HTML5 slider bar's thumb can't cover the track - css

Question

I made a slider bar with html5 & css, like this.
function showValue(value) {
document.getElementById("range").innerHTML = value;
}
.c-zoombar {
-webkit-appearance: none;
background: none;
outline: none;
overflow: hidden;
width: 200px;
height: 20px;
}
.c-zoombar::-webkit-slider-thumb {
-webkit-appearance: none;
background: #5e6fd9;
border: 1px solid #fff;
border-radius: 50%;
height: 12px;
position: relative;
top: -5.5px;
transition: .2s;
width: 12px;
}
.c-zoombar::-webkit-slider-runnable-track {
background: transparent;
border: 1px solid #000;
border-radius: 2px;
cursor: pointer;
height: 3px;
width: 100%;
}
.c-zoombar:active::-webkit-slider-thumb {
height: 16px;
top: -8px;
width: 16px;
}
.c-zoombar::-webkit-slider-thumb:hover {
height: 16px;
top: -8px;
width: 16px;
}
<div>
<input type="range" value="0" class="c-zoombar" onInput="showValue(this.value)" />
</div>
<div>
<span id="range">0</span>
</div>
However, when I scroll the thumb to the most right/left, the thumb can't totally cover the track, as you can see in the following image.
What should I modify to make the thumb be able to cover the track when scrolling to the most right/left? Thank you.

Answer 1

I found the transform: scale() could do the part of trick (also scale transitioned more smoothly then width/height). is that 12px size is mandatory?
function showValue(value) {
document.getElementById("range").innerHTML = value;
}
.c-zoombar {
-webkit-appearance: none;
background: none;
outline: none;
overflow: visible;
width: 200px;
height: 20px;
}
.c-zoombar::-webkit-slider-thumb {
-webkit-appearance: none;
background: #5e6fd9;
border: 1px solid #fff;
border-radius: 50%;
height: 12px;
position: relative;
top: -5.5px;
transition: .2s;
width: 12px;
transform: scale(1.33);
}
.c-zoombar::-webkit-slider-runnable-track {
background: transparent;
border: 1px solid #000;
border-radius: 2px;
cursor: pointer;
height: 3px;
width: 100%;
}
.c-zoombar:active::-webkit-slider-thumb,
.c-zoombar::-webkit-slider-thumb:hover {
transform: scale(1.66);
}
<div class='wrap'>
<input type="range" value="0" class="c-zoombar" onInput="showValue(this.value)" />
</div>
<div>
<span id="range">0</span>
</div>