:root {
  --bg-color: #0d1117;
  --panel-bg: #161b22;
  --card-bg: #1c2128;
  --border-color: #30363d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  --success-color: #3fb950;
  --error-color: #f85149;
  
  --chunk-1: rgba(88, 166, 255, 0.2);
  --chunk-2: rgba(63, 185, 80, 0.2);
  --chunk-3: rgba(210, 153, 34, 0.2);
  --chunk-4: rgba(248, 81, 73, 0.2);
  --chunk-5: rgba(188, 140, 255, 0.2);

  --font-sans: 'Inter', -apple-system, sans-serif;
  --font-mono: 'Fira Code', ui-monospace, SFMono-Regular, monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
}

.code-font { font-family: var(--font-mono); font-size: 14px; }
.mt-2 { margin-top: 1rem; }
.mt-4 { margin-top: 2rem; }
.flex-grow { flex-grow: 1; }

header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  border-bottom: 1px solid var(--border-color);
  padding: 1.5rem 2rem;
}

.header-left h1 { font-size: 1.5rem; font-weight: 600; margin-top: 0.5rem; }
.header-right p { color: var(--text-secondary); font-size: 0.875rem; }

.back-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s;
  display: inline-block;
  margin-bottom: 0.5rem;
}
.back-link:hover { color: var(--accent-color); }

.main-content {
  padding: 2rem;
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  min-height: calc(100vh - 100px);
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
}
.card h2 { font-size: 1.125rem; font-weight: 600; margin-bottom: 1rem; color: #fff; }

/* Selection Buttons */
.algorithm-selector {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.5rem;
}

.alg-btn {
  background-color: var(--panel-bg);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  padding: 0.75rem 1.25rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
  font-weight: 500;
  transition: all 0.2s;
}

.alg-btn:hover { border-color: var(--text-secondary); color: var(--text-primary); }
.alg-btn.active { background-color: rgba(88, 166, 255, 0.1); border-color: var(--accent-color); color: var(--accent-color); }

/* Input */
.header-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.header-row label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-transform: uppercase;
}

.text-btn {
  background: transparent;
  border: none;
  color: var(--accent-color);
  cursor: pointer;
  font-size: 0.875rem;
}
.text-btn:hover { text-decoration: underline; }
.text-btn.danger { color: var(--error-color); }

textarea {
  width: 100%;
  height: 120px;
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  padding: 1rem;
  resize: vertical;
  outline: none;
  line-height: 1.5;
}
textarea:focus { border-color: var(--accent-color); }

/* TTTD Controls */
.tttd-controls {
  margin-top: 1rem;
  padding: 1rem;
  background-color: var(--panel-bg);
  border-radius: 6px;
  border: 1px solid var(--border-color);
}
.control-row { display: flex; gap: 2rem; }
.control-item { display: flex; flex-direction: column; flex-grow: 1; }
.control-item label { font-size: 0.8rem; color: var(--text-secondary); margin-bottom: 0.5rem; display: flex; justify-content: space-between;}
.control-item span.val { color: var(--accent-color); font-family: var(--font-mono);}

input[type=range] { -webkit-appearance: none; appearance: none; width: 100%; background: transparent; }
input[type=range]::-webkit-slider-thumb { -webkit-appearance: none; appearance:none; height: 16px; width: 16px; border-radius: 50%; background: var(--accent-color); cursor: pointer; margin-top: -6px; }
input[type=range]::-webkit-slider-runnable-track { width: 100%; height: 4px; cursor: pointer; background: var(--border-color); border-radius: 2px; }

/* Metrics */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.metric-box {
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.metric-label { font-size: 0.875rem; color: var(--text-secondary); margin-bottom: 0.5rem; text-transform: uppercase; }
.metric-value { font-size: 1.5rem; color: var(--text-primary); font-weight: 700; }
.metric-value.highlight { color: var(--success-color); }

/* Visualization */
.output-block {
  min-height: 100px;
  max-height: 200px;
  overflow-y: auto;
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  word-break: break-all;
  white-space: pre-wrap;
}

.visual-block {
  min-height: 150px;
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1.5rem;
  overflow-x: auto;
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 0.5rem;
}

.empty-state {
  color: var(--text-secondary);
  font-style: italic;
  font-size: 0.875rem;
  width: 100%;
  text-align: center;
}

/* Data Structure Styling */
.visual-chip {
  display: inline-block;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  background-color: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
}

.chunk { border-left: 3px solid transparent; }
.chunk-0 { background-color: var(--chunk-1); border-left-color: #58a6ff; }
.chunk-1 { background-color: var(--chunk-2); border-left-color: #3fb950; }
.chunk-2 { background-color: var(--chunk-3); border-left-color: #d29922; }
.chunk-3 { background-color: var(--chunk-4); border-left-color: #f85149; }
.chunk-4 { background-color: var(--chunk-5); border-left-color: #bc8cff; }

/* Tables */
table { width: 100%; border-collapse: collapse; font-family: var(--font-mono); font-size: 0.875rem; }
th, td { border: 1px solid var(--border-color); padding: 0.5rem; text-align: left; }
th { background-color: rgba(255,255,255,0.05); color: var(--text-secondary); }
td.dict-code { color: #df8e1d; }

/* Tree Nodes */
.tree-container {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  width: 100%;
}
.tree-row { display: flex; justify-content: space-between; padding: 0.25rem 0; border-bottom: 1px dashed var(--border-color); }
.tree-row:last-child { border-bottom: none; }
.tree-code { color: var(--success-color); }