Minimize youtube header by pushback

/* ==UserStyle==
@name         Minimize youtube header
@version      20211226.07.29
@namespace    userstyles.world/user/pushback
@description  [en]Minimize the YouTube header and display it with the mouse hover.

[jp]YouTubeのヘッダーを最小化し、マウスホバーで表示する。
@author       pushback
@license      No License
==/UserStyle== */
@-moz-document url-prefix("https://www.youtube.com/watch") {
    #masthead-container {
        height: 7px;
        overflow: hidden;
    }
    #masthead-container:hover {
        height: auto;
    }
    #page-manager{
        margin-top: 0 !important;
    }
    #primary {
        margin-top: 0 !important;
        padding-top: 7px !important;
    }
}