/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    overflow: hidden;
    background-color: #2a2a2a;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
}

/* Canvas */
#chalkboard {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    cursor: none;
    background-color: #0a3d0a;
    background-image: 
        repeating-linear-gradient(
            0deg,
            transparent,
            transparent 2px,
            rgba(255, 255, 255, 0.03) 2px,
            rgba(255, 255, 255, 0.03) 4px
        ),
        repeating-linear-gradient(
            90deg,
            transparent,
            transparent 2px,
            rgba(255, 255, 255, 0.03) 2px,
            rgba(255, 255, 255, 0.03) 4px
        );
    /* Fallback for missing bg.png */
    background-size: 50px 50px;
}

/* Chalk cursor */
.chalk {
    width: 40px;
    height: 40px;
    position: absolute;
    padding: 0;
    margin: 0;
    cursor: none;
    z-index: 2;
    pointer-events: none;
    transform: translate(-50%, -50%);
    transition: transform 0.1s ease;
}

/* Chalk visual representation */
.chalk::before {
    content: '';
    display: block;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #ffffff 0%, #e0e0e0 50%, #ffffff 100%);
    border-radius: 50%;
    box-shadow: 
        0 0 5px rgba(255, 255, 255, 0.5),
        inset -2px -2px 4px rgba(0, 0, 0, 0.2);
    /* Fallback for missing chalk.png */
}

/* Eraser mode */
.chalk.eraser {
    width: 60px;
    height: 100px;
    transform: translate(-50%, -50%) rotate(5deg);
}

.chalk.eraser::before {
    background: linear-gradient(135deg, #8B7355 0%, #6B5D4F 50%, #8B7355 100%);
    border-radius: 5px;
    box-shadow: 
        inset 0 0 10px rgba(0, 0, 0, 0.3),
        0 2px 4px rgba(0, 0, 0, 0.2);
}

/* Control Panel */
.panel {
    position: fixed;
    bottom: 20px;
    left: 20px;
    z-index: 10;
    display: flex;
    gap: 10px;
    align-items: center;
    background: rgba(0, 0, 0, 0.7);
    padding: 12px 16px;
    border-radius: 8px;
    backdrop-filter: blur(10px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

/* Buttons */
.panel button {
    padding: 8px 16px;
    background: rgba(255, 255, 255, 0.9);
    color: #333;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    outline: none;
}

.panel button:hover {
    background: #ffffff;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(255, 255, 255, 0.3);
}

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

.panel button:focus-visible {
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.5);
}

/* Eraser button active state */
.btn-toggle-eraser.active {
    background: #ff6b6b;
    color: white;
}

/* Color picker */
.color-picker {
    position: relative;
    width: 40px;
    height: 40px;
    border-radius: 4px;
    overflow: hidden;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

#chalk-color {
    position: absolute;
    width: 200%;
    height: 200%;
    top: -50%;
    left: -50%;
    border: none;
    cursor: pointer;
    background: none;
}

/* GitHub Fork Banner */
.github-fork {
    position: fixed;
    top: 0;
    right: 0;
    z-index: 11;
    fill: #ffffff;
    color: #0a3d0a;
}

.github-fork:hover .octo-arm {
    animation: octocat-wave 560ms ease-in-out;
}

@keyframes octocat-wave {
    0%, 100% { transform: rotate(0); }
    20%, 60% { transform: rotate(-25deg); }
    40%, 80% { transform: rotate(10deg); }
}

/* Help Tooltip */
.help-tooltip {
    position: fixed;
    top: 20px;
    left: 20px;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 15px;
    border-radius: 8px;
    font-size: 13px;
    line-height: 1.5;
    z-index: 10;
    max-width: 250px;
    backdrop-filter: blur(10px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.help-tooltip.show {
    opacity: 1;
}

.help-tooltip p {
    margin: 5px 0;
}

.help-tooltip strong {
    color: #4CAF50;
}

/* Download link */
.download-link {
    padding: 8px 16px;
    background: #4CAF50;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.2s ease;
    display: inline-block;
}

.download-link:hover {
    background: #45a049;
    transform: translateY(-1px);
}

/* Loading indicator */
.loading {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 18px;
    z-index: 100;
    padding: 20px;
    background: rgba(0, 0, 0, 0.8);
    border-radius: 8px;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .panel {
        bottom: 10px;
        left: 10px;
        padding: 8px 12px;
        flex-wrap: wrap;
    }
    
    .panel button {
        font-size: 12px;
        padding: 6px 12px;
    }
    
    .help-tooltip {
        display: none;
    }
    
    .github-fork {
        width: 60px;
        height: 60px;
    }
}

@media (hover: none) {
    /* Touch device optimizations */
    .panel {
        bottom: 0;
        left: 0;
        right: 0;
        border-radius: 0;
        justify-content: space-around;
    }
    
    .chalk {
        display: none;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .panel {
        background: black;
        border: 2px solid white;
    }
    
    .panel button {
        border: 1px solid white;
    }
}