.page_main_ttl.about_main_ttl {
    background-image: url(../images/about/about_main_img_sp.jpg);
}

@media screen and (min-width:961px) {
.page_main_ttl.about_main_ttl {
	background:url(../images/about/about_main_img_pc.jpg) center center no-repeat;
}
}