:root {
     --primary-color: #2563eb;
     --primary-hover: #1d4ed8;
     --secondary-color: #64748b;
     --success-color: #059669;
     --warning-color: #d97706;
     --background: #f8fafc;
     --surface: #ffffff;
     --border: #e2e8f0;
     --text: #1e293b;
     --text-muted: #64748b;
     --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
     --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
     --radius: 0.5rem;
     --radius-lg: 0.75rem;
     --accent-color: #8B4B62;
 }

 * {
     box-sizing: border-box;
 }

 body {
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
     line-height: 1.6;
     color: var(--text);
     background: var(--background);
     margin: 0;
     padding: 0;
 }

 .container {
     max-width: 1200px;
     margin: 0 auto;
     padding: 1rem;
 }

 .header {
     text-align: center;
     margin-bottom: 3rem;
     padding: 2rem 0;
 }

 h1 {
     font-size: clamp(1.75rem, 4vw, 2.5rem);
     font-weight: 700;
     color: var(--text);
     margin: 0 0 1rem 0;
     background: linear-gradient(45deg, var(--primary-color), var(--success-color));
     -webkit-background-clip: text;
     -webkit-text-fill-color: transparent;
     background-clip: text;
 }

 .intro {
     max-width: 800px;
     margin: 0 auto;
     font-size: 1.1rem;
     color: var(--text-muted);
     line-height: 1.7;
 }

 .intro p {
     margin-bottom: 1rem;
 }

 .card {
     background: var(--surface);
     border-radius: var(--radius-lg);
     box-shadow: var(--shadow);
     border: 1px solid var(--border);
     margin-bottom: 2rem;
     overflow: hidden;
 }

 .card-header {
     padding: 1.5rem;
     border-bottom: 1px solid var(--border);
     background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
 }

 .card-title {
     font-size: 1.25rem;
     font-weight: 600;
     color: var(--text);
     margin: 0;
     display: flex;
     align-items: center;
     gap: 0.5rem;
 }

 .card-content {
     padding: 1.5rem;
 }

 .parameter-grid {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
     gap: 1.5rem;
     margin-bottom: 2rem;
 }

 .parameter-field {
     display: flex;
     flex-direction: column;
     gap: 0.5rem;
 }

 .parameter-field label {
     font-weight: 600;
     color: var(--text);
     font-size: 0.875rem;
     text-transform: uppercase;
     letter-spacing: 0.05em;
 }

 .slider-container {
     display: flex;
     align-items: center;
     gap: 1rem;
     background: var(--background);
     padding: 0.75rem;
     border-radius: var(--radius);
     border: 1px solid var(--border);
 }

 .slider-container input[type="range"] {
     flex: 1;
     height: 6px;
     border-radius: 3px;
     background: #e2e8f0;
     outline: none;
     -webkit-appearance: none;
 }

 .slider-container input[type="range"]::-webkit-slider-thumb {
     -webkit-appearance: none;
     appearance: none;
     width: 20px;
     height: 20px;
     border-radius: 50%;
     background: var(--primary-color);
     cursor: pointer;
     box-shadow: var(--shadow);
     transition: all 0.2s;
 }

 .slider-container input[type="range"]::-webkit-slider-thumb:hover {
     background: var(--primary-hover);
     transform: scale(1.1);
 }

 .slider-container input[type="range"]::-moz-range-thumb {
     width: 20px;
     height: 20px;
     border-radius: 50%;
     background: var(--primary-color);
     cursor: pointer;
     border: none;
     box-shadow: var(--shadow);
 }

 .value-display {
     min-width: 60px;
     text-align: center;
     font-weight: 600;
     color: var(--primary-color);
     background: var(--surface);
     padding: 0.25rem 0.75rem;
     border-radius: var(--radius);
     border: 1px solid var(--border);
     font-size: 0.875rem;
 }

 .simulation-controls {
     display: flex;
     flex-direction: column;
     align-items: center;
     gap: 1rem;
     margin: 2rem 0;
 }

 .button-group {
     display: flex;
     gap: 1rem;
     align-items: center;
 }

 #status {
     padding: 1rem 1.5rem;
     background: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
     color: var(--primary-color);
     border-radius: var(--radius);
     border: 1px solid #93c5fd;
     font-weight: 500;
     text-align: center;
     min-width: 300px;
 }

 #run-btn,
 #pause-btn {
     background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
     color: white;
     padding: 1rem 2rem;
     border: none;
     border-radius: var(--radius);
     font-size: 1.1rem;
     font-weight: 600;
     cursor: pointer;
     transition: all 0.3s ease;
     box-shadow: var(--shadow);
     min-width: 200px;
     position: relative;
     overflow: hidden;
 }

 #pause-btn {
     background: linear-gradient(135deg, var(--warning-color), #b45309);
     min-width: 150px;
 }

 #run-btn:hover:not(:disabled),
 #pause-btn:hover:not(:disabled) {
     transform: translateY(-2px);
     box-shadow: var(--shadow-lg);
 }

 #run-btn:disabled {
     background: var(--secondary-color);
     cursor: not-allowed;
     transform: none;
 }

 #pause-btn:disabled {
     background: var(--secondary-color);
     cursor: not-allowed;
     transform: none;
 }

 #run-btn::before,
 #pause-btn::before {
     content: '';
     position: absolute;
     top: 0;
     left: -100%;
     width: 100%;
     height: 100%;
     background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
     transition: left 0.5s;
 }

 #run-btn:hover::before,
 #pause-btn:hover::before {
     left: 100%;
 }

 .plots-container {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
     gap: 2rem;
     margin-top: 2rem;
 }

 .plot-card {
     background: var(--surface);
     border-radius: var(--radius-lg);
     box-shadow: var(--shadow);
     border: 1px solid var(--border);
     overflow: hidden;
 }

 .plot-header {
     padding: 1rem 1.5rem;
     background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
     border-bottom: 1px solid var(--border);
 }

 .plot-title {
     font-size: 1.1rem;
     font-weight: 600;
     color: var(--text);
     margin: 0;
 }

 .plot-content {
     padding: 1rem;
     display: flex;
     justify-content: center;
     align-items: center;
     min-height: 700px;
     background: #fafafa;
 }

 details {
     background: var(--surface);
     border: 1px solid var(--border);
     border-radius: var(--radius-lg);
     margin: 2rem 0;
     box-shadow: var(--shadow);
 }

 summary {
     padding: 1.5rem;
     font-weight: 600;
     cursor: pointer;
     background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
     border-radius: var(--radius-lg);
     transition: all 0.2s;
     user-select: none;
 }

 summary:hover {
     background: linear-gradient(135deg, #f1f5f9 0%, #e2e8f0 100%);
 }

 details[open] summary {
     border-bottom: 1px solid var(--border);
     border-radius: var(--radius-lg) var(--radius-lg) 0 0;
     margin-bottom: 0;
 }

 .details-content {
     padding: 1.5rem;
 }

 .details-content h2 {
     color: var(--text);
     margin-top: 0;
     margin-bottom: 1rem;
     font-size: 1.25rem;
 }

 .details-content p {
     margin-bottom: 1rem;
     line-height: 1.7;
 }

 .details-content a {
     color: var(--primary-color);
     text-decoration: none;
     font-weight: 500;
 }

 .details-content a:hover {
     text-decoration: underline;
 }

 .emoji {
     font-size: 1.2em;
     margin-right: 0.5rem;
 }

 @media (max-width: 768px) {
     .container {
         padding: 0.5rem;
     }

     .parameter-grid {
         grid-template-columns: 1fr;
         gap: 1rem;
     }

     .plots-container {
         grid-template-columns: 1fr;
         gap: 1rem;
     }

     .plot-content {
         min-height: 400px;
     }

     .slider-container {
         padding: 0.5rem;
     }

     .card-content {
         padding: 1rem;
     }

     h1 {
         font-size: 1.75rem;
     }

     .intro {
         font-size: 1rem;
     }
 }

 @media (max-width: 480px) {
     .parameter-grid {
         gap: 0.75rem;
     }

     .slider-container {
         flex-direction: column;
         align-items: stretch;
         gap: 0.5rem;
     }

     .value-display {
         align-self: center;
         min-width: auto;
     }

     #run-btn {
         width: 100%;
         max-width: 300px;
     }

     #pause-btn {
         width: 100%;
         max-width: 200px;
     }

     .button-group {
         flex-direction: column;
         width: 100%;
         max-width: 300px;
     }
 }

 /* Loading animation */
 .loading {
     display: inline-block;
     width: 20px;
     height: 20px;
     border: 3px solid rgba(255, 255, 255, .3);
     border-radius: 50%;
     border-top-color: #fff;
     animation: spin 1s ease-in-out infinite;
     margin-right: 0.5rem;
 }

 @keyframes spin {
     to {
         transform: rotate(360deg);
     }
 }

 /* Responsive plots */
 #temperature_plot,
 #doc_plot {
     width: 100% !important;
     height: 700px !important;
 }

 @media (max-width: 768px) {

     #temperature_plot,
     #doc_plot {
         height: 700px !important;
     }
 }

 .topnav {
     color: var(--accent-color);
     text-align: center;
     padding: 1rem 0;
     margin-bottom: 2rem;
 }

 .topnav a {
     color: var(--accent-color);
     margin: 0 10px;
     text-decoration: none;
     cursor: pointer;
 }

 .topnav a:hover {
     text-decoration: underline;
 }

 .topnav a:link {
     color: var(--accent-color);
 }

 .topnav a:visited {
     color: var(--accent-color);
 }

 .topnav a:first-child {
     margin-left: 0;
     /* Remove the left margin for the first link */
 }