By the end of this video your own logo is in the header, and you know why making it bigger is not a theme setting.
Swapping the image
- Go to
/admin/appearance/settings/drupal8_w3css_theme. - In the Logo image section, untick Use the logo supplied by the theme. Two fields appear.
- Either use Upload logo image to send a file from your computer, or type an existing path into Path to custom logo — useful when the file is already deployed with the code.
- Save the configuration and reload any page.
If nothing appears
The logo is drawn by the Site branding block, not by the page template, and that block has its own toggles. Go to /admin/structure/block, find Site branding in the Header region, click Configure, and confirm Site logo is ticked. A theme setting that points at a real file and a block that is not asked to print it look identical from the front end.
What the theme wraps around it
The branding template links the image to the front page, marks it rel="home", and gives the wrapper the classes w3-left w3-padding-16 site-logo. The <img> takes the alt text "Home". That is a reasonable default for a logo that acts as the home link, but if your logo carries the company name as artwork, consider whether a screen reader user is better served by that name.
About the size
The logo's dimensions come from the theme's CSS, not from a settings field, so uploading a larger file will not make it render larger. Change it by targeting .site-logo img in a sub-theme stylesheet — the same sub-theme you should already be using for custom CSS. The theme ships an SVG logo, and SVG is the format to supply if you want it crisp at any size.
While you are in the form
The favicon works exactly the same way: untick Use the favicon supplied by the theme and upload your own.
See the W3CSS Theme project page for the rest of the settings, and accessible Drupal theming for how to handle logo alt text properly.
Working out how this fits a site you already run? Drupal architecture services, and the full service list.
