Narrow paragraph block aligned to left of “wrapper”

Adding my solution so far, though it doesn’t seem ideal to me. Also the .entry-content parent doesn’t get applied in the editor.

/* trick to have root paragraphs left-aligned "in the central wrapper" without extra dom */
.entry-content > p{
    padding-right:calc(1264px - 830px);
    max-width:1264px;
    box-sizing:border-box;
}
@media only screen and (max-width:1300px){
    .entry-content > p{
        padding-right:calc(100% - 830px);
    }
}