If you need to have the red line overwrite the text data, you can use the following code
HTML
<div class="block">
<h3><u class="underlined">ABOUT ME</u>
</div></h3>
No changes in CSS required
If you want the red line to be next to the text, then utilize the following CSS and HTML
HTML
<h3><u class="underlined">ABOUT ME</u><div class="block">
</div></h3>
CSS
.underlined {
border-bottom: 1px dotted #000;
text-decoration:none;
}
.block {
height:15px;
flex : 1;
background-color: #ff5050;
}
h3{
display : flex;
align-items: center;
}