Applying a color on HTML elements is not limited to one flat hue. CSS provides the ability to use color transitions, otherwise known as gradients, on elements. This is accessed through the `background` property's `linear-gradient()` function. Here is the general syntax:
`background: linear-gradient(gradient_direction, color 1, color 2, color 3, ...);`
The first argument specifies the direction from which color transition starts - it can be stated as a degree, where `90deg` makes a horizontal gradient (from left to right) and `45deg` makes a diagonal gradient (from bottom left to top right). The following arguments specify the order of colors used in the gradient.
Use a `linear-gradient()` for the `div` element's `background`, and set it from a direction of 35 degrees to change the color from `#CCFFFF` to `#FFCCCC`.