Why my bootstrap css is not working on mobiles?

Bootstrap css is not working on mobiles when all is fine in your Bootstrap html code.
and when you open your site on mobile then it shows as  it shows onn your pc.
and you still you are frustrate that why Bootstrap css is not working.
so please check your meta tag
did you add this code in of head tag of html


<meta name="viewport" content="width=device-width, initial-scale=1.0" />

 most of the people when create Bootstrap css the forgot to add this on head tag in html thats why this css not working on mobiles browser so add this code in head tag of html code

 <meta name="viewport" content="width=device-width, initial-scale=1.0" />