Navin Rauniyar questions

• How can I detect if a browser supports a viewport unit, like vh or dvh?
• Can I use both version of bootstrap?
• input type text width is different in chrome and firefox
• How to get `background-color` property value in Javascript? [duplicate]
• How to append text to current position?
• difference between numbers using or without using variable
• How to save working notes?
• Is this a typo in html5shiv?
• how to check falsy with undefined or null?
• What are the orphans and widows in css?

Navin Rauniyar answers