body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
}

.container {
    display: flex;
    border: 1px solid #ddd;
    height: 400px;
}

.column {
    flex: 1;
    border-right: 1px solid #ddd;
    padding: 10px;
    overflow-y: auto;
}

.column:last-child {
    border-right: none;
}

.item {
    padding: 8px;
    margin: 4px 0;
    cursor: pointer;
    border-radius: 4px;
}

.item:hover {
    background-color: #f0f0f0;
}

.selected {
    background-color: #fffacd;
    font-weight: bold;
}

h2 {
    margin-top: 0;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
}

.content {
    padding: 15px;
    line-height: 1.6;
}