Ranges based on Bootstrap
animated progress-bar with boostrap tooltip on it.
Flip cards using Bootstrap 4
Bootstrap Year Calendar.
Here w3 tweaks explored the hide and show the header on scroll using headroom.js and Bootstrap. On scroll up hide the header and scroll down show the header. This Headerroom.js designed only for header show and hide on scroll up and down.
This contact form bootstrap tutorial with validation will be the good practice to validate the form and easy to validate the form. This tutorial will help to build bootstrap website with best form validation using bootstrap 3 validation.