Cleaning up css code in argent

Hello,

this probably isn’t solely argent theme related but everyone has always been really helpful in here so I thought I would ask…

I have created a landing page and hidden 4 elements using custom CSS, but they are all separate code entries, is there a way i can consolidate them all in to one entry? I have tried but they all wipe each other out.

the only thing i have done to each of them is Display: None

Ideally id like all 4 elements in one to tidy up my code, is that possible?

Currently i have them all separate like so;

.post-795 .entry-header {
display: none
}

.postid-795 .main-navigation {
display: none
}

.postid-795 .site-header {
display: none
}

.postid-795 .saboxplugin-wrap {
display: none
}

.postid-795 .footer-widget-area {
display: none
}

If its not possible no worries.

Does having a lot of custom CSS slow a site down? I have 164 lines of it now and am concerned.

Thanks for any help