"Join Scratch" page uses old color scheme for some UI elements

[kelianor]

"Join Scratch" page uses blue colors instead of purple for background, tooltips and checkboxes.
Note: "Next" button is purple

Steps to Reproduce

1. Go to 'https://scratch.mit.edu/join'
2. Notice that background, tooltips and checkboxes use blue colors

[mrjasonn]

Please note that the next button is purple.

[ghost]

There are a couple of Color Consitencies that I've discovered when using the website, and there is a forum for all the old color UI elements in the official topic.

[blazgocompany]

In src/components/registration/steps.scss line 87:

input[type="radio"] {
            margin-right: 1rem;

            &:focus {
                transition: all .5s ease;
                border: 1px solid $ui-purple; /* Previously $ui-blue */
            }
 }
        
 

I couldn't test this so I didn't make a PR.