[mn="1000"] { 
    /* text-align: center */
}
[mn="1000"] ._subttl {
    margin: 0 0 30px;
    padding: 0 0 15px;
    font-size: 120%;
}
[mn="1000"] ._subttl:after {
   content: '';
   bottom: 0;
   left: 0;
   display: block;
   position: absolute;
   height: 3px;
   width: 300px;
   max-width: 80%;
   background-color: var(--clr01);
}