:root {
  --bg-color: #0d1117;
  --panel-bg: #161b22;
  --card-bg: #1c2128;
  --border-color: #30363d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  
  --bar-unsorted: #58a6ff;
  --bar-comparing: #f85149;
  --bar-swapping: #d29922;
  --bar-sorted: #3fb950;

  --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; }
.highlight { color: var(--accent-color); font-weight: 600; }

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: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  height: calc(100vh - 100px);
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
}

button {
  cursor: pointer;
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 6px;
  padding: 0.65rem 1.2rem;
  transition: 0.2s;
}

.primary-btn { background-color: #238636; color: #fff; border: 1px solid rgba(240, 246, 252, 0.1); }
.primary-btn:hover { background-color: #2ea043; }
.primary-btn:disabled { background-color: #23482b; color: #8b949e; cursor: not-allowed; }

.secondary-btn { background-color: var(--panel-bg); color: var(--text-primary); border: 1px solid var(--border-color); }
.secondary-btn:hover { background-color: #30363d; border-color: #8b949e; }
.secondary-btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* Top Controls */
.controls {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1.5rem;
  align-items: center;
}

.control-group {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  flex-wrap: wrap;
}

.slider-wrapper {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  width: 150px;
}
.slider-wrapper label { font-size: 0.875rem; color: var(--text-secondary); }

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; }

.alg-buttons {
  display: flex;
  gap: 0.5rem;
  background-color: var(--panel-bg);
  padding: 0.25rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}
.alg-btn { background: transparent; border: none; color: var(--text-secondary); padding: 0.5rem 1rem;}
.alg-btn:hover { color: var(--text-primary); }
.alg-btn.active { background: var(--card-bg); color: var(--text-primary); box-shadow: 0 1px 3px rgba(0,0,0,0.5); }
.alg-btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* Visualizer Domain */
.visualizer-container {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}
#sort-status { font-weight: 500; font-size: 1.1rem; }

.legend { display: flex; gap: 1rem; font-size: 0.875rem; }
.legend-item { display: flex; align-items: center; gap: 0.35rem; color: var(--text-secondary); }
.dot { width: 10px; height: 10px; border-radius: 50%; }
.dot.unsorted { background-color: var(--bar-unsorted); }
.dot.comparing { background-color: var(--bar-comparing); }
.dot.swapping { background-color: var(--bar-swapping); }
.dot.sorted { background-color: var(--bar-sorted); }

.array-canvas {
  flex-grow: 1;
  display: flex;
  align-items: flex-end; /* Align bars to bottom */
  justify-content: center;
  gap: 2px;
  padding: 1rem 0;
}

.array-bar {
  background-color: var(--bar-unsorted);
  width: 100%; /* controlled flexibly via flexbox container */
  border-radius: 3px 3px 0 0;
  transition: height 0.1s ease; /* Smooth height changes if resizing, color is instant */
}