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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    background-color: #ffffff;
    color: #1a1a1a;
    line-height: 1.6;
}

.container {
    max-width: 1600px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    padding: 20px 0 30px;
    border-bottom: 2px solid #e0e0e0;
    margin-bottom: 30px;
}

header h1 {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 8px;
    color: #1a1a1a;
}

header h1 .red-text {
    color: #d00000;
}

header p {
    font-size: 14px;
    color: #666;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

.panel {
    background-color: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 4px;
    padding: 20px;
    min-height: 500px;
}

.panel h2 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 15px;
    color: #1a1a1a;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.tree-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.tree-header h2 {
    margin-bottom: 0;
}

.tree-header h2::after {
    content: " • Drag to Pan";
    font-size: 11px;
    color: #999;
    text-transform: none;
    font-weight: 400;
    letter-spacing: 0;
}

.reset-view-btn {
    padding: 6px 12px;
    font-size: 11px;
    background-color: #f0f0f0;
    color: #666;
    border: 1px solid #ddd;
    display: none;
}

.reset-view-btn:hover:not(:disabled) {
    background-color: #e0e0e0;
    color: #333;
}

/* Tree Visualization */
.tree-panel {
    display: flex;
    flex-direction: column;
}

#tree-svg {
    flex: 1;
    width: 100%;
    min-height: 450px;
}

/* Pseudocode Panel */
.pseudocode-panel {
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.pseudocode-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.pseudocode-header h2 {
    margin-bottom: 0;
}

.step-controls {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.step-buttons {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.step-btn {
    padding: 6px 12px;
    font-size: 12px;
    background-color: #1a1a1a;
    color: #ffffff;
}

.step-btn:hover:not(:disabled) {
    background-color: #333;
}

.step-scrubber {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.step-scrubber input[type="range"] {
    width: 100%;
}

.step-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 12px;
    color: #666;
}

.shortcut-hint {
    font-size: 11px;
    color: #888;
}

#step-summary {
    margin-bottom: 10px;
}

#pseudocode-display {
    flex: 1;
    overflow-y: auto;
    font-family: 'Courier New', monospace;
    font-size: 13px;
}

.info-text {
    color: #999;
    font-style: italic;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
}

.algorithm-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
    height: 100%;
}

.execution-bar {
    display: flex;
    gap: 20px;
    padding: 10px 12px;
    background-color: #f5f5f5;
    border: 1px solid #e0e0e0;
    border-radius: 3px;
    font-size: 11px;
    flex-wrap: wrap;
}

.exec-section {
    display: flex;
    align-items: center;
    gap: 6px;
}

.exec-label {
    font-weight: 600;
    color: #666;
    white-space: nowrap;
}

.exec-value {
    font-family: 'Courier New', monospace;
    color: #1a1a1a;
}

.step-counter {
    margin-left: auto;
    font-weight: 600;
    color: #1a1a1a;
}

.algorithm-code {
    flex: 1;
    background-color: #ffffff;
    border: 1px solid #e0e0e0;
    border-radius: 3px;
    padding: 12px;
    overflow-y: auto;
}

.algorithm-title {
    font-size: 13px;
    font-weight: 600;
    color: #666;
    margin-bottom: 10px;
    padding-bottom: 8px;
    border-bottom: 1px solid #e0e0e0;
}

.code-line {
    padding: 3px 0;
    display: flex;
    align-items: flex-start;
    line-height: 1.5;
}

.code-line.active {
    background-color: #1a1a1a;
    color: #ffffff;
    margin: 0 -12px;
    padding: 3px 12px;
    border-radius: 2px;
}

.line-number {
    display: inline-block;
    min-width: 32px;
    color: #999;
    font-size: 11px;
    text-align: right;
    margin-right: 16px;
    user-select: none;
    flex-shrink: 0;
}

.code-line.active .line-number {
    color: #888;
}

.line-text {
    white-space: pre;
    flex: 1;
}

/* Control Panel */
.control-panel {
    background-color: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 4px;
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.control-group h3 {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 12px;
    color: #1a1a1a;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Operation Controls */
.operation-controls {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.operation-row {
    display: flex;
    align-items: center;
    gap: 4px;
}

.op-name {
    font-family: 'Courier New', monospace;
    font-size: 15px;
    font-weight: 600;
    color: #1a1a1a;
}

.op-input {
    width: 80px;
    padding: 4px 8px;
    border: 1px solid #ccc;
    border-radius: 3px;
    font-size: 14px;
    font-family: 'Courier New', monospace;
    background-color: #ffffff;
    color: #1a1a1a;
    text-align: center;
}

.op-input:focus {
    outline: none;
    border-color: #1a1a1a;
}

.op-input::placeholder {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    font-size: 12px;
    font-style: italic;
}

.go-btn {
    padding: 6px 14px;
    font-size: 18px;
    background-color: #1a1a1a;
    color: #ffffff;
    margin-left: 6px;
}

.go-btn:hover:not(:disabled) {
    background-color: #333;
}

input[type="number"] {
    padding: 8px 12px;
    border: 1px solid #ccc;
    border-radius: 3px;
    font-size: 14px;
    background-color: #ffffff;
    color: #1a1a1a;
}

input[type="number"]:focus {
    outline: none;
    border-color: #1a1a1a;
}

button {
    padding: 8px 16px;
    background-color: #1a1a1a;
    color: #ffffff;
    border: none;
    border-radius: 3px;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover:not(:disabled) {
    background-color: #333;
}

button:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

#clear-btn {
    background-color: #666;
    margin-top: 8px;
}

#clear-btn:hover:not(:disabled) {
    background-color: #888;
}

/* Animation Controls */
.animation-controls {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.speed-control {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 8px;
}

.speed-control label {
    font-size: 13px;
    color: #666;
}

input[type="range"] {
    flex: 1;
    height: 4px;
    background: #e0e0e0;
    border-radius: 2px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 14px;
    height: 14px;
    background: #1a1a1a;
    border-radius: 50%;
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    width: 14px;
    height: 14px;
    background: #1a1a1a;
    border-radius: 50%;
    cursor: pointer;
    border: none;
}

#speed-label {
    font-size: 12px;
    color: #666;
    min-width: 60px;
}

/* Tree Stats */
#tree-stats {
    display: flex;
    flex-direction: column;
    gap: 8px;
    font-size: 14px;
    color: #666;
}

#tree-stats strong {
    color: #1a1a1a;
}

#operation-status {
    margin-top: 8px;
    padding: 8px;
    background-color: #ffffff;
    border-radius: 3px;
    font-size: 12px;
    min-height: 20px;
}

/* Tree Nodes and Edges (D3 visualization) */
.node circle {
    fill: #ffffff;
    stroke: #1a1a1a;
    stroke-width: 2.5px;
}

.node text {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    font-size: 15px;
    font-weight: 600;
    fill: #1a1a1a;
    text-anchor: middle;
    dominant-baseline: middle;
    pointer-events: none;
}

.var-pointer-text {
    font-family: 'Courier New', monospace;
    font-size: 14px;
    font-weight: 600;
    fill: #2d9f2d;
    text-anchor: start;
    dominant-baseline: middle;
    pointer-events: none;
}

.link {
    stroke-width: 3.5px;
}

.link.black {
    stroke: #1a1a1a;
}

.link.red {
    stroke: #d00000;
    /* Sedgewick's exact color: rgb(175, 61, 39) */
}

.floating-label {
    font-size: 11px;
    fill: #666;
}

.floating-box {
    fill: rgba(240, 240, 240, 0.9);
    stroke: #dcdcdc;
    stroke-width: 1.5px;
}

/* About Section */
.about-section {
    margin-top: 30px;
    padding: 20px;
    text-align: center;
    border-top: 1px solid #e0e0e0;
}

.about-section p {
    font-size: 13px;
    color: #666;
    line-height: 1.6;
}

.about-section a {
    color: #1a1a1a;
    text-decoration: none;
    border-bottom: 1px solid #ccc;
}

.about-section a:hover {
    color: #000;
    border-bottom-color: #1a1a1a;
}

/* Responsive */
@media (max-width: 1200px) {
    .main-content {
        grid-template-columns: 1fr;
    }

    .control-panel {
        grid-template-columns: 1fr;
    }
}