/* 先頭にアイコン */
.test_button .button_head_space::before {
    content: "\f11d";
}
/* 末尾にアイコン */
.test_button .button_end_space::before {
    content: "\f024";
}
/* 共通指定 */
.test_button .button_head_space,
.test_button .button_end_space {
    display: inline-block;
    font-family: FontAwesome;
    font-synthesis: weight style;
    line-height: 1;
}