Making up down arrow of HTML's input number much bigger and cleaner

you can wrap a input in and element and style it

div {
  display: inline-block;
  position: Relative;
  border: 2px solid grey;
  border-radius: 10px;
  overflow: hidden;
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  -khtml-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}
div:before,
div:after {
  background: white;
  right: 0px;
  width: 30px;
  height: 20%;
  position: absolute;
  pointer-events: none;
}
div:before {
  content: '';
  bottom: 50%;
  background: url(http://cdn.flaticon.com/png/256/22205.png) no-repeat white;
  background-size: 20px;
  background-position: center;
}
div:after {
  content: '';
  top: 50%;
  background: url(http://cdn.flaticon.com/png/256/22205.png) no-repeat white;
  background-size: 20px;
  transform: rotate(180deg);
  background-position: center;
}
input {
  height: 80PX;
  font-size: 50px;
  outline: 0;
  border: 0;
}
<div>
  <input type="number" value="10" />
</div>


well, to achieve that you have to play with pseudo elements and some CSS3 tricks.

to create triangle https://css-tricks.com/snippets/css/css-triangle/

to manipulate input number spinners

input[type=number]::-webkit-inner-spin-button {
    /* your code*/
}

here is the example.

input {
	  color: #777;
	  width: 2em;
	  font-size: 2em;
	  border-radius: 10px;
	  border: 2px solid #ccc;
	  padding: 5px;
	  padding-left: 10px;
	}
	input[type=number]::-webkit-inner-spin-button {
	  -webkit-appearance: none;
	  cursor: pointer;
	  display: block;
	  width: 10px;
	  text-align: center;
	  position: relative;
	  background: transparent;
	}
	input[type=number]::-webkit-inner-spin-button::before,
	input[type=number]::-webkit-inner-spin-button::after {
	  content: "";
	  position: absolute;
	  right: 0;
	  width: 0;
	  height: 0;
	  border-left: 7px solid transparent;
	  border-right: 7px solid transparent;
	  border-bottom: 10px solid #777;
	}
	input[type=number]::-webkit-inner-spin-button::before {
	  top: 7px;
	}
	input[type=number]::-webkit-inner-spin-button::after {
	  bottom: 7px;
	  transform: rotate(180deg);
	}
<input type="number" value="1">