customize title + table of contents

first I want title h1 full width yellow color
second table of contents
third the content

I have this code

@media (max-width: 768px) {
.site-content {
flex-direction: column-reverse;
}
}

@media (max-width: 768px) {
.main-navigation button.menu-toggle {
margin-left: auto;
margin-right: auto;
}
}

h1 {
display: block;
background-color: #FFFF00;
padding: 5px;
}

website: https://elmejorproducto.com/champus/anticaspa/