "JetBrains Mono", monospace;
  font-weight: 800;
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.25);
}

.brand h1 {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.1;
  text-transform: uppercase;
}

.brand p {
  margin: 4px 0 0;
  color: var(--muted);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
}

.category-list,
.algorithm-pills {
  display: grid;
  gap: 10px;
}

.category-btn,
.algorithm-pill,
.control-btn,
.random-btn {
  border: 1px solid var(--border);
  background: var(--surface-soft);
  color: var(--text);
  cursor: pointer;
  transition: 0.2s ease;
}

.category-btn {
  width: 100%;
  padding: 12px;
  border-radius: 12px;
  text-align: left;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.82rem;
  font-weight: 700;
}

.category-btn.active {
  border-color: var(--cyan);
  color: var(--cyan);
  box-shadow: 0 0 18px rgba(0, 245, 255, 0.2);
}

.category-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.algorithm-pills {
  margin-top: 22px;
}

.algorithm-pill {
  padding: 9px 10px;
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.78rem;
}

.algorithm-pill.active {
  border-color: var(--purple);
  color: var(--purple);
  box-shadow: 0 0 16px rgba(191, 95, 255, 0.18);
}

.main-area {
  padding: 22px;
}

.hero-panel,
.explanation-panel,
.info-card,
.canvas-card {
  border: 1px solid var(--border);
  background: rgba(17, 17, 32, 0.82);
  border-radius: 22px;
}

.hero-panel {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: center;
  padding: 22px;
  margin-bottom: 18px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--cyan);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.78rem;
  text-transform: uppercase;
}

.hero-panel h2 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 3.2rem);
  text-transform: uppercase;
  letter-spacing: -0.06em;
}

.hero-panel p {
  max-width: 650px;
  margin: 8px 0 0;
  color: var(--muted);
}

.step-counter {
  border: 1px solid var(--cyan);
  border-radius: 14px;
  padding: 12px 14px;
  color: var(--cyan);
  font-family: "JetBrains Mono", monospace;
  white-space: nowrap;
  box-shadow: 0 0 18px rgba(0, 245, 255, 0.16);
}

.studio-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 310px;
  gap: 18px;
}

.canvas-card {
  overflow: hidden;
}

canvas {
  display: block;
  width: 100%;
  height: auto;
  background: var(--canvas-bg);
}

.control-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  border-top: 1px solid var(--border);
  padding: 14px;
  background: rgba(8, 8, 16, 0.7);
}

.control-btn,
.random-btn {
  border-radius: 12px;
  padding: 10px 13px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.8rem;
}

.control-btn:hover,
.random-btn:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.control-btn.danger:hover {
  border-color: var(--red);
  color: var(--red);
}

.speed-control {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-left: auto;
  color: var(--muted);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.8rem;
}

select,
.data-input {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-soft);
  color: var(--text);
  padding: 10px;
}

.data-input {
  width: 100%;
  margin-bottom: 12px;
  font-family: "JetBrains Mono", monospace;
  outline: none;
}

.data-input:focus {
  border-color: var(--cyan);
  box-shadow: 0 0 14px rgba(0, 245, 255, 0.15);
}

.input-label {
  display: block;
  margin-bottom: 8px;
  color: var(--muted);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
}

.data-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.info-column {
  display: grid;
  gap: 18px;
  align-content: start;
}

.info-card {
  padding: 18px;
}

.info-card h3,
.explanation-panel h3 {
  margin: 0 0 14px;
  color: var(--cyan);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.9rem;
  text-transform: uppercase;
}

.info-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  margin-bottom: 14px;
}

.badge-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.complexity-badge {
  border-radius: 999px;
  padding: 7px 9px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
}

.complexity-badge.time {
  border: 1px solid var(--amber);
  color: var(--amber);
}

.complexity-badge.space {
  border: 1px solid var(--purple);
  color: var(--purple);
}

.info-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

.data-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.data-pill {
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 7px 10px;
  background: #0c0c18;
  color: var(--text);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.8rem;
}

.random-btn {
  width: 100%;
  border-color: var(--cyan);
  color: var(--cyan);
}

.random-btn.secondary {
  border-color: var(--purple);
  color: var(--purple);
}

.input-error {
  min-height: 22px;
  margin-top: 10px !important;
  color: var(--red) !important;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
}

.explanation-panel {
  margin-top: 18px;
  padding: 18px;
}

.explanation-panel p {
  margin: 0;
  color: var(--text);
  font-family: "JetBrains Mono", monospace;
  line-height: 1.7;
}

@media (max-width: 900px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

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

  .category-list,
  .algorithm-pills {
    display: flex;
    overflow-x: auto;
  }

  .category-btn,
  .algorithm-pill {
    min-width: max-content;
  }

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

  .hero-panel {
    align-items: flex-start;
    flex-direction: column;
  }

  .speed-control {
    width: 100%;
    margin-left: 0;
  }
}
.grid-tools {
  display: none;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-top: 14px;
}

.grid-tools.show {
  display: grid;
}

.grid-tool {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-soft);
  color: var(--muted);
  padding: 9px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  cursor: pointer;
  transition: 0.2s ease;
}

.grid-tool:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.grid-tool.active {
  border-color: var(--cyan);
  color: var(--cyan);
  box-shadow: 0 0 14px rgba(0, 245, 255, 0.16);
}