Banner height in website

I have an issue with the banner on the website
the code i have used is …
<div class=“alert-dark bg-dark text-white rounded-0 border-0 mb-0 text-align: center”>
<div class=“container”>
<marquee behavior=“scroll” direction=“left”> Call +91 9xxxxxxxx8
the home page banner size is correct

after login the banner size increases

any help on this
With regards