.bt_t{
	box-sizing: border-box;
	width: 700px;
	padding: 10px;
	margin:20px auto 0;
	border: 1px solid rgba(0, 0, 0, 0.3);
	text-align: left;
}

@media screen and (max-width: 750px) {
    .bt_t {
        width: auto;
		margin:20px 15px 0;
    }
}