Don't you find this?

Don't you find that there are no scroll bar in a small browser. Just look at the PNG file in the following.

This is different from a normal website.

To get the scroll bar do this.

Edit base/css/general.css

Look for this

div.sys_root {
    position: relative;
    min-height: 100vh;
    box-sizing: border-box;

    padding-bottom: 204px;

    overflow: auto;
}

Remove the line overflow: auto; so your left with this.

div.sys_root {
    position: relative;
    min-height: 100vh;
    box-sizing: border-box;

    padding-bottom: 204px;

}

You will need to clear the dolphin cache after editing that css file.

 Thank you very much,deano. I didn't learn CSS knowledge.