(As you can see) the .markdown-source-view.mod-cm6 selector here is applying styling to the editing (Live Preview) mode only.
To cover reading mode, you’ll need to add selectors for that as well. This seems to work, the only caveat being that if you go past six levels, all the bullets in reading mode will pick up that last “Small bullet”. If you can live with that, this should work.
.markdown-source-view.mod-cm6 .HyperMD-list-line-1 .list-bullet:after {
/* Bullet */
height: 5px;
width: 5px;
border-radius: 50%;
}
.markdown-source-view.mod-cm6 .HyperMD-list-line-2 .list-bullet:after,
ul>li> ul>li> .list-bullet::after {
/* Hollow Bullet */
height: 4px;
width: 4px;
background-color: Transparent;
border-color: var(–bullet-new-color);
border-style: solid;
border-radius: 50%;
border-width: 1px;
}
.markdown-source-view.mod-cm6 .HyperMD-list-line-3 .list-bullet:after,
ul>li> ul>li> ul>li> .list-bullet::after {
/* Solid Square */
height: 5px;
width: 5px;
border-radius: 0%;
}
.markdown-source-view.mod-cm6 .HyperMD-list-line-4 .list-bullet:after,
ul>li> ul>li> ul>li> ul>li> .list-bullet::after {
/* Dash */
height: 1px;
width: 7px;
border-radius: 0%;
}
.markdown-source-view.mod-cm6 .HyperMD-list-line-5 .list-bullet:after,
ul>li> ul>li> ul>li> ul>li> ul>li> .list-bullet::after {
/* Hollow Square */
height: 4px;
width: 4px;
background-color: Transparent;
border-color: var(–bullet-new-color);
border-style: solid;
border-radius: 0%;
border-width: 1px;
}
.markdown-source-view.mod-cm6 .HyperMD-list-line-6 .list-bullet:after,
ul>li> ul>li> ul>li> ul>li> ul>li> ul>li> .list-bullet::after {
/* Small Bullet */
height: 2px;
width: 2px;
border-radius: 50%;
}
Also, have a look at the forum formatting tips. For next time. 