How Can I Create Custom Underline Or Highlight For Text In Html Or Css?

I'm trying to figure out how to create a custom background effect for text. In other words, how can I make something like this:

Solution 1:

Use the <mark> element and tweek the line-height

mark {
  display: inline-block;
  line-height: 0em;
  padding-bottom: 0.5em;
}

<h1><mark>Lorem ipsum</mark></h1>

Solution 2:

A very good article explains a nice way to do that with gradients: https://thirtyeightvisuals.com/blog/low-highlight-heading-links-squarespace

.highlight {
  background: linear-gradient(180deg,rgba(255,255,255,0) 50%, #FFD0AE50%);
}

Solution 3:

For these I usually use an SVG pixel (a 1x1 stretchable HTML-encoded SVG with a fill color) that we can manoeuvre anyway we want:

h1 {
  background: url("data:image/svg+xml;charset=utf8,%3Csvg version='1.1' xmlns='http://www.w3.org/2000/svg' x='0px' y='0px' width='1px' height='1px' viewBox='0 0 1 1' preserveAspectRatio='none'%3E%3Crect x='0' y='0' width='1' height='1' fill='red' /%3E%3C/svg%3E") no-repeat 100%100%;
  background-size: 100%50%;
}

<h1>My Text</h1>

This also allows for animations to be easily added. This only works on single-line items, however. You can change the color inside the svg fill property. If encoded it works on IE9+, so it's pretty compatible! Just remember that the hash sign in front of hex colors needs to be encoded as well - its %23 (personally I use sass to encode it for me).