Hi all, changing the height of  header.jpg  in oxwall 1.6.0 origin theme `s  css-file resulted in a page without any text-formating and the header.jpg disappeared.
I did the following: In Admin Section I copyed the complete read only css-file into the box below. I changed the height

.ow_header_pic {
    height: 209px;    to

.ow_header_pic {
    height: 100px;

clicked on the save button and then the site lost all text-formating like bold text and the header.jpg disappeared.

Meanwhile I also read this article > http://docs.oxwall.org/overview:custom_design

So my 3 questions:

Inside the box below the read only css-file - is it OK to insert things like

.ow_header_pic {
    height: 100px;    only ?

 or do I have to insert the complete modified css-file ? 

2nd question: Is it enough to change the values in the css-file which I can see in the Admin-Section or do I have to change those values in the system`s base css  also ?

3rd question:
Will I have to switch to DEV mode before changing css values ?

Thanks in advance, Jochen