:root {
    --primary-color: #4a6fa5;
    --secondary-color: #166088;
    --accent-color: #4fc3f7;
    --dark-color: #333;
    --light-color: #f8f9fa;
    --danger-color: #dc3545;
    --success-color: #28a745;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #e9ecef;
    color: var(--dark-color);
    line-height: 1.6;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    max-width: 100vw;
    background-color: white;
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.app-actions {
    display: flex;
    gap: 0.5rem;
}

button {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    background-color: var(--secondary-color);
    color: white;
    cursor: pointer;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

button:hover {
    background-color: var(--accent-color);
    transform: translateY(-1px);
}

button:active {
    transform: translateY(0);
}

.main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.toolbar {
    width: 250px;
    background-color: var(--light-color);
    padding: 1rem;
    overflow-y: auto;
    border-right: 1px solid #ddd;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.tool-section {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.tool-section h3 {
    font-size: 1rem;
    color: var(--secondary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid #ddd;
}

.tool-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
}

.tool-btn {
    aspect-ratio: 1;
    padding: 0.5rem;
    font-size: 1.2rem;
    background-color: white;
    color: var(--dark-color);
    border: 1px solid #ddd;
}

.tool-btn.active {
    background-color: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
}

.color-pickers {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.color-presets {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.preset {
    aspect-ratio: 1;
    border-radius: 4px;
    cursor: pointer;
    border: 1px solid #ddd;
    transition: transform 0.1s;
}

.preset:hover {
    transform: scale(1.1);
}

.setting {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

input[type="range"] {
    width: 100%;
}

.history-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.canvas-container {
    flex: 1;
    position: relative;
    overflow: auto;
    background-color: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
}

#drawing-canvas {
    background-color: white;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    cursor: crosshair;
    touch-action: none;
}

.canvas-actions {
    position: absolute;
    bottom: 1rem;
    right: 1rem;
    display: flex;
    gap: 0.5rem;
}

.status-bar {
    padding: 0.5rem 1rem;
    background-color: var(--dark-color);
    color: white;
    font-size: 0.8rem;
    display: flex;
    justify-content: space-between;
}

dialog {
    border: none;
    border-radius: 8px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.2);
    width: 90%;
    max-width: 400px;
    padding: 1.5rem;
}

dialog h2 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.dialog-content {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.dialog-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 0.5rem;
    margin-top: 1rem;
}

#cancel-save, #cancel-load {
    background-color: #6c757d;
}

#confirm-save, #confirm-load {
    background-color: var(--success-color);
}

.format-options {
    display: flex;
    gap: 1rem;
}

input[type="text"], input[type="file"] {
    padding: 0.5rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    width: 100%;
}

@media (max-width: 768px) {
    .main-content {
        flex-direction: column;
    }
    
    .toolbar {
        width: 100%;
        flex-direction: row;
        flex-wrap: wrap;
        border-right: none;
        border-bottom: 1px solid #ddd;
    }
    
    .tool-section {
        flex: 1;
        min-width: 150px;
    }
}