/**
 * Canvas Layering, Blend Modes, and Floating Zoom HUD
 * Layer 0: Paper texture
 * Layer 1: Color paint
 * Layer 2: Pencil line-art with 'multiply' blend mode
 * Layer 3: Interactive touch/pen overlay
 * Floating HUD: Part Focus & Zoom Controls
 */

.canvas-viewport {
    width: 100%;
    height: 100%;
    position: relative;
    overflow: hidden;
    touch-action: none; /* Prevents browser default scrolling while drawing */
    user-select: none;
    -webkit-user-select: none;
    background: #0E0F14;
    cursor: crosshair;
}

.canvas-layers-stack {
    position: absolute;
    top: 0;
    left: 0;
    transform-origin: 0 0;
    will-change: transform;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.7);
}

.canvas-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    image-rendering: auto;
}

/* Base Sketch Paper Background Layer */
#layer-bg {
    z-index: 1;
}

/* User Color Layer (Brushes & Fills render underneath the pencil lines) */
#layer-color {
    z-index: 2;
}

/* Pencil Line-Art Sketch Layer (Always on top with Multiply blend mode) */
#layer-sketch {
    z-index: 3;
    mix-blend-mode: multiply;
}

/* Active Touch & Pointer Overlay Layer */
#layer-overlay {
    z-index: 4;
    pointer-events: auto; /* Receives all mouse, touch, and pen pointerdown/up events */
}

/* Floating Zoom & Focus Navigation HUD */
.canvas-zoom-hud {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(22, 24, 32, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 9999px;
    padding: 6px 14px;
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 30;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.6);
    user-select: none;
    pointer-events: auto;
    transition: all 0.2s ease;
}

.canvas-zoom-hud:hover {
    border-color: rgba(255, 71, 87, 0.4);
    box-shadow: 0 10px 36px rgba(0, 0, 0, 0.7);
}

.hud-group {
    display: flex;
    align-items: center;
    gap: 6px;
}

.hud-label {
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--accent-gold, #FFA502);
    text-transform: uppercase;
    letter-spacing: 0.4px;
    margin-right: 2px;
}

.hud-chip {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: #FFFFFF;
    border-radius: 9999px;
    padding: 4px 10px;
    font-size: 0.75rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}

.hud-chip:hover {
    background: rgba(255, 71, 87, 0.25);
    border-color: var(--accent-primary, #FF4757);
    transform: translateY(-1px);
}

.hud-divider {
    width: 1px;
    height: 18px;
    background: rgba(255, 255, 255, 0.15);
}

.hud-tool-btn {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: #FFFFFF;
    border-radius: 6px;
    padding: 3px 8px;
    font-size: 0.82rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.12s ease;
}

.hud-tool-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #FFFFFF;
}

.hud-fit-btn {
    background: rgba(30, 144, 255, 0.25);
    border: 1px solid rgba(30, 144, 255, 0.6);
    color: #82B1FF;
    font-weight: 700;
    padding: 5px 12px;
    border-radius: 9999px;
    box-shadow: 0 0 10px rgba(30, 144, 255, 0.3);
}

.hud-fit-btn:hover {
    background: rgba(30, 144, 255, 0.5);
    border-color: #82B1FF;
    color: #FFFFFF;
    box-shadow: 0 0 16px rgba(30, 144, 255, 0.6);
    transform: translateY(-1px);
}

.hud-zoom-level {
    font-size: 0.76rem;
    font-weight: 700;
    font-family: monospace;
    color: #FFFFFF;
    min-width: 42px;
    text-align: center;
}

/* Mobile Responsiveness for HUD */
@media (max-width: 600px) {
    .canvas-zoom-hud {
        bottom: 12px;
        padding: 4px 10px;
        gap: 6px;
        max-width: 95%;
        overflow-x: auto;
    }

    .hud-label {
        display: none;
    }

    .hud-chip {
        padding: 3px 8px;
        font-size: 0.7rem;
    }
}