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

.container {
    display: flex;
}

.left-column {
    width: 20%;
    padding: 1em;
    background-color: #f0f0f0;
}

.right-column {
    width: 80%;
    padding: 1em;
}

ul {
    list-style-type: none;
    padding: 0;
}

li a {
    display: block;
    padding: 0.5em;
    text-decoration: none;
    color: #333;
}

li a:hover {
    background-color: #ddd;
}

.paper {
    display: flex;
    margin-bottom: 2em;
}

.paper img, .image-placeholder {
    width: 150px;
    height: 150px;
    margin-right: 1em;
    flex-shrink: 0;
    object-fit: contain;
}

.paper-details p {
    margin: 0.5em 0;
}

header {
    background-color: #cccccc;
    color: black;
    padding: 1em;
    text-align: center;
}