@media (max-width: 800px) {
    .alert {
        width: 90%;
    }
    .form-control {
        font-size: 1.2rem;
        padding: 0.5rem 1rem;
    }
    .btn-close {
        width: 1.5em;
        height: 1.5em;
    }
    .invalid-feedback,
    .valid-feedback {
        font-size: 1rem;
    }
}


/* input & validation */
:root {
    --form-feedback-valid-color: #198754;
    --form-feedback-invalid-color: #dc3545;
}
.form-control {
    display: block;
    width: 100%;
    padding: 0.375rem 0.75rem;
    font-size: 1rem;
    line-height: 1.5;
    color: #495057;
    background-color: #fff;
    background-clip: padding-box;
    border: 1px solid #ced4da;
    border-radius: 0.25rem;
    transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
    box-sizing: border-box;
}
.form-control.is-valid,
#loginArea .loginInner .class_id.is-valid,
#loginArea .loginInner .class_pwd.is-valid {
    border-color: #198754;
    padding-right: calc(1.5em + 0.75rem);
    background-repeat: no-repeat;
    background-position: right calc(0.375em + 0.1875rem) center;
    background-size: calc(0.75em + 0.375rem) calc(0.75em + 0.375rem);
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 8 8'%3e%3cpath fill='%23198754' d='M2.3 6.73L.6 4.53c-.4-1.04.46-1.4 1.1-.8l1.1 1.4 3.4-3.8c.6-.63 1.6-.27 1.2.7l-4 4.6c-.43.5-.8.4-1.1.1z'/%3e%3c/svg%3e");
}
.form-control.is-invalid,
#loginArea .loginInner .class_id.is-invalid,
#loginArea .loginInner .class_pwd.is-invalid {
    border-color: #dc3545;
    padding-right: calc(1.5em + 0.75rem);
    background-repeat: no-repeat;
    background-position: right calc(0.375em + 0.1875rem) center;
    background-size: calc(0.75em + 0.375rem) calc(0.75em + 0.375rem);
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 12' width='12' height='12' fill='none' stroke='%23dc3545'%3e%3ccircle cx='6' cy='6' r='4.5'/%3e%3cpath stroke-linejoin='round' d='M5.8 3.6h.4L6 6.5z'/%3e%3ccircle cx='6' cy='8.2' r='.6' fill='%23dc3545' stroke='none'/%3e%3c/svg%3e")
}
#loginArea .loginInner .class_id.is-invalid,
#loginArea .loginInner .class_pwd.is-invalid {
    border: 1px solid #dc3545;
}
.form-control:hover {
    border-color: #80bdff;
}
.form-control:focus {
    color: #495057;
    background-color: #fff;
    border-color: #80bdff;
    outline: 0;
    box-shadow: 0 0 0 0.01rem rgba(0, 123, 255, 0.25);
}
.invalid-feedback,
.valid-feedback {
    display: none;
    width: 100%;
    margin-top: 0.25rem;
    font-size: 80%;
    color: #dc3545;
}
.valid-feedback {
    color: #28a745;
}


/* alert */
.alert-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: none;
    z-index: 1000;
}
.alert {
    position: absolute;
    top: 25%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1001;
    width: 300px;
    padding: 1rem 1rem;
    margin: 0 auto 1rem;
    border: 1px solid transparent;
    border-radius: .25rem;
    display: flex;
    align-items: center;
    transition: opacity 0.15s linear;
}
.alert-primary {
    background-color: #cce5ff;
    border-color: #b8daff;
    color: #004085;
}
.alert-success {
    background-color: #d4edda;
    border-color: #c3e6cb;
    color: #155724;
}
.alert-warning {
    background-color: #ffeeba;
    border-color: #ffeeba;
    color: #856404;
}
.alert-danger {
    background-color: #f8d7da;
    border-color: #f5c6cb;
    color: #721c24;
}
.alert .bi {
    margin-right: 15px;
}
.alert-primary .bi {
    fill: #004085;
}
.alert-success .bi {
    fill: #155724;
}
.alert-warning .bi {
    fill: #856404;
}
.alert-danger .bi {
    fill: #721c24;
}
.btn-close {
    box-sizing: content-box;
    width: 1em;
    height: 1em;
    padding: 0.25em 0.25em;
    color: #000;
    background: transparent url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='%23000'%3e%3cpath d='M.293.293a1 1 0 011.414 0L8 6.586 14.293.293a1 1 0 111.414 1.414L9.414 8l6.293 6.293a1 1 0 01-1.414 1.414L8 9.414l-6.293 6.293a1 1 0 01-1.414-1.414L6.586 8 .293 1.707a1 1 0 010-1.414z'/%3e%3c/svg%3e") center/1em auto no-repeat;
    border: 0;
    border-radius: 0.25rem;
    opacity: .5;
    cursor: pointer;
    margin-left: auto;
}
.btn-close:hover {
    opacity: 0.8;
}


/* margin */
.mx-2 {
    margin-right: 0.5rem;
    margin-left: 0.5rem;
}
.my-2 {
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
}
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-1 { margin-left: 0.25rem; }
.ml-2 { margin-left: 0.5rem; }
.ml-3 { margin-left: 1rem; }
.ml-4 { margin-left: 1.5rem; }
.mb-1 { margin-right: 0.25rem; }
.mr-2 { margin-right: 0.5rem; }
.mr-3 { margin-right: 1rem; }
.mr-4 { margin-right: 1.5rem; }


/* card */
.card {
    border: 1px solid rgba(0,0,0,0.125);
    border-radius: 0.25rem;
    overflow: hidden;
    position: relative;
    background-color: #fff;
    box-shadow: 0 0.5rem 1rem rgba(0,0,0,0.15);
}
.card-header {
    padding: 0.75rem 1.25rem;
    background-color: rgba(0,0,0,0.03);
    border-bottom: 1px solid rgba(0,0,0,0.125);
    font-weight: bold;
}
.card-body {
    padding: 1.25rem;
}


/* button */
/* 기본 버튼 스타일 */
.btn {
    display: inline-block;
    font-weight: 400;
    color: #212529;
    text-align: center;
    vertical-align: middle;
    cursor: pointer;
    user-select: none;
    background-color: transparent;
    border: 1px solid transparent;
    padding: 0.375rem 0.75rem;
    font-size: 1rem;
    line-height: 1.5;
    border-radius: 0.25rem;
    transition: color 0.15s ease-in-out, background-color 0.15s ease-in-out, border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
}

.btn:hover {
    color: #212529;
    text-decoration: none;
}

.btn:focus, .btn.focus {
    outline: 0;
    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
}

/* btn-primary 스타일 */
.btn-primary {
    color: #fff;
    background-color: #007bff;
    border-color: #007bff;
}

.btn-primary:hover {
    color: #fff;
    background-color: #0056b3;
    border-color: #004d99;
}

.btn-primary:focus, .btn-primary.focus {
    box-shadow: 0 0 0 0.2rem rgba(38, 143, 255, 0.5);
}

.btn-primary:active, .btn-primary.active {
    color: #fff;
    background-color: #0056b3;
    background-image: none;
    border-color: #004d99;
}

.swal-button.btn-primary {
    color: #fff;
    background-color: #007bff;
    border-color: #007bff;
}

.swal-button.btn-primary:hover {
    color: #fff;
    background-color: #0056b3;
    border-color: #004d99;
}

.swal-button.btn-primary:focus,
.swal-button.btn-primary.focus {
    box-shadow: 0 0 0 0.2rem rgba(38, 143, 255, 0.5);
}

.swal-button.btn-primary:active,
.swal-button.btn-primary.active {
    color: #fff;
    background-color: #0056b3;
    background-image: none;
    border-color: #004d99;
}