.m_header {
    position: fixed;
    width: 100%;
    height: 50px;;
    top: 0;
    z-index: 100;
    background-color: #ffffff;
    box-sizing: border-box;
}

.m_header span {
    background-color: #a0a0a0;
}

.m_header .logo {
    height: 30px;
}

.m_header .top_bar{
    display: flex;
    justify-content: space-between;
    align-items: center;
}