body { 
    max-width: 800px;
    margin: auto;
    font-family: sans-serif;
}

p.TODO { 
    font-weight: bold;
}

div.block {
    margin-left: 20px;
    border-width: 1;
    border-color: black;
    border-style: solid;
    padding: 10px;
}

p.lesson {
    background-color: #cccccc;
    padding: 20px;
    font-weight: bold;
    margin-top: 20px;
}