:root {
    --bg-color: #0f172a;
    --panel-bg: rgba(30, 41, 59, 0.7);
    --accent-primary: #38bdf8;
    --accent-secondary: #818cf8;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --glass-border: rgba(255, 255, 255, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --canvas-bg: #1e293b;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body.light-theme {
    --bg-color: #f1f5f9;
    --panel-bg: rgba(255, 255, 255, 0.8);
    --accent-primary: #0ea5e9;
    --accent-secondary: #6366f1;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --glass-border: rgba(0, 0, 0, 0.05);
    --canvas-bg: #e2e8f0;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s ease;
}

/* Header */
header {
    padding: 0.75rem 1.5rem;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 100;
}

h1 {
    font-size: 1.25rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.025em;
}

.active-status {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    padding: 0.25rem 1rem;
    border-radius: 2rem;
    gap: 1rem;
}

.status-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.status-label {
    font-size: 0.65rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
}

.status-icon {
    display: flex;
    align-items: center;
    color: var(--accent-primary);
}

.status-icon svg {
    width: 16px;
    height: 16px;
}

.status-divider {
    width: 1px;
    height: 16px;
    background: var(--glass-border);
}

.color-preview {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid white;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.3);
}

/* Header Color UI */
.header-center {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    padding: 0.4rem 1.2rem;
    border-radius: 3rem;
    gap: 1.25rem;
    flex: 0 1 auto;
}

.header-palette {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.header-divider {
    width: 1px;
    height: 20px;
    background: var(--glass-border);
}

.custom-color-trigger {
    position: relative;
    display: flex;
    align-items: center;
    cursor: pointer;
}

.custom-color-trigger input[type="color"] {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

.header-palette .color-swatch {
    width: 24px;
    height: 24px;
}

.header-palette.recent .color-swatch {
    width: 20px;
    height: 20px;
    opacity: 0.8;
}

.header-palette.recent .color-swatch:hover {
    opacity: 1;
}

/* Main Layout */
main {
    flex: 1;
    display: flex;
    position: relative;
    overflow: hidden;
}

/* Sidebar / Toolbar */
.toolbar {
    width: 280px;
    background: var(--panel-bg);
    backdrop-filter: blur(16px);
    border-right: 1px solid var(--glass-border);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    z-index: 50;
    overflow-y: auto;
    transition: var(--transition);
    position: relative;
}

.toolbar.collapsed {
    width: 0;
    padding: 0;
    margin: 0;
    border: none;
}

.sidebar-toggle {
    position: fixed; /* Use fixed to avoid clipping by toolbar width */
    top: 50%;
    left: 280px; /* Match sidebar width */
    transform: translateY(-50%);
    width: 32px;
    height: 64px;
    background: var(--accent-primary);
    border: none;
    border-radius: 0 8px 8px 0;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 4px 0 10px rgba(0, 0, 0, 0.3);
    z-index: 200;
    transition: var(--transition);
}

.toolbar.collapsed + .sidebar-toggle, 
.toolbar.collapsed .sidebar-toggle {
    left: 0;
}

.sidebar-toggle:hover {
    background: var(--accent-secondary);
    width: 40px;
}

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

.tool-section h3 {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.button-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
}

.tool-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 0.75rem;
    border-radius: 0.75rem;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.tool-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

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

.tool-btn i {
    font-size: 1.25rem;
}

/* Controls */
.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

input[type="range"] {
    width: 100%;
    accent-color: var(--accent-primary);
}

.color-picker-wrapper {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.color-swatch {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    cursor: pointer;
    border: 1px solid rgba(209, 213, 219, 0.5); /* Light grey border */
    transition: transform 0.1s, border-color 0.2s;
}

.color-swatch:hover {
    transform: scale(1.1);
    border-color: rgba(255, 255, 255, 0.8);
}

.color-swatch.active {
    border: 2px solid white;
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.3);
}

/* Canvas Area */
.canvas-container {
    flex: 1;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    background-image: 
        linear-gradient(45deg, var(--canvas-bg) 25%, transparent 25%), 
        linear-gradient(-45deg, var(--canvas-bg) 25%, transparent 25%), 
        linear-gradient(45deg, transparent 75%, var(--canvas-bg) 75%), 
        linear-gradient(-45deg, transparent 75%, var(--canvas-bg) 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
    overflow: hidden;
}

.canvas-wrapper {
    position: relative;
    max-width: 90%;
    max-height: 90%;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    background: white;
    overflow: hidden;
    cursor: crosshair;
    touch-action: none;
    user-select: none;
    -webkit-user-drag: none;
    transition: transform 0.1s ease-out;
}

.canvas-wrapper.cursor-pen {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="black" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M12 19l7-7 3 3-7 7-3-3z"></path><path d="M18 13l-1.5-7.5L2 2l3.5 14.5L13 18l5-5z"></path><path d="M2 2l5 5"></path><circle cx="11" cy="11" r="2"></circle></svg>') 2 2, auto;
}

.canvas-wrapper.cursor-fill {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="black" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M14 2l1.23 2.1a1 1 0 0 0 1.2.4l2.12-.7a1 1 0 0 1 1.25 1.25l-.7 2.12a1 1 0 0 0 .4 1.2L21.6 9.6a1 1 0 0 1 0 1.74l-2.1 1.23a1 1 0 0 0-.4 1.2l.7 2.12a1 1 0 0 1-1.25 1.25l-2.12-.7a1 1 0 0 0-1.2.4L14 21.6a1 1 0 0 1-1.74 0l-1.23-2.1a1 1 0 0 0-1.2-.4l-2.12.7a1 1 0 0 1-1.25-1.25l.7-2.12a1 1 0 0 0-.4-1.2L2.4 14.4a1 1 0 0 1 0-1.74l2.1-1.23a1 1 0 0 0 .4-1.2l-.7-2.12a1 1 0 0 1 1.25-1.25l2.12.7a1 1 0 0 0 1.2-.4L10 2.4a1 1 0 0 1 1.74 0z"></path></svg>') 12 12, auto;
}

canvas {
    display: block;
    user-select: none;
    -webkit-user-drag: none;
}

#colorCanvas {
    position: absolute;
    top: 0;
    left: 0;
}

#lineCanvas {
    position: relative;
    top: 0;
    left: 0;
    pointer-events: none;
    mix-blend-mode: multiply; /* Ensures lines blend nicely if needed, though we use transparency */
}

/* Upload Overlay */
.upload-overlay {
    position: absolute;
    inset: 0;
    background: rgba(15, 23, 42, 0.8);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 10;
    transition: opacity 0.3s ease;
}

.upload-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.upload-card {
    background: var(--panel-bg);
    border: 2px dashed var(--glass-border);
    padding: 3rem;
    border-radius: 1.5rem;
    text-align: center;
    max-width: 400px;
}

.upload-card i {
    font-size: 3rem;
    color: var(--accent-primary);
    margin-bottom: 1.5rem;
}

.upload-btn {
    background: var(--accent-primary);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 0.75rem;
    border: none;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1.5rem;
    transition: filter 0.2s;
}

.upload-btn:hover {
    filter: brightness(1.1);
}

/* Actions Footer */
.actions {
    display: flex;
    gap: 0.75rem;
    margin-top: auto;
}

.action-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 0.75rem;
    border: 1px solid var(--glass-border);
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s;
}

.action-btn.primary {
    background: var(--accent-primary);
    border: none;
}

.action-btn:hover {
    background: rgba(255, 255, 255, 0.1);
}

.action-btn.primary:hover {
    filter: brightness(1.1);
}

/* Custom Cursor for Tools */
.cursor-pen {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="black" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M12 19l7-7 3 3-7 7-3-3z"></path><path d="M18 13l-1.5-7.5L2 2l3.5 14.5L13 18l5-5z"></path><path d="M2 2l5 5"></path><circle cx="11" cy="11" r="2"></circle></svg>') 0 24, auto;
}

.cursor-fill {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="black" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M14 2l1.23 2.1a1 1 0 0 0 1.2.4l2.12-.7a1 1 0 0 1 1.25 1.25l-.7 2.12a1 1 0 0 0 .4 1.2L21.6 9.6a1 1 0 0 1 0 1.74l-2.1 1.23a1 1 0 0 0-.4 1.2l.7 2.12a1 1 0 0 1-1.25 1.25l-2.12-.7a1 1 0 0 0-1.2.4L14 21.6a1 1 0 0 1-1.74 0l-1.23-2.1a1 1 0 0 0-1.2-.4l-2.12.7a1 1 0 0 1-1.25-1.25l.7-2.12a1 1 0 0 0-.4-1.2L2.4 14.4a1 1 0 0 1 0-1.74l2.1-1.23a1 1 0 0 0 .4-1.2l-.7-2.12a1 1 0 0 1 1.25-1.25l2.12.7a1 1 0 0 0 1.2-.4L10 2.4a1 1 0 0 1 1.74 0z"></path></svg>') 12 12, auto;
}

/* Floating Zoom Controls */
.canvas-controls {
    position: absolute;
    bottom: 2rem;
    right: 2rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    z-index: 150;
}

.control-btn {
    width: 44px;
    height: 44px;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
    transition: var(--transition);
}

.control-btn:hover {
    background: var(--accent-primary);
    color: white;
    transform: scale(1.1);
}

.control-btn i {
    width: 20px;
    height: 20px;
}

.zoom-indicator {
    position: absolute;
    bottom: 2rem;
    left: 2rem;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    border: 1px solid var(--glass-border);
    z-index: 150;
    pointer-events: none;
}