SharePoint Online Classic - Increase size of promoted link tiles to 275px using CSS

My latest attempt:

<style type="text/css">

  /*  tile row height */
.ms-promlink-body {
    height: 285px;
    width: 870px;
  }

  /*  tile dimensions, including space between tiles */
.ms-tileview-tile-root {
    width: 285px !important;
    height: 285px !important;
  }

/*  tile overlay dimensions */
.ms-tileview-tile-content {
    width: 275px !important;
    height: 275px !important;
  }

  /*  title and description overlay dimensions */
div.ms-tileview-tile-detailsBox {
    width: 275px !important;
    height: 275px !important;
      }

  /*  tile background image dimensions */
.ms-tileview-tile-content > a > img {
    width: 275px !important;
    height: 275px !important;
  }

 /* image dimensions */
.ms-tileview-tile-content img {
    width:275px !important;
    height:275px !important;
}

  /*  title and description text  */
 .ms-tileview-tile-detailsListMedium {
    background-color: rgba(0, 0, 0, 0.3);
    height: 275px;
    padding: 4px 7px 7px;
    font-size: 14px;
    line-height: 17px;
    top: 40px !important;
  }

  /*  description text class  */
.ms-tileview-tile-descriptionMedium {
    padding-top: 15px;
    font-size: 14px;   
  }

  /*  title text when description not shown  */
.ms-tileview-tile-titleTextMediumCollapsed {
    background-color: rgba(0, 0, 0, 0.3);
    width: 275px;
    height: 40px;
    position: absolute;
    top: 130px; 
    left: 0px;
    padding: 4px 7px;
    font-size: 14px;
    line-height: 17px;
  }

.ms-tileview-tile-titleMediumCollapsed {
    height: 200px;
    overflow: hidden;
    vertical-align: bottom;
    top: 200px !important; 
}

 </style>

Yields an additional background/layer between the title and the image when just viewing the tile:

Here is some code I used a while back.  I want to say if you set ul.ms-tileview-tile-detailsListMedium to 0px in the below, it will do what you are looking for.  I dropped all of the code in case you want other ideas/ notes, especially the text centering.  Promoted links has a lot of layers to it.

<style type="text/css">
.ms-promlink-header {DISPLAY: none !important}

/* tile row height */
div.ms-promlink-body {
height: 100px;
}

/* tile dimensions, including inter-tile margin */
div.ms-tileview-tile-root {
width: 110px !important;
height: 110px !important;
}

/* tile and title( + description) overlay dimensions */
div.ms-tileview-tile-content, div.ms-tileview-tile-detailsBox {
width: 100px !important;
height: 100px !important;
background-color: rgb(63,68,68);
-webkit-border-radius: 7px;
-moz-border-radius: 7px;
border-radius: 7px;

}

/* tile background image dimensions */
div.ms-tileview-tile-content > a > div > img {
max-width: 50%;
width: 50% !important;
position: relative;
top:9px;
margin:auto;
}

/* title and description text */
ul.ms-tileview-tile-detailsListMedium {
height: 100px;
font-size: 11px;
line-height: 100%;
text-align: center;
margin:auto;
}

/* description text class */
li.ms-tileview-tile-descriptionMedium {
padding-top: 10px;
font-size: 11px;
}

/* title text when description not shown */
div.ms-tileview-tile-titleTextMediumCollapsed {
background-color: rgba(0, 0, 0, 0.6);
width: 86px;
height: 29px;
position: absolute;
top: -33px;
left: 0px;
padding: 4px 7px 0px;
font-size: 11px;
line-height: 13px;
}
.ms-tileview-tile-titleMedium,
.ms-tileview-tile-titleMediumCollapsed,
.ms-tileview-tile-titleMediumExpanded,
.ms-tileview-tile-titleSmall,
.ms-tileview-tile-titleSmallCollapsed,
.ms-tileview-tile-titleSmallExpanded,
.ms-tileview-tile-descriptionMedium {
display: block;
text-align: center;
}
</style>