:root{--brand:#118AB2;--brand-dark:#0e7396;--pale:#E0F7FA;--bg:#F8FAFC;--surface:#fff;--text:#1E293B;--muted:#64748B;--border:#E2E8F0;--radius:16px;--radius-sm:8px}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%}
body{font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Hiragino Sans","Noto Sans JP",sans-serif;color:var(--text);line-height:1.6;background:var(--bg) radial-gradient(900px 500px at 50% -10%,var(--pale),transparent 70%) no-repeat}
.stage{min-height:100vh;min-height:100dvh;display:flex;align-items:center;justify-content:center;padding:24px 16px}
.card{width:100%;max-width:440px;background:var(--surface);border-radius:var(--radius);box-shadow:0 4px 12px rgba(0,0,0,.1);padding:32px 24px;text-align:center;animation:fade .4s ease both}
.logo{width:72px;height:72px;display:block;margin:0 auto 16px}
.brandname{font-size:.75rem;font-weight:500;letter-spacing:.05em;color:var(--muted);margin:0 0 16px}
h1{font-size:1.5rem;font-weight:600;line-height:1.35;margin:0 0 8px}
p{margin:0 0 16px;color:var(--muted);font-size:1rem}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:48px;padding:12px 32px;background:var(--brand);color:#fff;border-radius:var(--radius-sm);font-size:1.0625rem;font-weight:600;text-decoration:none;margin-top:8px}
.btn:hover,.btn:focus-visible{background:var(--brand-dark)}
.btn:focus-visible{outline:3px solid var(--pale);outline-offset:2px}
.spinner{width:36px;height:36px;margin:8px auto 16px;border:4px solid var(--pale);border-top-color:var(--brand);border-radius:50%;animation:spin .9s linear infinite}
[hidden]{display:none!important}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes fade{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
@media (prefers-reduced-motion:reduce){.spinner{animation-duration:3s}.card{animation:none}}
@media (min-width:600px){.card{padding:40px 40px}}