H1 {
     font-size: 24pt;
     color: blue;
     letter-spacing: 5px;
}

H2 {
     font-size: 16pt;
     font-style: italic;
     color: green;
     letter-spacing: 4px;
}

HR {
     background-color: green;
}

DIV.code_src {
    background: yellow;
    color: blue;
}

DIV.abstract {
    background: black;
    color: cyan;
}