:root {
    --primary-color: #4a6bff;
    --secondary-color: #f8f9fa;
    --text-color: #333;
    --light-text: #666;
    --border-color: #ddd;
    --error-color: #ff4a4a;
    --success-color: #2ecc71;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: #f5f7ff;
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    padding: 40px 0;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

header p {
    color: var(--light-text);
    font-size: 1.1rem;
}

.flipper-box {
    background: white;
    border-radius: 12px;
    box-shadow: var(--box-shadow);
    padding: 30px;
    margin-bottom: 20px;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 40px;
    text-align: center;
    margin-bottom: 20px;
    transition: var(--transition);
}

.upload-area:hover {
    border-color: var(--primary-color);
}

.upload-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    background: var(--primary-color);
    color: white;
    padding: 12px 24px;
    border-radius: 6px;
    cursor: pointer;
    margin: 0 auto;
    transition: var(--transition);
}

.upload-btn:hover {
    opacity: 0.9;
}

.file-info {
    margin-top: 15px;
    color: var(--light-text);
}

.controls {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.flip-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
}

button {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 15px;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition);
}

button:hover {
    opacity: 0.9;
}

button:disabled {
    background: #ccc;
    cursor: not-allowed;
}

#downloadBtn {
    background: var(--success-color);
    padding: 12px;
    font-weight: 600;
}

.result-area {
    margin-top: 30px;
}

.image-preview {
    max-width: 100%;
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
}

#imageCanvas {
    max-width: 100%;
    max-height: 400px;
    border-radius: 8px;
    box-shadow: var(--box-shadow);
}

.error-message {
    color: var(--error-color);
    padding: 15px;
    border-radius: 6px;
    background: rgba(255, 74, 74, 0.1);
    margin-top: 20px;
}

.hidden {
    display: none !important;
}

footer {
    text-align: center;
    padding: 20px;
    color: var(--light-text);
    font-size: 0.9rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .upload-area {
        padding: 20px;
    }

    .flip-buttons {
        gap: 8px;
    }

    button {
        padding: 8px 12px;
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    .flipper-box {
        padding: 20px;
    }

    .upload-btn {
        flex-direction: column;
        padding: 10px;
    }

    .flip-buttons {
        flex-direction: column;
    }
}