Landing Page Enhancements

[james--jiang]

Join would take you to down to the Register section of landing page
Learn would take you down to the “envelopes”
Share would take you down to “share”
New icons for Case Studies
New icon for Methods
When you are not logged in and go on tDX it takes you down to the register section

[juliakramer]

The Join link on the landing page looks great! However, if you're already logged in then clicking the link is confusing because it just jumps you down to the bottom of the page. Perhaps we can add functionality where clicking Join while logged in sends you to a screen that says "Welcome, Julia! We see you're already logged in. Would you like to invite others to theDesignExchange? Write their email addresses here"