Style "splitting" at breakpoint, mediaqueries - css

Question

I'm working on developing a style for a site and I'm using media queries as breakpoints. At the breakpoint, the page suddenly decides to listen to some style from the first interval, and some from the second. Please help.
I've tried changing the values of the viewports but this doesn't work. I hope this problem is obvious to someone with more experience than I, because I really don't know what to do.
#media (min-width: 500px) and (max-width: 768px) {
(ex.) #randomDiv {
background-color: blue;
width: 100px;
}
}
#media (min-width: 768px) and (max-width: 1023px) {
(ex.) #randomDiv {
background-color: red;
width: 300px;
}
}
When the viewport hits 768px it decides to mix styles, p.e. the background color changes to red, but the width doesn't change. Does anyone know what I'm doing wrong? After 768px (769px <) everything works just fine, as well as before 768px. Please help.

Answer 1

When using media queries to make your frontend code responsive, it is quite useful to think about the base or starting styles then use the queries to alter those styles in one direction only. What I mean is instead of using max-width and min-width in your queries, start with the non-query styling then override those rules with either min-width OR max-width but not both. This way the changes are seamless and you only need to think about the exact breakpoint location and which styles are being overridden.
In using this approach the order of the media queries in your stylesheet matter too. Notice the widest query goes first here, if I were using min-width instead it would go the other way around.
Try looking at this in "Full page" mode and change the size of your screen down from full width.
#randomDiv {
color: white;
margin: 0 auto;
padding: 20px;
/* only background-color & width will change */
background-color: purple;
width: 90%;
}
#media (max-width: 1023px) {
#randomDiv {
background-color: red;
width: 300px;
}
}
#media (max-width: 768px) {
#randomDiv {
background-color: blue;
width: 100px;
}
}
<div id="randomDiv">I am so random.</div>