/* ── background ── */
.bg {
    position: fixed;
    inset: 0;
    background: url('../image/top_back.png') center center / cover no-repeat;
    z-index: 0;
}

.bg-overlay {
    position: fixed;
    inset: 0;
    background: var(--black);
    opacity: 0.52;
    z-index: 0;
}

/* ── layout ── */
.container {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 40px 24px;
    gap: var(--gap-md);
    animation: fadeUp 1.4s cubic-bezier(0.22, 0.61, 0.36, 1) both;
}

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(24px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ── logo ── */
.logo img {
    max-width: 420px;
    width: min(420px, 80vw);
    filter: drop-shadow(0 2px 24px var(--black));
}

/* ── gold divider ── */
.divider {
    width: 36px;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--gold), transparent);
}

/* ── button layout (style.css / login.css のベースをオーバーライド) ── */
.btn-login {
    display: inline-block;
    width: auto;
    padding: 14px 60px;
    font-size: var(--fs-small);
    letter-spacing: 0.45em;
    color: var(--white);
    margin-top: 0;
}
.btn-login:hover {
    color: var(--white);
    background: var(--gold);
    border-color: var(--gold);
}

/* ── responsive ── */
@media (max-width: 479px) {
    .container { gap: var(--gap-sm); }
    .btn-login { padding: 13px 40px; }
}

@media (min-width: 768px) {
    .logo img { max-width: 480px; }
}