如何设计具有自定义颜色和底部边框等的微调器？

<div class="custom-spinner">
  <input type="text" class="value-input">
  <button class="increase-btn">+</button>
  <button class="decrease-btn">-</button>
</div>

.custom-spinner {
  display: inline-block;
  border: 1px solid #ccc;
  border-radius: 4px;
  padding: 4px;
}

.value-input {
  width: 50px;
  text-align: center;
}

.increase-btn,
.decrease-btn {
  width: 20px;
  height: 20px;
  background-color: #ccc;
  border: none;
  color: #fff;
  font-weight: bold;
  cursor: pointer;
}

.increase-btn:hover,
.decrease-btn:hover {
  background-color: #999;
}

// 获取微调器元素
const spinner = document.querySelector('.custom-spinner');
const input = spinner.querySelector('.value-input');
const increaseBtn = spinner.querySelector('.increase-btn');
const decreaseBtn = spinner.querySelector('.decrease-btn');

// 设置初始值和步长
let value = 0;
const step = 1;

// 增加数值的函数
function increaseValue() {
  value += step;
  input.value = value;
}

// 减少数值的函数
function decreaseValue() {
  value -= step;
  input.value = value;
}

// 绑定按钮点击事件
increaseBtn.addEventListener('click', increaseValue);
decreaseBtn.addEventListener('click', decreaseValue);