Web design largely concerns the visual side of the site. This implies a study of colors, based on color theory and the effect they have on the perception of a brand in the users' imagination.
But we also talk about the fonts to use in the logo - depending on the type of logo you prefer - as well as on the website, the use of lines, curves, or other geometric figures. Depending on this, a more elegant and formal, more dynamic, and modern, more serious, or more friendly style can be given. The options are plentiful.
The web designer still has to take care of the shape of the buttons on the site, the presence of photographic images or simpler graphics, the visual structure of the menu and every single element with which users interact.
All these elements must be consistent with each other, to give a feeling of unity throughout the navigation of the site. If you fail to do this, giving an inconsistent and disconnected image, the credibility towards the brand that the site represents drops, decreasing the Brand Authority.