menduner-uniapp/custom-tab-bar/index.wxss

.tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 60px;
  background: white;
  display: flex;
  padding-bottom: env(safe-area-inset-bottom);
  border-radius: 20px 20px 0 0;
  box-shadow: 0px 8px 20px 0px rgba(0,0,0,.5);
  z-index: 0;
}

.tab-bar-border {
  background-color: rgba(0, 0, 0, 0.33);
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 1px;
  transform: scaleY(0.5);
}

.tab-bar-item {
  flex: 1;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  position: relative;
}

.tab-bar-item.center {
  margin-top: -20px;
}
.tab-bar-item.center image {
  width: 56px;
  height: 56px;
  z-index: 3;
  border-radius: 50%;
}
.tab-bar-item.center::before {
  content: '';
  width: 64px;
  height: 32px;
  position: absolute;
  left: 50%;
  top: 0;
  transform: translate(-50%, 0px);
  background: #FFF;
  border-radius: 180px 180px 0 0 ;
  box-shadow: 0px 8px 20px 0px rgba(0,0,0,.5);
  /* clip-path: inset(0 0 66.66% 0); 裁剪三分之一高度 */
}
.tab-bar-item.center::after {
  content: '';
  width: 100px;
  height: 40px;
  position: absolute;
  left: 50%;
  top: 20px;
  background: #FFF;
  transform: translate(-50%, 0px);
}
.tab-bar-item image {
  width: 27px;
  height: 27px;
}

.tab-bar-item view {
  font-size: 12px;
}