It is not possible to apply CSS to only half of a character. CSS styles are applied to the entire element, which can include text, but not partial text or characters.

However, there are some tricks you can use to achieve a similar effect. For example, you can use a pseudo-element like ::before or ::after to add a visual element that covers half of the character. Here's an example:

HTML:

<p>The quick <span class="half-character">b</span>rown fox jumps over the lazy dog</p>

CSS:

.half-character {
 position: relative;
 display: inline-block;
}
.half-character::before {
 content: "";
 display: block;
 position: absolute;
 top: 0;
 bottom: 0;
 left: 0;
 width: 50%;
 background-color: yellow;
}

In this example, we're adding the half-character class to the span element containing the character we want to style. We're then using CSS to position the span element as inline-block and adding a ::before pseudo-element that covers the left half of the character using absolute positioning and a background color.

Again, this is not applying styles to only half of the character itself, but adding a visual element that appears to cover half of the character.