.periodontal .c-mv::before {
  background-image: url(../../img/periodontal/bg_mv_periodontal_pc.webp);
}
@media screen and (max-width: 767px) {
  .periodontal .c-mv::before {
    background-image: url(../../img/periodontal/bg_mv_periodontal_sp.webp);
  }
}