* { box-sizing: border-box; }
body {
    margin: 0;
    padding: 0;
    display: flex;
    height: 100vh;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: #f5f5f5;
    overflow: hidden;
    transition: background-color 0.3s ease;
}

:root {
    --bg-color: #f5f5f5;
    --toolbar-bg: #ffffff;
    --toolbar-border: #e0e0e0;
    --btn-bg: #f8f9fa;
    --btn-text: #495057;
    --btn-active-bg: #e3f2fd;
    --btn-active-text: #0d47a1;
    --btn-active-border: #2196f3;
    --action-bg: #f1f3f5;
    --action-border: #dee2e6;
    --canvas-bg: #ffffff;
}

body.dark-theme {
    --bg-color: #121212;
    --toolbar-bg: #1e1e1e;
    --toolbar-border: #333333;
    --btn-bg: #2d2d2d;
    --btn-text: #e0e0e0;
    --btn-active-bg: #1565c0;
    --btn-active-text: #ffffff;
    --btn-active-border: #0d47a1;
    --action-bg: #333333;
    --action-border: #444444;
    --canvas-bg: #121212;
}

/* Barra de herramientas ultra compacta */
.toolbar {
    width: 80px; 
    background: var(--toolbar-bg);
    border-right: 1px solid var(--toolbar-border);
    padding: 8px 4px; /* Menos espacio arriba y abajo */
    display: flex;
    flex-direction: column;
    gap: 6px; /* Espacio mínimo entre botones */
    box-shadow: 2px 0 10px rgba(0,0,0,0.03);
    z-index: 10;
    transition: all 0.3s ease;
    overflow-y: auto; /* Permite deslizar la barra si falta espacio */
}
.toolbar::-webkit-scrollbar { display: none; }

.tool-btn {
    background: var(--btn-bg);
    border: 2px solid transparent;
    border-radius: 8px; /* Más cuadrados para ahorrar espacio */
    padding: 8px 0; 
    text-align: center;
    cursor: pointer;
    font-size: 10px; /* Texto más pequeño */
    font-weight: 600;
    color: var(--btn-text);
    transition: all 0.15s ease;
    user-select: none;
}

.tool-btn:active { transform: scale(0.95); }

.tool-btn.active {
    background: var(--btn-active-bg);
    border-color: var(--btn-active-border);
    color: var(--btn-active-text);
}

body:not(.dark-theme) .tool-btn[data-tool="select"] { background: #fff3e0; color: #e65100; border-color: #ffe0b2; }
body:not(.dark-theme) .tool-btn[data-tool="select"].active { background: #ffe0b2; border-color: #ff9800; }
body.dark-theme .tool-btn[data-tool="select"].active { background: #e65100; color: #fff; border-color: #ff9800; }

.action-btn {
    background: var(--action-bg);
    border: 2px solid var(--action-border);
    border-radius: 8px;
    padding: 6px 0; 
    font-size: 10px;
    font-weight: bold;
    cursor: pointer;
    text-align: center;
    color: var(--btn-text);
    user-select: none;
    transition: all 0.15s ease;
}
.action-btn:active { transform: scale(0.95); }

.zoom-container {
    display: flex;
    gap: 4px;
}
.zoom-btn {
    flex: 1;
    font-size: 14px;
    padding: 4px 0;
}

body:not(.dark-theme) .clear-btn { background: #ffebee; color: #c62828; border-color: #ffcdd2; }
body.dark-theme .clear-btn { background: #4a0000; color: #ff5252; border-color: #6a0000; }

.canvas-container {
    flex-grow: 1;
    position: relative;
    background-color: var(--canvas-bg);
    transition: background-color 0.3s ease;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
    touch-action: none; 
    cursor: crosshair;
}