css
/* General Styles */
body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    color: #333;
}

/* Container styles */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header styles */
.header {
    background: #003366; /* Dark Blue */
    color: #fff;
    padding: 20px;
    text-align: center;
}

.header h1 {
    margin: 0;
}

/* Topic Styles */
.topic {
    margin: 30px 0;
}

/* Topic Description */
.topic-description {
    font-size: 1em;
    color: #444;
    margin: 10px 0;
}

/* Topic Image */
.topic-image {
    width: 100%;
    max-height: 300px; /* Adjust height as necessary */
    object-fit: cover;
    border-radius: 8px;
}

/* Video card styles */
.video-card {
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin: 20px;
    padding: 15px;
    display: inline-block;
    width: calc(80% - 40px); /* Two cards in one row with margin adjustment */
    vertical-align: top; /* Align on top */
}

/* Chapter Image */
.chapter-image {
    width: 150px; /* Altered size: increased to 150px to make it three times bigger */
    height: 150px; /* Altered size: increased to 150px for height */
    float: left; /* Align to the left */
    margin-right: 15px;
    border-radius: 5px;
}

/* Card Content */
.video-card h3 {
    margin: 0 0 10px;
    font-size: 1.3em;
}

.video-card p {
    font-size: 0.9em;
    color: #666;
}

/* Button Styles */
.button {
    background: #003366; /* Dark Blue */
    color: #fff;
    padding: 10px 15px;
    text-decoration: none;
    border-radius: 5px;
    display: inline-block;
    margin-top: 10px;
    transition: background 0.3s;
}

.button:hover {
    background: #002244; /* Darker shade of Dark Blue */
}

/* Link Styles */
.link {
    display: inline-block;
    margin-top: 5px;
    color: #3498db;
    text-decoration: none;
}

.link:hover {
    text-decoration: underline;
}

/* Footer styles */
footer {
    padding: 20px;
    text-align: center;
    background: #003366; /* Dark Blue */
    color: #fff;
    margin-top: 20px;
}

/* Responsive Styles */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }

    .video-card {
        margin: 10px 0;
        width: 100%; /* Stack cards on small screens */
    }

    .video-card h3 {
        font-size: 1.2em;
    }

    .button {
        padding: 8px 12px;
    }
}