The background of the entire page comes from:-
html, body{
stuff
}
[/color]
The same rule loads and positions the page-gradient image that sits up the top of the page - what confuses you is that the image is loaded as base64 encoded string (it reduces requests).
If you force the background colour in
conf/userstyle.css e.g.:-
html, body{
background: aqua;
}
[/color]You'll likely be very disappointed as it applies to the whole page (which is better done in
do=admin&page=styling anyway), rather than just the header area. So you have (at least) three options:-
;customise the template
CSS; over-ride the image used in the page (html, body - background: image top left blah) or, apply a style that applies to the actual header div (
dokuwiki_header). The last two approaches can be done by adding a custom style to
conf/userstyle.css and will survive updates.
CSS is outside the scope of this forum (sorry) - but you'll find plenty of examples that will guide you on using
userstyle.css in this
forum.
That said:-
conf/userstyle.css
html, body {
background: #fbfaf9 url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAABzCAYAAABZ/2hDAAAABmJLR0QA/wD/AP+gvaeTAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB3RJTUUH4AoZCTsYnT79dwAAAMtJREFUKM/dj81KA0EYBGvqm5nNJsSDb+lJ8J0FkWCiIMn+jofsQXwEL33p6m6a55enZkRgzhn7fo+hWErFruuQlDCRsO97LLlgLhlzZMylYFcrksRIYjKhuiH17ibuQ4fDEcu9IHCZR7wNX/hwfMRaO8ylombUwIi8ZVNKOAwDns9nPJ0uuO8rRgLHccLv6xXnNiGx4jLP+Pb6jsu6bMjl4xNpDef5hihCw9bAdVlxvE1IAxtscFsbAr8lDKy7HdZcsJSyPf/D/U/5AZc+QIhB1h2MAAAAAElFTkSuQmCC) top left repeat-x;
}
[/color]
will give you a garish gradient image behind the header area (in the body). A 1x115px png image using RGB colour space (72x72ppi) that has been base64 encoded. In Linux that's
base64 $imagefile e.g.
base64 page-gradient.png
iVBORw0KGgoAAAANSUhEUgAAAAEAAABzCAYAAABZ/2hDAAAAmElEQVQoz+3IIU5DURRF0X32ff2/
oQlp6yDB1CGYAAMgwTCMjhwMDoEr72KYAq5LLlhvHyROIS2hpdN/p1NwitWStGS0OKb0RMYyBVJc
tovsb6awpLiMjRx2CDsqP5Z93Ee+q4uxDjlskfduuZtIgvlYpn0ilU2Uz/u2nypkdRT9Enn+Cgkl
/UrlsYNB+/gGAhJin89c/adf1hUppirdLEYAAAAASUVORK5CYII=
[/color]
A quick Google should find you online tools that will do that for you.