/* CSS Variables for Dark/Light Theme */
:root {
    --bg-color: #f0f4f8;
    --container-bg: #ffffff;
    --text-color: #1a202c;
    --primary-color: #4a5568;
    --accent-color: #3b82f6;
    --accent-light: #60a5fa;
    --accent-dark: #2563eb;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --border-color: #e2e8f0;
    --sorted-color: #48bb78;
    --comparing-color: #f6ad55;
    --swapping-color: #f56565;
    --path-color: #a0aec0;
    --visited-color: #90cdf4;
}

[data-theme="dark"] {
    --bg-color: #1a202c;
    --container-bg: #2d3748;
    --text-color: #e2e8f0;
    --primary-color: #a0aec0;
    --accent-color: #63b3ed;
    --accent-light: #90cdf4;
    --accent-dark: #4299e1;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --border-color: #4a5568;
    --sorted-color: #68d391;
    --comparing-color: #f6e0b5;
    --swapping-color: #fc8181;
    --path-color: #718096;
    --visited-color: #4299e1;
}

/* General Styling */
body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    transition: background-color 0.3s ease, color 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 1200px;
    padding: 2rem;
    box-sizing: border-box;
}

header {
    width: 100%;
    background-color: var(--container-bg);
    box-shadow: 0 4px 6px var(--shadow-color);
    padding: 1rem 2rem;
    margin-bottom: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.header-title {
    display: flex;
    align-items: center;
    gap: 10px;
}

.header-title img {
    height: 35px;
}

header h1 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 700;
}

.nav-links {
    display: flex;
    gap: 1rem;
}

.nav-button {
    background: none;
    border: none;
    color: var(--primary-color);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    transition: all 0.2s ease-in-out;
}

.nav-button:hover {
    color: var(--accent-color);
    background-color: var(--border-color);
}

.nav-button.active {
    background-color: var(--accent-color);
    color: #ffffff;
    box-shadow: 0 4px 6px -1px var(--shadow-color), 0 2px 4px -1px var(--shadow-color);
}

.theme-toggle {
    cursor: pointer;
    font-size: 1.5rem;
    padding: 0.5rem;
    border-radius: 50%;
    transition: all 0.2s ease-in-out;
    color: var(--primary-color);
}

.theme-toggle:hover {
    background-color: var(--border-color);
    color: var(--accent-color);
}

main {
    width: 100%;
}

.section {
    display: none;
}

.section.active {
    display: block;
}

.visualizer-card {
    background-color: var(--container-bg);
    border-radius: 1rem;
    box-shadow: 0 10px 15px -3px var(--shadow-color), 0 4px 6px -2px var(--shadow-color);
    padding: 2rem;
    margin-bottom: 2rem;
}

.controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    align-items: center;
    margin-bottom: 1.5rem;
}

.control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    width: fit-content;
    position: relative;
}

label {
    font-size: 0.875rem;
    color: var(--primary-color);
}

select, button, input[type="range"] {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.5rem 1rem;
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

select:hover, button:hover {
    border-color: var(--accent-light);
}

button {
    font-weight: 600;
    background-image: linear-gradient(135deg, var(--accent-color), var(--accent-dark));
    color: #ffffff;
    border: none;
    box-shadow: 0 4px 6px -1px var(--shadow-color), 0 2px 4px -1px var(--shadow-color);
}

button.notes-btn {
    background-image: none;
    background-color: var(--primary-color);
}

button.notes-btn:hover {
    background-color: var(--accent-color);
}

button:hover {
    opacity: 0.9;
}

button:disabled {
    background-image: none;
    background-color: var(--border-color);
    color: var(--primary-color);
    cursor: not-allowed;
    box-shadow: none;
}

.stats {
    text-align: center;
    font-size: 0.875rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.user-input {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
    width: 100%;
    margin-bottom: 1rem;
}

.user-input input {
    width: 100%;
    max-width: 500px;
    text-align: center;
}

/* Sorting Visualizer specific styling */
.visualizer {
    display: flex;
    align-items: flex-end;
    gap: 2px;
    height: 400px;
    width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    padding: 0.5rem;
    box-sizing: border-box;
    background-color: var(--bg-color);
    overflow-x: auto;
    position: relative;
}

.bar-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
    position: relative;
    width: 100%;
    height: 100%;
}

.bar {
    background-color: var(--accent-color);
    width: 100%;
    transition: background-color 0.4s ease, transform 0.4s ease;
    border-radius: 2px 2px 0 0;
    position: relative;
}

.bar-value {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    margin-top: -1.2em;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-color);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    text-align: center;
    width: 100%;
}

.speed-tooltip {
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    padding: 0.25rem 0.5rem;
    background-color: var(--primary-color);
    color: white;
    border-radius: 0.25rem;
    font-size: 0.75rem;
    white-space: nowrap;
    opacity: 0;
    transition: opacity 0.2s ease;
    pointer-events: none;
}

.control-group:hover .speed-tooltip {
    opacity: 1;
}

.bar.comparing { background-color: var(--comparing-color); transition: background-color 0s ease; }
.bar.swapping { background-color: var(--swapping-color); transition: background-color 0s ease; }
.bar.sorted { background-color: var(--sorted-color); transition: background-color 0s ease; }
.bar.sorted:last-of-type { border-bottom: 2px solid var(--sorted-color); }

/* Pathfinding Visualizer specific styling */
.grid-container {
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: auto;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    height: 600px;
    width: 100%;
}

.grid {
    display: grid;
    border: 1px solid var(--border-color);
    background-color: var(--container-bg);
}

.node {
    width: 25px;
    height: 25px;
    background-color: var(--container-bg);
    border: 1px solid var(--border-color);
    transition: background-color 0.2s ease, transform 0.2s ease;
    box-sizing: border-box;
    cursor: pointer;
}

.node.wall { background-color: var(--primary-color); }
.node.start { background-color: var(--sorted-color); }
.node.end { background-color: var(--swapping-color); }
.node.visited { 
    background-color: var(--visited-color); 
    animation: visitedAnim 0.5s ease-in-out forwards;
}
.node.path { 
    background-color: var(--accent-color); 
    animation: pathAnim 0.5s ease-in-out forwards;
}

@keyframes visitedAnim {
    from { transform: scale(0.5); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}
@keyframes pathAnim {
    from { transform: scale(0.5); opacity: 0; }
    to { transform: scale(1.1); opacity: 1; }
}

/* Modal for notes */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.4);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.modal-content {
    background-color: var(--container-bg);
    margin: 15% auto;
    padding: 2rem;
    border-radius: 1rem;
    width: 80%;
    max-width: 600px;
    position: relative;
    box-shadow: 0 4-12px var(--shadow-color);
}

.close-button {
    color: var(--primary-color);
    position: absolute;
    top: 10px;
    right: 20px;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    transition: color 0.2s ease;
}

.close-button:hover,
.close-button:focus {
    color: var(--swapping-color);
}

.modal-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 1rem;
}

.modal-body {
    line-height: 1.6;
}

.modal-body strong {
    color: var(--accent-dark);
}

footer {
    width: 100%;
    text-align: center;
    padding: 1rem;
    margin-top: 2rem;
    background-color: var(--container-bg);
    box-shadow: 0 -4px 6px var(--shadow-color);
    color: var(--primary-color);
    font-size: 0.875rem;
    border-radius: 1rem 1rem 0 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }
    .controls {
        flex-direction: column;
        align-items: stretch;
    }
    .visualizer-card {
        padding: 1.5rem;
    }
}