#ss_header {
    width: 740px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 15px;
    margin-bottom: 15px;
    display: flex;
    justify-content: space-between;
}

.sign_up_box {
    display: flex;
    align-items: center;
}

#ss_header p {
    margin: 10px 10px 0;
    vertical-align: middle;
    font-size: 1.1em;
}