Better support for stretched-link in cards

Card blocks are extremely versatile, and tend to be used for many purposes. Frequently we want cards to become links to other sections of a website. It's easy - just add a Button Link. This however does not make the whole card clickable. To fix it, you can now add a stretched-link class to your button, and the whole card, not just the button, will become a clickable link.

What if we do not want a visible button? What if instead we want a clickable image?

You can now achieve it, add any content to a card (e.g. an image), then add a button link, with stretched-link zero-sized classes. This will create a link covering the whole card, and will hide the button.

Support for CSS variables

We've added support for custom bootstrap / mdbootstrap CSS variables. This can be used e.g. to change your primary, secondary, danger, warning, info, light, dark colors without recompiling the SCSS stylesheet.

When Layout -> Color Theme is set to "custom", it triggers loading /static/cjkcms/css/cjkcms-custom-theme.css. Define this file in your project using e.g. template copied from /static/cjkcms/css/cjkcms-custom-theme-disabled.css and redefine any css vars.