:root {
            --bg-color: #0f172a;
            --card-bg: rgba(30, 41, 59, 0.7);
            --accent: #00e5ff;
            --panel-border: rgba(255, 255, 255, 0.1);
            --text-main: #f8fafc;
            --text-sub: #94a3b8;
        }

        body {
            margin: 0;
            padding: 0;
            font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--bg-color);
            background-image: 
                radial-gradient(circle at 20% 30%, rgba(0, 229, 255, 0.05) 0%, transparent 40%),
                radial-gradient(circle at 80% 70%, rgba(0, 229, 255, 0.05) 0%, transparent 40%);
            color: var(--text-main);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        .header {
            text-align: center;
            padding: 60px 20px 40px;
        }

        h1 {
            font-size: 3rem;
            letter-spacing: 0.2em;
            margin: 0;
            background: linear-gradient(to bottom, #fff 40%, var(--accent));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            text-shadow: 0 0 30px rgba(0, 229, 255, 0.3);
        }

        .subtitle {
            font-size: 0.9rem;
            letter-spacing: 0.4em;
            color: var(--accent);
            margin-top: 10px;
            opacity: 0.8;
        }

        .grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
            gap: 25px;
            width: 90%;
            max-width: 1200px; /* カード3枚に対応するため少し拡張 */
            padding: 20px;
        }

        .card {
            background: var(--card-bg);
            border: 1px solid var(--panel-border);
            border-radius: 16px;
            padding: 25px;
            display: flex;
            flex-direction: row;
            align-items: center;
            gap: 20px;
            text-decoration: none;
            color: inherit;
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            backdrop-filter: blur(12px);
            position: relative;
            overflow: hidden;
        }

        .card:hover {
            transform: translateY(-5px);
            border-color: var(--accent);
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5), 0 0 20px rgba(0, 229, 255, 0.1);
        }

        .icon-box {
            width: 70px;
            height: 70px;
            min-width: 70px;
            background: rgba(0, 229, 255, 0.1);
            border: 1px dashed var(--accent);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 32px;
            transition: transform 0.3s ease;
        }

        .card:hover .icon-box {
            transform: rotate(15deg) scale(1.1);
            background: rgba(0, 229, 255, 0.2);
        }

        .card-content {
            flex: 1;
        }

        .card h2 {
            font-size: 1.4rem;
            margin: 0 0 8px 0;
            font-weight: 600;
        }

        .card p {
            font-size: 0.85rem;
            line-height: 1.5;
            color: var(--text-sub);
            margin: 0;
        }

        .footer {
            margin-top: auto;
            padding: 40px 20px;
            text-align: center;
            font-size: 0.8rem;
            letter-spacing: 0.1em;
            color: #ddd;
            text-shadow: 0 1px 3px rgba(0,0,0,0.8);
        }

        .company-name {
            color: var(--accent);
            font-weight: bold;
            text-decoration: none;
        }

        @media (max-width: 500px) {
            .grid { grid-template-columns: 1fr; }
            .card { flex-direction: column; text-align: center; }
            h1 { font-size: 2rem; }
        }




.ad-block {
    width: 90%;
    max-width: 900px;
    margin: 40px auto 20px;
    padding: 20px 25px;
    background: rgba(30, 41, 59, 0.6);
    border: 1px solid rgba(255,255,255,0.08);
    border-radius: 16px;
    backdrop-filter: blur(10px);
}

.ad-title {
    font-size: 1.1rem;
    color: var(--accent);
    margin-bottom: 15px;
    letter-spacing: 0.15em;
}

.ad-items {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.ad-item {
    flex: 1;
    min-width: 200px;
    background: rgba(255,255,255,0.03);
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 12px;
    padding: 15px;
    text-decoration: none;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 12px;
    transition: 0.3s;
}

.ad-item:hover {
    border-color: var(--accent);
    transform: translateY(-3px);
}

.ad-thumb {
    font-size: 1.6rem;
}

.ad-text {
    font-size: 0.9rem;
    color: var(--text-sub);
}


.guide-block {
    width: 90%;
    max-width: 900px;
    margin: 40px auto 20px;
    background: rgba(30, 41, 59, 0.6);
    border: 1px solid rgba(255,255,255,0.08);
    border-radius: 16px;
    backdrop-filter: blur(10px);
    overflow: hidden;
}

.guide-header {
    padding: 15px 20px;
    font-size: 1rem;
    letter-spacing: 0.15em;
    color: var(--accent);
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    user-select: none;
}

.guide-arrow {
    transition: transform 0.3s ease;
}

.guide-body {
    max-height: 0;
    overflow: hidden;
    padding: 0 20px;
    color: var(--text-sub);
    font-size: 0.9rem;
    line-height: 1.6;
    transition: max-height 0.4s ease, padding 0.4s ease;
}

.guide-body.open {
    max-height: 500px;
    padding: 20px;
}

.guide-body.open ~ .guide-header .guide-arrow {
    transform: rotate(180deg);
}