body {
    margin: 0;
    overflow-x: hidden;
    background: black;
    font-family: 'Consolas', monospace;
    color: white;
}

/* 星の背景 */
#starfield {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
}

/* 中央コンテンツ */
#content {
    text-align: center;
    padding-top: 10vh;
}

/* ★ 大きなロゴ */
.big-logo {
    width: 180px;        /* 大きさは自由に調整可能 */
    height: auto;
    display: block;
    margin: 0 auto 25px auto;

    /* 発光エフェクト（宇宙感UP） */
    filter: drop-shadow(0 0 15px rgba(0, 150, 255, 0.7));
}

.title {
    font-size: 4rem;
    letter-spacing: 4px;
    opacity: 0;
    animation: fadeIn 2s forwards;
}

.subtitle {
    font-size: 1.5rem;
    opacity: 0;
    animation: fadeIn 3s forwards;
}

.version {
    margin-top: 10px;
    font-size: 1.2rem;
    color: #0af;
}

#start-btn {
    margin-top: 40px;
    padding: 15px 40px;
    font-size: 1.2rem;
    background: #0af;
    border: none;
    color: white;
    cursor: pointer;
    border-radius: 8px;
    transition: 0.3s;
}

#start-btn:hover {
    background: #0cf;
    transform: scale(1.05);
}

.section {
    width: 70%;
    margin: 80px auto;
    text-align: left;
    opacity: 0;
    animation: fadeInUp 1.5s forwards;
}

.section h2 {
    color: #0af;
}

/* アニメーション */
@keyframes fadeIn {
    to { opacity: 1; }
}

@keyframes fadeInUp {
    from { transform: translateY(40px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}