body {
    font-family: 'Malgun Gothic', 'Dotum', sans-serif;
    background-color: #f4f6f9;
    margin: 0;
    padding: 0;
    color: #333;
}

header {
    background-color: #3b5998;
    color: white;
    text-align: center;
    padding: 20px 0;
}

header h1 {
    margin: 0;
    font-size: 28px;
}

header p {
    margin: 5px 0 0;
    font-size: 14px;
    opacity: 0.8;
}

nav {
    background-color: #2d4373;
    margin-top: 15px;
}

nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
}

nav ul li a {
    display: block;
    padding: 15px 30px;
    color: white;
    text-decoration: none;
    font-weight: bold;
}

nav ul li a:hover {
    background-color: #1e2e50;
}

.container {
    width: 800px;
    margin: 30px auto;
    background-color: white;
    padding: 40px;
    border: 1px solid #ddd;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 30px;
    table-layout: fixed;
}

td {
    border: 1px solid #ccc;
    padding: 20px;
    text-align: center;
    vertical-align: middle;
}

.date-header {
    background-color: #e9eef5;
    font-size: 18px;
    font-weight: bold;
    color: #3b5998;
}

.sub-text {
    font-size: 14px;
    font-weight: normal;
    color: #555;
    margin-top: 5px;
    display: block;
}

.box-title {
    font-size: 14px;
    color: #888;
    font-weight: bold;
    margin-bottom: 15px;
    text-align: left;
    border-bottom: 2px solid #eee;
    padding-bottom: 5px;
}

.category-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.category-list li {
    margin-bottom: 10px;
}

.category-list li a {
    display: block;
    padding: 15px;
    background-color: #f8f9fa;
    border: 1px solid #ddd;
    color: #333;
    text-decoration: none;
    font-weight: bold;
    border-radius: 5px;
    transition: background 0.2s;
}

.category-list li a:hover {
    background-color: #e2e6ea;
    color: #3b5998;
}

.shortcut-links p {
    font-size: 14px;
    color: #555;
    margin-bottom: 15px;
    line-height: 1.5;
}

.btn {
    display: inline-block;
    background-color: #3b5998;
    color: white;
    padding: 10px 20px;
    text-decoration: none;
    border-radius: 4px;
    font-size: 13px;
}

.quote {
    font-size: 18px;
    font-weight: bold;
    color: #444;
    font-style: italic;
}

hr {
    border: 0;
    border-top: 1px dashed #ccc;
    margin: 40px 0;
}

.media-section {
    text-align: center;
    margin-bottom: 50px;
}

.media-section h3 {
    border-left: 5px solid #3b5998;
    padding-left: 10px;
    text-align: left;
    margin-bottom: 20px;
    color: #333;
}

.media-section img, 
.media-section iframe, 
.media-section audio {
    border: 1px solid #ddd;
    padding: 5px;
    background-color: #fff;
    width: 400px;
    max-width: 100%;
}

.section-header {
    color: #3b5998;
    border-bottom: 2px solid #3b5998;
    padding-bottom: 10px;
    margin-top: 0;
}

.exercise-table th {
    background-color: #3b5998;
    color: white;
    padding: 12px;
}

.exercise-table td {
    text-align: left;
    padding: 12px;
}

.exercise-table tr:nth-child(even) {
    background-color: #f9f9f9;
}

footer {
    text-align: center;
    padding: 20px;
    background-color: #eee;
    color: #666;
    font-size: 12px;
    border-top: 1px solid #ddd;
    margin-top: 30px;
}