body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #121212;
    color: #e0e0e0;
}

header {
    background-color: #003366;
    color: white;
    padding: 10px;
    text-align: center;
}

h1#tab-title {
    margin: 0;
    font-size: 1.5em;
}

nav {
    margin-top: 10px;
}

nav button {
    background-color: #004080;
    color: white;
    border: none;
    padding: 10px 20px;
    margin: 0 5px;
    cursor: pointer;
    border-radius: 5px;
    transition: none;
}

nav button.active {
    background-color: #00264d;
}

.content {
    padding: 20px;
    text-align: center;
    transition: none;
}

#group-selection select,
#schedule select {
    width: 80%;
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #333;
    border-radius: 5px;
    background-color: #1e1e1e;
    color: #e0e0e0;
    transition: none;
}

#group-selection button,
#schedule button {
    background-color: #228b22;
    color: white;
    border: none;
    padding: 10px 20px;
    cursor: pointer;
    border-radius: 5px;
    transition: none;
}

#schedule-content p {
    background-color: #1e1e1e;
    margin: 10px 0;
    padding: 10px;
    border: 1px solid #333;
    border-radius: 5px;
    transition: none;
}