CSS styles for elements can come from various sources and can be layered on top of each other.
Styles are applied to elements based on a set of conflict-resolution rules within CSS, with higher-priority styles overriding those of lower priority.
Priorities are determined by the specificity of the selector; ID selectors have a higher priority than class selectors, and class selectors are higher than type selectors.
If selectors have the same level of specificity, the style defined later in the CSS will prevail.
You can increase the priority of a style by increasing the specificity of its selector or by using !important.
An example given is changing a paragraph's background to gold and then overriding it with sky blue using the same 'p' selector.
Adding a class 'bj green yellow' to the first paragraph element and defining a green-yellow background in CSS will override the 'p' selector style due to the higher priority of class selectors.
Combining selectors can further increase specificity and priority, overriding other styles, as in the example where the selector 'content > p' defines a background and supersedes the previous 'bj green yellow' background color.
Lastly, using an ID selector '#app' with a background of lavender will override the combined selector 'content p' due to the even higher priority of ID selectors.
