CSS to hide the entire first week of a calendar on mobile, but only if none of the days in that first week are selectable (--disabled)

calendar.sass

.cal-day--disabled
  display: none
  @media screen and (min-width: 450px)
    display: block

.cal-day:not(.cal-day--disabled)
  ~ .cal-day
    display: block

.cal
  .cal-day--disabled:first-child
    + .cal-day--disabled
      + .cal-day--disabled
        + .cal-day--disabled
          + .cal-day--disabled
            + .cal-day--disabled
              + .cal-day--disabled
                ~ .cal-day
                  display: block