.article-container article {
	width: 640px; margin: 30px auto; padding: 30px;
	border: 1px solid #eee; background-color: #f9f9f9;
}

.article-container article .form-group {
	margin: 30px 0;
}
.article-container article .form-group input {
	background-color: transparent;
	border: 1px solid #ccc; outline: none;
}

.article-container article .button-group:after {
	content: ''; display: block; clear: both;
}
.article-container article .button-group {
	margin: 0 0 15px;
}
.article-container article .button-group .btn {
	display: block; float: left; width: calc(50% - 5px);
	background-color: #000; color: #fff;
}
.article-container article .button-group .btn.btn-login {
	margin-right: 5px;
}
.article-container article .button-group .btn.btn-join {
	margin-left: 5px;
}

.article-container article .social {
	padding: 15px 0 0 0; border-top: 1px solid #ccc;
}
.article-container article .social .kakao-btn {
	width: 100%; background-color: #fee500; 
}


@media screen and (max-width: 640px) {
	.article-container article {
		width: calc(100% - 40px); padding: 10px; margin: 30px 10px;
	}
}