Set wizard-specific variables for all values

Replaced all hard-coded values and direct Bootstrap dependencies with wizard-specific variables, allowing for easy overriding when needed.
If the variables aren't touched, the output remains the same. If the Bootstrap variables are changed, the output is changed accordingly.
Also added a border property, none by default, which can also be overridden if necessary.

I used these changes to override the wizard's appearance from outside the wizard's .less file. Super practical!