/*** for PC Browser ***/
@media (min-width:401px)
{
.flex_block
{
    display: flex;
}

.flex_box
{
    width: 49%;
    margin-left: auto;
    margin-right: auto;
}
}


/*** for Smart Phone ***/
@media (max-width:400px)
{
.flex_block
{
    display: flex;
    flex-wrap: wrap;
}

.flex_box
{
    width: 100%;
}
}