Luutz I can only use the themes that are made ready on the built in freeflarum extensions, right?
No, you can write your own theme extension. Or, much simpler to beginn with and the only way with FreeFlarum, tinker with some CSS rules in your browser (e.g. 'inspect element' in Firefox when you right click any part of a website) and once you have found a new rule you like you can copy the CSS rule into the 'custom CSS' box under the 'appearance' section of your admin panel.
One example: Let's assume, you want to change the background color of quotes in a discussion. In the browser right click on any quote and choose 'inspect element'. You should find yourself in the middle of the <blockquote> element:
<blockquote class="uncited">
<div>
<p>
<a href="https://discuss.flarum.org/d/7585/1337" class="PostMention" data-id="131304">Sanguine</a>
What is the old way? Is this FF related?
</p>
</div>
</blockquote>
The <p> element will likely be collapsed and look like <p>...</p>, you can open it if you are interestet in the innards.
Now you have to search for the background color, it could be applied to the <blockquote> element, the <div> inside or the <p> element. It turns out to be in the <blockquote> element:
.Post-body blockquote {
font-size: inherit;
border: 0;
border-top-color: currentcolor;
border-top-style: none;
border-top-width: 0px;
border-bottom-color: currentcolor;
border-bottom-style: none;
border-bottom-width: 0px;
background: #e7edf3;
color: #667d99;
border-radius: 4px;
padding: 8px 15px;
border-top: 2px dotted #fff;
border-bottom: 2px dotted #fff;
margin: 1em 0;
margin-top: 1em;
}
Change the value of background as you like, eg. a little bit darker: #d7dde3.
Now copy the CSS block and remove anything you don't need, that's what you put into your 'custom CSS' box:
.Post-body blockquote {
background: #d7dde3;
}
Et voilá, you first customization of your Flarum instance.
