/* --- Global Styles & Variables --- */
:root {
    --bg-primary: #1a1a2e;
    --bg-secondary: #16213e;
    --accent-color: #e94560;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0c0;
    --border-color: #2a3a5e;
    --success-color: #50fa7b;
    --error-color: #ff5555;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 1rem;
}

/* --- Main App Container --- */
.app-container {
    width: 100%;
    max-width: 600px;
    background-color: var(--bg-secondary);
    border-radius: 20px;
    box-shadow: 0 15px 50px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

header {
    padding: 1.5rem 2rem;
    background-color: rgba(0, 0, 0, 0.2);
    border-bottom: 1px solid var(--border-color);
    text-align: center;
}

header h1 {
    font-size: 1.75rem;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

main {
    padding: 2rem;
}

/* --- Section Management --- */
.app-section {
    display: none;
}

.app-section.active {
    display: block;
}

/* --- Upload Section --- */
#uploadArea {
    border: 3px dashed var(--border-color);
    border-radius: 15px;
    padding: 3rem 1.5rem;
    text-align: center;
    cursor: pointer;
    transition: background-color 0.3s, border-color 0.3s;
}

#uploadArea:hover,
#uploadArea.drag-over {
    background-color: rgba(233, 69, 96, 0.1);
    border-color: var(--accent-color);
}

#uploadArea .upload-icon {
    font-size: 3rem;
    color: var(--accent-color);
    margin-bottom: 1rem;
}

#uploadArea h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

#uploadArea p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

#fileInput {
    display: none;
}

/* --- Editor Section --- */
.canvas-container {
    width: 100%;
    max-width: 500px;
    margin: 0 auto 2rem;
    cursor: move;
    touch-action: none;
}

.canvas-container canvas {
    display: block;
    width: 100%;
    height: auto;
}

.controls-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.75rem;
}

.control-group {
    display: flex;
    flex-direction: column;
}

.control-group label {
    margin-bottom: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Slider Styles */
.slider-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 5px;
    outline: none;
    opacity: 0.9;
    transition: opacity 0.2s;
}

input[type="range"]:hover {
    opacity: 1;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 22px;
    height: 22px;
    background: var(--accent-color);
    cursor: pointer;
    border-radius: 50%;
    border: 3px solid var(--bg-secondary);
}

input[type="range"]::-moz-range-thumb {
    width: 22px;
    height: 22px;
    background: var(--accent-color);
    cursor: pointer;
    border-radius: 50%;
    border: 3px solid var(--bg-secondary);
}

#dividerValue {
    font-weight: 600;
    color: var(--text-primary);
    min-width: 40px;
    text-align: right;
}

/* Color Picker Styles */
.color-picker-wrapper {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}

.color-picker-wrapper input[type="color"] {
    width: 60px;
    height: 45px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    background: none;
    padding: 0;
}

.color-picker-wrapper input[type="color"]::-webkit-color-swatch-wrapper {
    padding: 4px;
}

.color-picker-wrapper input[type="color"]::-webkit-color-swatch {
    border: none;
    border-radius: 4px;
}

.color-picker-wrapper input[type="text"] {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    text-transform: uppercase;
}

.color-picker-wrapper input[type="text"]:focus {
    outline: none;
    border-color: var(--accent-color);
}

/* --- Action Buttons --- */
.action-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
}

.btn {
    padding: 0.8rem 1rem;
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
    text-align: center;
}

.btn:hover {
    transform: translateY(-2px);
}

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

.btn-secondary {
    background-color: var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background-color: #3a4a6e;
}

#undoBgBtn {
    display: none;
}

.final-actions {
    margin-top: 2rem;
    width: 100%;
}

.final-actions .btn {
    width: 100%;
}

/* --- Loading Overlay --- */
#loadingOverlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    color: white;
    text-align: center;
}

#loadingOverlay.active {
    display: flex;
}

.spinner {
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top: 4px solid var(--accent-color);
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* --- Footer --- */
footer {
    text-align: center;
    padding: 1.5rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
}

footer a:hover {
    text-decoration: underline;
}

/* --- Mobile Responsiveness --- */
@media (max-width: 768px) {
    body {
        padding: 0.5rem;
    }
    
    .app-container {
        border-radius: 0;
        min-height: 100vh;
    }

    main {
        padding: 1.5rem;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .canvas-container {
        max-width: 90vw;
    }

    .final-actions, .action-buttons {
        grid-template-columns: 1fr;
    }
}