Here are some common CSS mistakes we all make

[charlesprabhu]

Not Using a Proper CSS Reset. Web browsers are our fickle friends.
Over-Qualifying Selectors.
Not Using Shorthand Properties.
Using 0px instead of 0.
Using Color Names Instead of Hexadecimal.
Redundant Selectors.
Redundant Properties.
Not Providing Fallback Fonts.

[sgrcatering]

Even seasoned developers slip up with CSS from time to time. One common mistake is overusing !important, which can create specificity nightmares. Another is not using a CSS reset or normalize file, leading to inconsistent styling across browsers. Many also forget mobile responsiveness, neglecting media queries. Improper use of class names, not organizing stylesheets, or ignoring browser compatibility issues can also result in unexpected, frustrating design glitches.

[Anabolic]

CLS : Cumulative Layout Shift. This was a nightmare for me to optimize. Images were bouncing around everywhere, scrolling was not smooth, mobile was not responsive, and Google was throwing penalties at me left and right. Sometimes people have pesky plug-in's that destroy your work.