To improve keyboard accessibility, the "Skip to main content" link should appear when the user presses Tab for the first time after opening a page.

In Safari, this button does not appear. When the user continues pressing Tab, the focus moves from the search field directly to the page content, skipping the main sidebar menu.

Steps to reproduce:

1. Open any Zabbix frontend page in Safari.
2. Press Tab to navigate through the page.

Actual result:
The "Skip to main content" link does not appear. After the search field, the focus moves directly to the page content, skipping the sidebar menu.

Expected result:
The behavior should be the same as in Firefox and Chrome. The "Skip to main content" link should appear when Tab is pressed for the first time, allowing the user to choose whether to skip navigation and move directly to the main content.