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

body {
    background-color: #f4f7f6;
    color: #333;
    line-height: 1.6;
}

header {
    background-color: #2c3e50;
    color: #fff;
    padding: 2rem 1rem;
    text-align: center;
}

main {
    max-width: 1000px;
    margin: 2rem auto;
    padding: 0 1rem;
}

/* Upload Section Styles */
.upload-section {
    background: #fff;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    text-align: center;
}

#uploadForm {
    margin-top: 1rem;
    display: flex;
    justify-content: center;
    gap: 10px;
}

button {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background 0.3s;
}

button:hover {
    background-color: #2980b9;
}

.hidden {
    display: none;
}

#uploadMessage {
    color: #27ae60;
    margin-top: 1rem;
    font-weight: bold;
}

/* Gallery Section Styles */
.pdf-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 1rem;
}

.pdf-card {
    background: #fff;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.pdf-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.pdf-card h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    word-break: break-all;
}

.view-btn {
    text-decoration: none;
    background-color: #2ecc71;
    color: white;
    padding: 8px 16px;
    border-radius: 4px;
    margin-top: auto;
    transition: background 0.3s;
}

.view-btn:hover {
    background-color: #27ae60;
}