The CSS editor in Silex free website builder is useful when you want to add CSS rules to your website:
Open the editor with the view menu, CSS style editor item.
CSS style editor
There you can add standard CSS rules, feel free to get started with CSS here.
When you add a CSS rule to your website in the CSS editor, it is applied to the whole website, not just an element - e.g. this changes the border of all the elements of your website:
border: 1px solid black;
You also can target specific elements with the CSS classes which are applied by Silex:
This is an example of what can be added in the CSS editor to change the font of all titles in your website
font-family: "calibri", Garamond, 'Comic Sans';
To discuss these classes and know more about how to use them, see this discussion about styles in Silex
The CSS rules may select an element, e.g. this changes the background color of the elements with class name my-css-class:
To apply this style to an element, you will want to add the class name my-css-class to it. To do so, enter Silex advanced "Apollo" mode with tools > Apollo mode.
Then select an element. In the properties you will see a text filed named "CSS classes" (the single line text input). Add a class name there, for example my-css-class.
Several useful links which discuss styles, effects and CSS techniques in Silex
Widgets to apply effects in your website
And the events by the pageable plugin
This page needs an examples for each class available in Silex