body {
    font-family: 'Arial', sans-serif;
    background-color: #333;
    color: #fff;
    margin: 25px;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    transition: background-color 0.5s ease-in-out;
}

.dark-theme {
    background-color: #111;
    color: #fff;
}

header {
    background-color: #222;
    color: white;
    text-align: center;
    padding: 20px;
    border-bottom: 2px solid #444;
}

h1 {
    margin: 0;
}

nav {
    position: absolute;
    top: 10px;
    right: 10px;
}

#theme-toggle {
    background-color: #444;
    color: #fff;
    border: none;
    padding: 10px 15px;
    font-size: 1em;
    cursor: pointer;
    border-radius: 5px;
    transition: background-color 0.3s ease-in-out;
}

#theme-toggle:hover {
    background-color: #555;
}

#theme-toggle::before {
    content: '\1F319';
    margin-right: 5px;
}

#theme-toggle.dark-theme::before {
    content: '\2600';
}


main {
    text-align: center;
    margin: 20px;
}

.lecture {
    background-color: #444;
    border-radius: 10px;
    padding: 15px;
    margin: 10px 0;
    transition: transform 0.3s ease-in-out;
}

.lecture:hover {
    transform: scale(1.02);
}

h2 {
    margin-bottom: 5px;
}

ul.page-list {
    list-style-type: none;
    padding: 0;
    display: flex;
    justify-content: center;
}

li {
    margin: 0 15px;
}

a {
    text-decoration: none;
    color: #66ccff;
    font-weight: bold;
    transition: color 0.3s ease-in-out;
}

a:hover {
    color: #ff6600;
}

footer {
    background-color: #222;
    color: white;
    text-align: center;
    padding: 10px;
    position: fixed;
    bottom: 0;
    width: 100%;
    border-top: 2px solid #444;
}