html, body {
    height: 100%; /* ページ全体を占める */
    margin: 0;
    padding: 0;
}
body {
    display: flex;
    flex-direction: column;
    min-height: 100vh; /* ビューポート全体を埋める */
}
/* content */
.content {
    padding-right: 15px;
    padding-left: 15px;
    margin-right: auto;
    margin-left: auto;
}
.sectionBg {
    padding: 40px 0;
}
@media (min-width: 576px) {
    .content {
        max-width: 540px;
        width: 100%;
    }
}

@media (min-width: 768px) {
    .content {
        max-width: 720px;
    }
    .sectionBg {
        padding: 80px 0;
    }
}

@media (min-width: 992px) {
    .content {
        max-width: 960px;
    }
}

@media (min-width: 1200px) {
    .content {
        max-width: 1140px;
    }
}
main {
    flex-grow: 1;
}

/* common */
header {
    position: sticky;
    top: 0;
    position: relative;
}
header,footer {
    background-color: #0ABCD3;
    padding: 10px;
    color: white;
    display: block;
}
header a {
    display: flex;
    justify-content: flex-end;
}
header img,
footer img {
    height: 50px;
}
footer .footer-wrap {
    text-align: center;
}
footer .footer-wrap p {
    margin: 0;
}
/* form area */
.form-wrap h1 {
    text-align: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    position: relative;
}
.form-wrap h1::before {
    position: absolute;
    content: "";
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    -webkit-transform: translateX(-50%);
    -ms-transform: translateX(-50%);
    background-color: #0ABCD3;
    width: 100px;
    height: 3px;
}
.form-wrap .form-box {
    text-align: center;
}