/* The Thinking Experiment - Atwood Machine Styles */

:root {

  --bg-950: #e9f4fb;
  --bg-900: #fff4dd;
  --bg-800: #ffffff;
  --text-100: #123140;
  --text-300: #4b6570;
  --gold-500: #0f7e9b;
  --gold-400: #0b5f77;
  --surface: rgba(255, 255, 255, 0.96);
  --border: #c8dbe3;
  --shadow-lg: 0 12px 24px rgba(12, 54, 68, 0.12);

    /* Light theme - blue/teal palette */
    --primary-color: #123140;
    --secondary-color: #0f7e9b;
    --accent-color: #13a1c4;
    --light-bg: #e9f4fb;
    --dark-text: #123140;
    --light-text: #4b6570;
    --border-color: #c8dbe3;
    --success-color: #1a7f4e;
    --warning-color: #9a5d00;
    --background-color: #ffffff;

}



/* Former theme overrides now applied in the single light theme */
.info-item {
    background: var(--background-color);
}

.control-group input[type="number"],
.control-group input[type="text"] {
    background: var(--background-color);
    color: var(--dark-text);
    border-color: var(--border-color);
}

details {
    background: var(--background-color);
}

details summary {
    color: var(--dark-text);
}

.visualization-toggles {
    background-color: var(--background-color);
}

.checkbox-label {
    color: var(--dark-text);
}

.exploration-content,
.theory-content {
    background: var(--background-color);
    color: var(--dark-text);
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Performance optimization: GPU acceleration for smooth animations */
canvas {
    will-change: transform;
    transform: translateZ(0);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--light-bg);
    color: var(--dark-text);
    line-height: 1.7;
    min-height: 100vh;
    /* Optimize font rendering */
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}



.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

header {
    position: relative;
    text-align: center;
    background-color: var(--background-color);
    margin-bottom: 20px;
    padding: 25px 20px;
    border-bottom: 3px solid var(--secondary-color);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 2em;
    margin-bottom: 8px;
    color: var(--primary-color);
    font-weight: 700;
}

.subtitle {
    font-size: 1em;
    color: var(--light-text);
}

.main-content {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-bottom: 20px;
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.simulation-panel {
    background: var(--background-color);
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    border: 1px solid var(--border-color);
}

.simulation-container {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 380px;
    gap: 25px;
    align-items: start;
}

.canvas-area {
    position: relative;
    display: flex;
    gap: 10px;
    align-items: flex-start;
    justify-content: flex-start;
    max-width: 100%;
    overflow: visible;
}

#atwoodCanvas {
    display: block;
    width: 700px;
    height: 650px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background: linear-gradient(to bottom, #f0f8ff 0%, #ffffff 100%);
    flex-shrink: 0;
}

.controls {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.info-panel {
    background: var(--background-color);
    border-radius: 8px;
    padding: 30px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    border: 1px solid var(--border-color);
}

.controls-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 12px;
    margin-bottom: 15px;
}

.control-group {
    margin-bottom: 0;
    padding: 12px;
    background: var(--light-bg);
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.control-group label {
    display: block;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 8px;
    font-size: 0.95em;
}

.control-group input[type="number"] {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1em;
    margin-bottom: 5px;
}

.control-group input[type="range"] {
    width: 100%;
    margin: 8px 0;
}

.control-group input[type="number"]:focus,
.control-group input[type="range"]:focus {
    outline: none;
    border-color: var(--secondary-color);
}

.value-display {
    font-weight: 600;
    color: var(--secondary-color);
    font-size: 1.1em;
    display: block;
    text-align: center;
    margin-top: 5px;
}

.control-group small {
    display: block;
    margin-top: 5px;
    color: var(--light-text);
    font-size: 0.85em;
}

.button-group {
    display: flex;
    gap: 10px;
    margin: 20px 0;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 4px;
    font-size: 1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    flex: 1;
}

.btn-primary {
    background: var(--success-color);
    color: white;
}

.btn-primary:hover {
    background: #218838;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(40, 167, 69, 0.3);
}

.btn-secondary {
    background: var(--secondary-color);
    color: white;
}

.btn-secondary:hover {
    background: #2589c7;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(47, 164, 231, 0.3);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.info-display {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
    padding: 15px;
    background: var(--light-bg);
    border-radius: 6px;
    border: 1px solid var(--border-color);
    margin-top: 15px;
}

.info-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 10px;
    background: white;
    border-radius: 4px;
}

.info-item .label {
    font-size: 0.85em;
    color: var(--light-text);
    margin-bottom: 5px;
}

.info-item .value {
    font-size: 1.4em;
    font-weight: 700;
    color: var(--secondary-color);
}

.info-panel {
    overflow-y: auto;
    max-height: none;
}

.info-section {
    margin-bottom: 30px;
}

.info-section h2 {
    color: var(--primary-color);
    font-size: 1.5em;
    margin-bottom: 15px;
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 8px;
    font-weight: 700;
}

.info-section h3 {
    font-size: 1.2em;
    margin: 20px 0 10px 0;
    color: var(--secondary-color);
    font-weight: 600;
}

.control-group small {
    display: block;
    margin-top: 5px;
    color: var(--light-text);
    font-size: 0.85em;
}

.info-section p {
    margin-bottom: 15px;
    text-align: justify;
}

.info-section ul,
.info-section ol {
    margin-left: 20px;
    margin-bottom: 15px;
}

.info-section li {
    margin-bottom: 12px;
}

.info-section strong {
    color: var(--secondary-color);
}

.equation {
    background: var(--light-bg);
    padding: 20px;
    margin: 20px 0;
    border-left: 4px solid var(--secondary-color);
    font-size: 1.1em;
    text-align: center;
    border-radius: 5px;
    overflow-x: auto;
}

.footnote {
    border-top: 2px solid var(--border-color);
    padding-top: 20px;
}

.footnote p {
    font-size: 0.9em;
    color: var(--light-text);
}

footer {
    text-align: center;
    color: var(--light-text);
    padding: 20px;
    margin-top: 30px;
    background-color: var(--background-color);
    border-top: 1px solid var(--border-color);
}

/* Visualization Toggles */
.visualization-toggles {
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 6px;
    margin-top: 10px;
}

.toggle-header {
    display: block;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 10px;
    font-size: 0.95em;
}

.checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    font-size: 0.9em;
    color: var(--dark-text);
}

.checkbox-label input[type="checkbox"] {
    cursor: pointer;
    width: 18px;
    height: 18px;
}

.checkbox-label:hover {
    color: var(--secondary-color);
}

/* Graphs Panel */
.graphs-panel {
    margin-top: 0;
    padding: 20px;
    background-color: var(--background-color);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 1100px;
    margin-left: auto;
    margin-right: auto;
}

.graphs-panel.hidden {
    display: none;
}

.graphs-panel h3 {
    margin-bottom: 15px;
    color: var(--primary-color);
    font-size: 1.2em;
    text-align: center;
}

.graphs-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.graph-box {
    background-color: white;
    padding: 15px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.graph-box canvas {
    display: block;
    width: 100%;
    height: auto;
    border: none;
    background: white;
}

.graph-label {
    text-align: center;
    margin-top: 10px;
    font-size: 0.9em;
    color: var(--dark-text);
    font-weight: 600;
}

/* Tab Navigation */
.tab-navigation {
    display: flex;
    gap: 0;
    border-bottom: 2px solid var(--border-color);
    margin-bottom: 0;
}

.tab-button {
  border-radius: 10px;
  background: linear-gradient(160deg, #0d839f, #0b5f77);
  color: #ffffff;
  font-weight: 700;
  border: 1px solid #0a5d74;
  padding: 0.58rem 0.82rem;
  cursor: pointer;
}

.tab-button:hover {
    background-color: #e9ecef;
    color: var(--dark-text);
}

.tab-button.active {
    background-color: var(--background-color);
    color: var(--secondary-color);
    border-bottom-color: var(--secondary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Exploration Section */
.exploration-section {
    background-color: #f0f8ff;
    border-left: 4px solid var(--secondary-color);
}

.exploration-intro {
    font-weight: 500;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.exploration-item {
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 12px;
    overflow: hidden;
}

.exploration-item summary {
    padding: 15px;
    cursor: pointer;
    font-weight: 600;
    color: var(--secondary-color);
    user-select: none;
    transition: background-color 0.2s;
}

.exploration-item summary:hover {
    background-color: #f8f9fa;
}

.exploration-item[open] summary {
    background-color: var(--secondary-color);
    color: white;
}

.exploration-content {
    padding: 15px;
    border-top: 1px solid var(--border-color);
}

.exploration-content p {
    margin-bottom: 10px;
}

.exploration-content strong {
    color: var(--primary-color);
}


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

/* Input Validation */
input:invalid {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px rgba(231, 76, 60, 0.1);
}

input:focus:invalid {
    outline-color: var(--accent-color);
}

.error-message {
    color: var(--accent-color);
    font-size: 0.85em;
    margin-top: 4px;
    display: none;
}

input:invalid + .error-message {
    display: block;
}

/* Responsive Design */
@media (max-width: 1200px) {
    .simulation-container {
        grid-template-columns: 1fr;
    }
    
    .controls {
        max-width: 600px;
        margin: 0 auto;
    }
}

@media (max-width: 900px) {
    #atwoodCanvas {
        width: 100%;
        height: auto;
        max-width: 600px;
    }
    
    .canvas-area {
        flex-direction: column;
        align-items: center;
    }
    
    .force-diagrams {
        flex-direction: row;
        justify-content: center;
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.8em;
    }
    
    .subtitle {
        font-size: 0.95em;
    }
    
    #atwoodCanvas {
        width: 100%;
        height: auto;
    }
    
    .info-display {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .graphs-container {
        grid-template-columns: 1fr;
    }
    
    .tab-button {
  border-radius: 10px;
  background: linear-gradient(160deg, #0d839f, #0b5f77);
  color: #ffffff;
  font-weight: 700;
  border: 1px solid #0a5d74;
  padding: 0.58rem 0.82rem;
  cursor: pointer;
}
    
    .simulation-panel {
        padding: 15px;
    }
}