.button_back {
    position: relative;
    background: #000;
    color: #fff;
    border: none;
    padding: 10px 18px 10px 36px;
    border-radius: 999px;
    font-size: 14px;
    cursor: pointer;
    transition: .2s;
}

.button_back::before {
    content: "";
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    border-top: 6px solid transparent;
    border-bottom: 6px solid transparent;
    border-right: 8px solid #fff;
}