Create main frontend page

[gksoriginals]

Update templates/index.html and static/style.css.

Requirements

• Field for adding original link.
• Button for shorten the link.
• On clicking the shorten button, another editable field should appear with the shortened link.
• On editing another button should appear to save the custom link.

NOTE: This is the basic workflow, suggest better one in comment.

[decoded-cipher]

Just a try :
#11