.tpbox i{position: relative;}

.tpbox i span{position: absolute;top: 0;bottom: 0;left: 0;right: 0;text-align: center;display: table;height: 100%}
.tpbox i span em{display: table-cell;vertical-align: middle;height: 100%;padding: 0 20px;color: #fff;font-size: 16px;font-weight: bold;}