body {
    background: #f9f8fc;
    font-family: 'Segoe UI', Arial, sans-serif;
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.content-wrapper {
    flex: 1;
}

.banner {
    background: linear-gradient(90deg, #5a007b 0%, #6a009a 100%);
    padding: 40px 20px;
    text-align: center;
    color: white;
    box-shadow: 0 2px 12px rgba(106, 0, 154, 0.1);
}

.main-title {
    font-size: 2.5em;
    font-weight: 700;
    margin: 0 0 10px 0;
}

.subtitle {
    font-size: 1.2em;
    font-weight: 300;
    margin: 0;
}

.ppt-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
    padding: 40px;
    max-width: 1200px;
    margin: 0 auto;
}

.ppt-item {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: transform 0.3s, box-shadow 0.3s;
}

.ppt-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
}

.ppt-thumb {
    width: 100%;
    height: 180px;
    background-color: #f3e5f5;
    display: flex;
    align-items: center;
    justify-content: center;
}

.ppt-thumb img {
    max-width: 100%;
    max-height: 100%;
    object-fit: cover;
}

.ppt-title {
    font-size: 1.2em;
    font-weight: 600;
    color: #333;
    padding: 15px 20px 5px 20px;
    text-align: center;
}

.ppt-desc {
    font-size: 0.95em;
    color: #666;
    padding: 0 20px 15px 20px;
    flex-grow: 1;
    text-align: center;
}

.ppt-actions {
    padding: 0 20px 20px 20px;
    margin-top: auto;
    text-align: center;
}

.ppt-actions a {
    display: inline-block;
    padding: 8px 20px;
    border-radius: 6px;
    background: #6a009a;
    color: #fff;
    text-decoration: none;
    font-weight: 500;
    margin: 5px;
    transition: background-color 0.3s;
}

.ppt-actions a:hover {
    background-color: #5a007b;
}

.no-ppt {
    text-align: center;
    color: #888;
    font-size: 1.2em;
    padding: 50px;
    grid-column: 1 / -1;
}

.footer-banner {
    background: #f1f1f1;
    color: #555;
    text-align: center;
    padding: 25px 20px;
    margin-top: 40px;
    font-size: 0.95em;
}

.footer-banner p {
    margin: 5px 0;
}

.footer-banner a {
    color: #6a009a;
    font-weight: 600;
    text-decoration: none;
}

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

@media (max-width: 768px) {
    .ppt-list {
        grid-template-columns: 1fr;
        padding: 20px;
    }
}