Request form page at Customer Portal doesn't load on top the page

Summary

Request form page at Customer Portal doesn't load on top of the page when the form size longer than the browser. It didn't works to certain browser , but it works for Chrome.

Environment

• IE 11
• Firefox 45

Steps to Reproduce

1. Add more than 15 fields and additional 1 Multiple Line custom fields to Customer Portal request type .
2. Access customer portal , and raise a request .

Expected Results

Request form page load from the top of the page with all type of fields.

Actual Results

Request form page doesn't load from the top of the page when have Multiple Line custom fields added.

Workaround

Use Chrome browser.