Adding Custom CSS to Admin Area

Hi I am currently using this css in the front end of the website to get the look I want on ths domain
lynnehorwood.co.uk but the administration areas for content creation just looks white can i add the css to the admin editor area as well?
I have tried a few plugins that suggest it can be done but nothing has worked.

header.entry-header {
display: none;
}
#secondary .widget a {
color: #000;
}
.post-inner-content:first-child {
border-top: 0px
}
.post-inner-content {
background-color: #03bf99;
border-color: #03bf99
}
.well {
background-color: transparent;
border: none

		}

.main-content-inner {
border-color: #03bf99
}
.well{
box-shadow: none
}

Hey there

Well, this can not be done from the theme, try these resources:


Awesome thank you for the resources

You are most welcome here