body {
    margin: 0;
    font-family: sans-serif;
}

.layout {
    display: flex;
    min-height: 100vh;
    width: 1600px;
}

.sidebar {
    width: 240px;
    flex-shrink: 0;
    background: #fff;
    border-right: 1px solid #ddd;
    padding: 16px 0;
    display: flex;
    flex-direction: column;
}

.content {
    flex-grow: 1;
    padding-left: 100px;
}

.nav-heading {
    display: block;
    background-color: #008080;
    color: #fff;
    padding: 8px 12px;
    font-weight: bold;
    text-decoration: none;
    margin-top: 6px;
}

.nav-mid {
    display: block;
    background-color: #e8f3e0;
    color: #333;
    padding: 6px 12px;
    font-weight: bold;
    text-decoration: none;
    margin-top: 4px;
}

.nav-sub {
    display: block;
    padding: 4px 12px 4px 20px;
    text-decoration: none;
    color: #555;
}

.nav-sub:hover {
    background: #e0e0e0;
}