:root {
    --primary-color: #1a237e;
    --secondary-color: #283593;
    --accent-color: #3f51b5;
    --light-color: #e8eaf6;
    --dark-color: #0d1440;
    --success-color: #4caf50;
    --text-color: #333;
    --text-light: #666;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --radius: 10px;
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f5f7fa;
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    max-width: 1200px;
    margin: 0 auto;
    min-height: 100vh;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 30px;
    padding: 25px 20px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}

header::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M0,0 L100,0 L100,100 Z" fill="rgba(255,255,255,0.05)"/></svg>');
    background-size: cover;
}

h1 {
    font-size: 2.2rem;
    margin-bottom: 10px;
    position: relative;
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 15px;
    position: relative;
}

/* Instructions */
.instructions {
    background-color: var(--light-color);
    padding: 20px;
    border-radius: var(--radius);
    margin-bottom: 30px;
    border-left: 5px solid var(--accent-color);
    box-shadow: var(--shadow);
}

.instructions h2 {
    color: var(--primary-color);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.instructions h2::before {
    content: "📋";
}

.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 15px;
    margin-top: 15px;
}

.step {
    background-color: white;
    padding: 15px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.step-number {
    display: inline-block;
    background-color: var(--accent-color);
    color: white;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    text-align: center;
    line-height: 28px;
    margin-right: 10px;
    font-weight: bold;
}

/* Category Selection */
.category-selector {
    margin-bottom: 30px;
    text-align: center;
}

.category-selector h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.category-selector h2::before {
    content: "📁";
}

.category-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
}

.category-btn {
    padding: 12px 20px;
    background-color: white;
    border: 2px solid var(--light-color);
    border-radius: 50px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-color);
}

.category-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

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

/* Category Container */
.category-container {
    display: none;
    background-color: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 25px;
    margin-bottom: 30px;
    animation: fadeIn 0.5s ease;
}

.category-container.active {
    display: block;
}

.category-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--light-color);
    flex-wrap: wrap;
    gap: 15px;
}

.category-title {
    color: var(--primary-color);
    font-size: 1.8rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

.category-count {
    background-color: var(--light-color);
    padding: 5px 15px;
    border-radius: 20px;
    font-weight: 600;
    color: var(--primary-color);
}

/* Items Grid */
.items-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 15px;
}

.item-card {
    background-color: white;
    border: 2px solid var(--light-color);
    border-radius: 8px;
    padding: 15px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 120px;
}

.item-card:hover {
    border-color: var(--accent-color);
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.1);
}

.item-card.active {
    background-color: var(--light-color);
    border-color: var(--accent-color);
}

.item-number {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.item-preview {
    font-size: 0.85rem;
    color: var(--text-light);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    display: none;
}

/* Message Display */
.message-display {
    background-color: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 30px;
    margin-bottom: 30px;
    display: none;
    animation: fadeIn 0.5s ease;
}

.message-display.active {
    display: block;
}

.message-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 15px;
}

.message-title {
    color: var(--primary-color);
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

.message-title::before {
    content: "📨";
}

.close-btn {
    background-color: var(--light-color);
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.close-btn:hover {
    background-color: #ff5252;
    color: white;
}

.message-content {
    background-color: #f9f9f9;
    padding: 25px;
    border-radius: 8px;
    border-left: 5px solid var(--accent-color);
    font-family: 'Courier New', monospace;
    font-size: 1.1rem;
    line-height: 1.8;
    white-space: pre-wrap;
    word-break: break-word;
    overflow-x: auto;
    color: #1a1a1a;
    font-weight: bold;
}

/* Footer */
footer {
    text-align: center;
    margin-top: 40px;
    padding: 20px;
    color: var(--text-light);
    border-top: 1px solid var(--light-color);
    font-size: 0.9rem;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 15px;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .category-buttons {
        gap: 8px;
    }
    
    .category-btn {
        padding: 10px 16px;
        font-size: 0.9rem;
    }
    
    .items-grid {
        grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
        gap: 12px;
    }
    
    .item-card {
        padding: 12px;
    }
    
    .message-content {
        padding: 20px;
        font-size: 1rem;
    }
    
    .category-header, .message-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .instructions {
        padding: 15px;
    }
    
    .steps {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.5rem;
    }
    
    .category-title, .message-title {
        font-size: 1.3rem;
    }
    
    .items-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }
    
    .item-card {
        padding: 10px;
    }
    
    .item-number {
        font-size: 1.3rem;
    }
    
    .category-container, .message-display {
        padding: 20px 15px;
    }
}

/* Print Styles */
@media print {
    .category-buttons, .close-btn, footer {
        display: none;
    }
    
    .category-container, .message-display {
        box-shadow: none;
        border: 1px solid #ddd;
    }
}