* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    display: grid;
    place-items: center;
    padding: 24px;

    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "Helvetica Neue",
        "Yu Gothic",
        "Hiragino Kaku Gothic ProN",
        sans-serif;

    color: #1e1b4b;

    background:
        radial-gradient(circle at top left,
            #ede9fe 0,
            transparent 35%),
        radial-gradient(circle at bottom right,
            #fae8ff 0,
            transparent 38%),
        #fafafa;
}

.card {
    width: min(680px, 100%);
    padding: 56px 36px;
    text-align: center;

    background: rgba(255, 255, 255, 0.9);

    border: 1px solid rgba(255, 255, 255, 0.95);
    border-radius: 24px;

    box-shadow: 0 24px 70px rgba(76, 29, 149, 0.14);

    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.secret-icon {
    width: 86px;
    height: 86px;
    margin: 0 auto 24px;

    display: grid;
    place-items: center;

    border-radius: 50%;

    font-size: 42px;

    background: #f3e8ff;
}

h1 {
    margin: 0 0 14px;

    font-size: clamp(34px, 8vw, 54px);

    letter-spacing: 0.08em;
}

.description {
    margin: 0;

    font-size: 17px;
    line-height: 1.8;

    color: #6b7280;
}

.secret-content {
    margin-top: 32px;
    padding: 26px;

    background: #faf5ff;

    border: 1px solid #e9d5ff;
    border-radius: 18px;
}

.secret-content h2 {
    margin: 0 0 12px;

    font-size: 24px;
}

.secret-content p {
    margin: 0;

    font-size: 16px;
    line-height: 1.8;

    color: #6b7280;
}

.back-button {
    display: inline-block;

    margin-top: 30px;
    padding: 13px 24px;

    color: #ffffff;
    font-size: 15px;
    font-weight: bold;
    text-decoration: none;

    background: #7c3aed;

    border-radius: 12px;

    transition:
        transform 0.2s ease,
        background-color 0.2s ease,
        box-shadow 0.2s ease;
}

.back-button:hover {
    background: #6d28d9;

    transform: translateY(-2px);

    box-shadow: 0 10px 22px rgba(124, 58, 237, 0.28);
}

.back-button:active {
    transform: translateY(0);
}

.back-button:focus-visible {
    outline: 3px solid #c4b5fd;
    outline-offset: 4px;
}

.domain {
    margin-top: 30px;

    font-size: 14px;
    letter-spacing: 0.08em;

    color: #a78bfa;
}

@media (max-width: 500px) {
    .card {
        padding: 44px 24px;
    }

    .secret-icon {
        width: 78px;
        height: 78px;

        font-size: 38px;
    }

    .description {
        font-size: 15px;
    }

    .secret-content {
        padding: 20px 16px;
    }
}