Change header image size (I found simple solution)

I watched many options in this forum, but I’ll put something that seems less complicated.

First I have Jetpack plugin and activated the box: CSS Custom (a very good option to avoid “child templates”).

The code to enter is one that we have on line 551 of the stylesheet (style.css) template. The default is as follows:

#branding {
	float: left;
	width: 45%;
	overflow: hidden;
}

We want the real size of our banner. To do this we should increase the percentage of the width.

#branding {
	float: left;
	width: 100%;
	overflow: hidden;
}

My example (width: 50%):
https://joanmorci.com/

Each template has the option in different names.

Greetings from Spain!
Pd .: I have the ‘Oxygen template’ in version 0.5 instead of 0.5.4 (not sure what changes did, and don′t know where to see them).