.article-container article {
    width: 640px;
    margin: 30px auto;
    padding: 30px;
    border: 1px solid #eee;
    background-color: #f9f9f9;
}
.article-container article:after {
	content: ''; display: block; clear: both;
}

.article-container article > h2 {
	margin: 0 0 15px;
	font-size: 15px;
}

.article-container article .social .kakao-btn {
    width: 100%;
    background-color: #fee500;
}

/*.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;
}

@media screen and (max-width: 702px) {
	.article-container article {
		width: calc(100% - 80px); margin: 30px 10px;
	}
}

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