<a href="javascript:" class="btn btn_plus" role="button" title="增加"></a>
<input class="inputNum" value="1" size="1">
<a href="javascript:" class="btn btn_minus" role="button" title="减少"></a>
.inputNum {
    vertical-align: middle;
    height: 22px;
    border: 1px solid #d0d0d0;
    text-align: center;
}
.btn {
    display: inline-block;
    vertical-align: middle;
    background: #f0f0f0 no-repeat center;
    border: 1px solid #d0d0d0;
    width: 24px;
    height: 24px;
    border-radius: 2px;
    box-shadow: 0 1px rgba(100, 100, 100, .1);
    color: #666;
    transition: color .2s, background-color .2s;
}
.btn:active {
    box-shadow: inset 0 1px rgba(100, 100, 100, .1);
}
.btn:hover {
    background-color: #e9e9e9;
    color: #333;
}
.btn_plus {
    background-image: linear-gradient(to top, currentColor, currentColor), linear-gradient(to top, currentColor, currentColor);
    background-size: 10px 2px, 2px 10px;
}
.btn_minus {
    background-image: linear-gradient(to top, currentColor, currentColor);
    background-size: 10px 2px;
}