http://www.reedyrace.com/ae/pillchart-RC/index.html
The above is a fully functional page. Click on a black button in tab C Mount, then any button on tab D Mount, then tab Results for results. Don’t worry what it is about 
My question: How do I get rid of the gray around the black buttons? I simply cannot find the area in the css page where that coloring occurs. I want the surrounding color to replace it.
Portion of CSS:
.container {
display: block;
margin-left: auto;
margin-right: auto;
padding-right: .5em;
max-width: 600px;
}
.rowgr {
display: flex;
flex-direction: row;
align-items: center;
width: 100%;
border: 0;
padding: .2em .2em;
}
.rowflleft {
display: flex;
flex-direction: column;
justify-content: center;
margin-right: auto;
}
.clearfix::after {
content: '';
display: block;
clear: both;
}
.buttonSetup { width: 7em; }
/* Inserts Grid */
.grid-container {
display: grid;
grid-template-columns: 4em 4em 4em;
grid-template-rows: 4em 4em 4em;
}
.grid-divc, .grid-divd {
text-align:center;
}
/* Results Grid */
.gridResultsFinal {
display: grid;
grid-template-columns: 33% 33% 33%; // 12% 19% 25% 22% 22%;
grid-template-rows: 2em 2em 3.5em; // 2em;
text-align:center;
}
.grid-div-res, .grid-div-resh {
border: 1px solid gray;
background-color: white;
}
.grid-div-resh {
font-size: 1em;
background-color: #ddd;
padding: .1em .1em;
}
.grid-div-res {
font-size: 1.3em;
}
/* Inserts buttons */
img {
width: 40px;
height: 40px;
border: none;
}
.buttonSetup { /* nav buttons */
width: 7em;
background-color: #ddd;
border-radius: 8px;
border: #ccc solid 1px;
padding: 0;
height: 2em;
-webkit-appearance:normal;
text-align: center;
margin-bottom: 1em;
color: black;
}
/* TABS https://medium.com/allenhwkim/how-to-build-tabs-only-with-css-844718d7de2f */
input { display: none; } /* hide radio buttons */
input + label { display: inline-block } /* show labels in line */
input ~ .tab { display: none } /* hide contents */
/* show contents only for selected tab */
#tab1:checked ~ .tab.content1,
#tab2:checked ~ .tab.content2,
#tab3:checked ~ .tab.content3 { display: block; }
input + label { /* tab */
border: 1px solid #999;
width: 6em;
background: #EEE;
padding: .5em .5em;
position: relative;
top: 1px;
text-align: center;
}
input:checked + label { /* white background for selected tab */
background: #FFF;
border-bottom: 1px solid transparent;
}
input ~ .tab { /* grey line between tab and contents */
border-top: 1px solid #999;
}
/* Rotate the Insert Images */
.item { /* holds C and D images at top */
text-align:center;
height: auto;
}
.cMountLeftImg, #cResultsLeft, .dMountLeftImg, #dResultsLeft {
width: 200px;
height: auto;
text-align: center;
}
HTML for C Mount:
<form id="form_pillchart">
<div class="rowgr pad2">
<div class="rowflleft">
<p><strong>For the RC8B3.2, B3.2e and RC8T3.2, T3.2e.</strong>
<br>Choose your C and D mount inserts and this will calculate your settings.</p>
</div>
</div>
<input type="radio" name="tabs" id="tab1" checked />
<label for="tab1" class="fontstack">C Mount</label>
<input type="radio" name="tabs" id="tab2" />
<label for="tab2" class="fontstack">D Mount</label>
<input type="radio" name="tabs" id="tab3" />
<label for="tab3" class="fontstack">Results</label>
<div class="tab content1">
<div style="background-color: #EBF5FB">
<p class="cen" style="padding-top: .5em;"><strong>C Mount</strong><span id="cInsertChosen" class="cen"></span></p>
<div class="mounts-container" id="cMountLeft"><span class="item"><img src="images/cmount_blank.png" alt="insert not chosen" class="cMountLeftImg"></span></div>
</div>
<div class="rowgr" style="background-color: #EBF5FB">
<div class="cen fontstack">
<p class="selectC">Select your left insert below.</p>
<div class="grid-container">
<div class="grid-divc" id="ca1"><button class="clearfix" value="1,1,1,-1,1-corner"><img title="1,1,1,-1" alt="1,1,1,-1" src="images/1-cornerb.png"></button></div>
<div class="grid-divc" id="ca3"><button class="clearfix"value="0,1,0,1,1-center"><img title="0,1,0,1" alt="0,1,0,1" src="images/1-centerb.png"></button></div>
<div class="grid-divc" id="ca5"><button class="clearfix"value="-1,1,1,1,1-corner"><img title="-1,1,1,1" alt="-1,1,1,1" src="images/1-cornerb.png" class="buttonC transform1"></button></div>
<div class="grid-divc" id="cc1"><button class="clearfix"value="1,0,-1,0,1-center"><img title="1,0,-1,0" alt="1,0,-1,0" src="images/1-centerb.png" class="buttonC transform2"></button></div>
<div class="grid-divc" id="cc3"><button class="clearfix"value="0,0,0,0,center-center"><img title="0,0,0,0" alt="0,0,0,0" src="images/center-centerb.png"></button></div>
<div class="grid-divc" id="cc5"><button class="clearfix"value="-1,0,1,0,1-center"><img title="-1,0,1,0" alt="-1,0,1,0" src="images/1-centerb.png" class="buttonC transform1"></button></div>
<div class="grid-divc" id="ce1"><button class="clearfix"value="1,-1,-1,-1,1-corner"><img title="1,-1,-1,-1" alt="1,-1,-1,-1" src="images/1-cornerb.png" class="buttonC transform2"></button></div>
<div class="grid-divc" id="ce3"><button class="clearfix"value="0,-1,0,-1,1-center"><img title="0,-1,0,-1" alt="0,-1,0,-1" src="images/1-centerb.png" class="buttonC transform3"></button></div>
<div class="grid-divc" id="ce5"><button class="clearfix"value="-1,-1,-1,1,1-corner"><img title="-1,-1,-1,1" alt="-1,-1,-1,1" src="images/1-cornerb.png" class="buttonC transform3"></button></div>
</div>
</div>
</div>
</div> <!-- tab group -->
<div class="tab content2">
<div style="background-color: #FBEEE6">
<p class="cen" style="padding-top: .5em;"><strong>D Mount</strong><span id="dInsertChosen" class="cen"></span></p>
<div class="mounts-container" id="dMountLeft"><span class="item"><img src="images/dmount_blank.png" alt="insert not chosen" class="dMountLeftImg"></span></div>
</div>