Final answer:
To change the color of an underline, use the 'text-decoration-color' property in CSS. For older browsers, a workaround is using a linear gradient with the 'background-image' property.
Step-by-step explanation:
To change the color of the text-decoration underline in CSS, you can use the text-decoration-color property or the shorthand text-decoration that includes style, thickness, and color. Another approach is utilizing the background-image property with a linear gradient for more complex or cross-browser solutions.
Here is an example using the text-decoration-color property: /* CSS Code */ a. special Underline {text-decoration: underline; -web kit-text-decoration-color: red; /* For Safari */text-decoration-color: red; /* Standard syntax */}. For older browsers that do not support text-decoration-color, you could use a workaround with background-image: /* CSS Code */ a. complex Underline {background-image: linear-gradient(to right, transparent, transparent 3px, red 3px, red); background-repeat: no-repeat; background-size: 100% 1px; background-position: 0 100%;}