Font size changing while loading alert window through Javascript in response.write()

[netking]

I am using javscript to open a alert window when a button is clicked.

Here is the code in cs file :
Response.Write("<script>alert('hai')</script>");

Interesting thing is with the click of button, the font size changed (increased) in the original asp.net page; refreshing the screen brings back the original font size.

The problem seems to point to the javascript I used; thank you in advance for your help.