#left_side {
   width: 190px;
}

#right_side {
   width: 520px;
}
   
.selected_choice {
   color: black;
}

.chapter ul {
   padding-left: 2em;
}

.links {
   margin-top: 35px;
}

#main_content h1 {
   border-bottom: 0;
   padding-bottom: 0;
}