Combining CSS can't work

[targetmarts]

Hello all.
I just try to Combining CSS as https://www.zen-cart.com/showthread....-Combining-CSS said: combining all stylesheet*.css code to stylesheet.css, and delete all stylesheet*.css.
But it work Cluttered.
Why????

you can see my site www.targetmarts.com have many css js template images,so i will try to combining js and images also,what i'll Be careful for this Situation?

and how to delete the red header as Categories sidebox-header-left?

[davewest]

But it work Cluttered.
Why????

You need to understand what Cascading Style Sheets is and how the rules work first!
Suggest some studying before you edit.

w3schools(dot)com or developer.mozilla(dot)org

so i will try to combining js and images also,what i'll Be careful for this Situation?

Same here, if you don't follow some basic rules, you can do more damage then good.