.s_type {
    border: none;
    border-radius: 5px;
    background-color: #f3f3f3;
    padding: 7px 0;
    color: #606266;
    margin: 5px 2.5% 5px 0;
    width: 30%;
    position: relative;
}

.selecd {
    background-color: #ebf3ff;
    color: #5999fc;
}

.select {
    background-color: #ebf3ff;
    color: #5999fc;
}

.select:before {
    content: '';
    position: absolute;
    right: 0;
    bottom: 0;
    border: 9px solid #5999fc;
    border-top-color: transparent;
    border-left-color: transparent;
}

<button class="s_type">全部</button>
<button class="s_type">2020年夏季</button>

$(’.s_type’).on(‘click’,function(){
$(this).toggleClass(‘select’);
});

.select {
		position: relative;
		width:81px;
		height:93px;
		margin: 0 auto;
		text-align: center;
		line-height: 93px;
		color: #4ABE84;
		background-color: #fff;
		box-shadow:0px 2px 7px 0px rgba(85,110,97,0.35);
		border-radius:7px;
		border:1px solid rgba(74,190,132,1);
	}
	.select:before {
		content: '';
		position: absolute;
		right: 0;
		bottom: 0;
		border: 17px solid #4ABE84;
		border-top-color: transparent;
		border-left-color: transparent;
	}
	.select:after {
		content: '';
		width: 5px;
		height: 12px;
		position: absolute;
		right: 6px;
		bottom: 6px;
		border: 2px solid #fff;
		border-top-color: transparent;
		border-left-color: transparent;
		transform: rotate(45deg);
	}

<div class="select">测试</div>