@import url("https://fonts.googleapis.com/css2?family=Dela+Gothic+One&display=swap");

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    width: 100%;
    overflow: hidden;
}

body {
    background: radial-gradient(ellipse at bottom, #022227 0%, #000000 100%);
    font-family: "Dela Gothic One", sans-serif;
    text-align: center;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

/* ナビゲーションバーのスタイル */
#mainnav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #333; /* 背景色はお好みで */
    color: white; /* テキストの色 */
    padding: 10px 0; /* 上下のパディング */
    text-align: center; /* 中央寄せ */
    z-index: 1000; /* 他の要素の上に表示 */
    font-size: 24px; /* PCとスマホで見やすいサイズに調整 */
}

/* ナビゲーションリンクのスタイル */
#mainnav a {
    color: white; /* リンクの色 */
    text-decoration: none; /* 下線を消す */
    margin: 0 15px; /* リンクの左右のマージン */
    font-family: 'Dela Gothic One', sans-serif; /* フォントファミリー */
}

/* ホバー時のスタイル */
#mainnav a:hover {
    text-decoration: underline; /* ホバー時の下線 */
}

.context {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: #fff;
    padding: 20px;
    max-width: 90%;
    box-sizing: border-box;
    z-index: 10; /* circlesの上に表示 */
}

.context h1, .context h2, .context p {
    font-family: "Dela Gothic One", sans-serif;
    margin-bottom: 20px;
}

.context h1 {
    margin-top: 80px;
    font-size: 34px;
    font-weight: 100;
}

.context h2 {
    font-size: 42px;
    font-weight: 100;
}

.context p {
    font-size: 28px;
}

.area {
    background: #5f5858;
    background: -webkit-linear-gradient(to left, #969696, #5f5858);
    width: 100%;
    height: 100vh;
    position: relative;
    overflow: hidden; /* Ensure circles stay within the area */
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1;
}

.circles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: 0; /* Ensure circles are below other content */
}

.circles li {
    position: absolute;
    display: block;
    list-style: none;
    width: 20px;
    height: 20px;
    background: rgba(255, 255, 255, 0.2);
    animation: animate 25s linear infinite;
    bottom: -150px;
    z-index: -1;
}

.circles li:nth-child(1) {
    left: 25%;
    width: 80px;
    height: 80px;
    animation-delay: 0s;
}

.circles li:nth-child(2) {
    left: 10%;
    width: 20px;
    height: 20px;
    animation-delay: 2s;
    animation-duration: 12s;
}

.circles li:nth-child(3) {
    left: 70%;
    width: 20px;
    height: 20px;
    animation-delay: 4s;
}

.circles li:nth-child(4) {
    left: 40%;
    width: 60px;
    height: 60px;
    animation-delay: 0s;
    animation-duration: 18s;
}

.circles li:nth-child(5) {
    left: 65%;
    width: 20px;
    height: 20px;
    animation-delay: 0s;
}

.circles li:nth-child(6) {
    left: 75%;
    width: 110px;
    height: 110px;
    animation-delay: 3s;
}

.circles li:nth-child(7) {
    left: 35%;
    width: 150px;
    height: 150px;
    animation-delay: 7s;
}

.circles li:nth-child(8) {
    left: 50%;
    width: 25px;
    height: 25px;
    animation-delay: 15s;
    animation-duration: 45s;
}

.circles li:nth-child(9) {
    left: 20%;
    width: 15px;
    height: 15px;
    animation-delay: 2s;
    animation-duration: 35s;
}

.circles li:nth-child(10) {
    left: 85%;
    width: 150px;
    height: 150px;
    animation-delay: 0s;
    animation-duration: 11s;
}

@keyframes animate {
    0% {
        transform: translateY(0) rotate(0deg);
        opacity: 1;
        border-radius: 0;
    }
    100% {
        transform: translateY(-1000px) rotate(720deg);
        opacity: 0;
        border-radius: 50%;
    }
}

/* スマートフォン用のスタイル調整 */
@media screen and (max-width: 768px) {
    #mainnav {
        font-size: 18px;
    }

    .context h1 {
        font-size: 28px;
    }

    .context h2 {
        font-size: 26px;
    }

    .context p {
        font-size: 22px;
    }
}