I noticed that K2 Items are not fixed on smartphone screens in Portrait position.

For example, the K2 article i created, i can drag it to the left side of the screen with my finger. Looks like the fixed width is wrong for portrait modes. I tried with both 3.5-inch and 5-inch smartphone displays, and on both of them the article you are reading is movable with your finger.

With the Joomla Core articles, they are fixed no matter whether you read it portrait or landscape mode. The article is fixed on the screen. With K2, it's not.

How to fix this?

I'm already on K2 2.7 by the way.

Hello,

Are you talking about the frontend or the backend?
Are you using a custom template?

I am talking about the Frontend.

I am using Joomlart template. Articles on native Joomla, look fine.

When i installed K2, all articles created don't stay fixed on Portrait position on smartphones up to 5-inch display. Landscape is fine. Portrait, no.

K2 displays the articles a bit too wide on Portrait position. But in Landscape position, it's ok.

As a result, my website readers could drag the articles off-center from their screens if they are reading it on Portrait position. A bit annoying.

Joomlart is using its own overrides.
Since this is a template issue you need to address this issue to Joomlart.