@font-face {
    font-family: "Noto Sans JP";
    src:
        local("Noto Sans JP Regular"),
        local("NotoSansJP-Regular"),
        url(/NotoSansJP-Regular.woff2) format("woff2");
    font-style: normal;
    font-display: swap;
}
body {
    background: linear-gradient(45deg, #ff0000 0%, #FFA500 16%, #FFFF00 32%, #00FF00 48%, #00FFFF 64%, #0000FF 80%, #8000FF 100%);
    font-family: "Noto Sans JP";
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-size: cover;
    margin: 0;
    padding: 20px;
}
.ren-box {
    opacity: 1;
    padding: 30px;
    max-width: 1000px;
    border-radius: 20px;
    margin: 50px 0;
    background-color: #bec;
}
p,
a,
ul,
li,
hr {
    color: #0080c0;
}
h1,
h2,
h3,
h4,
h5,
h6 {
    color: #0080c0;
    margin-top: 20px;
    margin-bottom: 10px;
}
button {
    border: none;
    background-color: #48b;
    border-radius: 5px;
    padding: 10px;
    cursor: pointer;
}
.upbar {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
}