Passkeys

<div class="sd"><div class="sd-head"><strong>PASSKEY</strong><span id="state">live check</span></div><div class="sd-stage"><div class="tile" id="server">challenge</div><div class="arrow" id="arrow">→</div><div class="device"><div class="lock">PRIVATE KEY</div><div id="device-state">unlock</div></div><div class="tile good" id="verify">verify</div></div><div class="sd-foot"><span id="caption">checking boundary</span><span>tap to step</span></div></div>

.sd{box-sizing:border-box;width:min(94vw,700px);height:min(86vh,318px);padding:clamp(9px,2.3vmin,18px);border:1px solid var(--line);border-radius:14px;background:var(--surface);color:var(--fg);display:flex;flex-direction:column;gap:clamp(6px,1.8vmin,12px);font:600 clamp(12px,2.6vmin,16px)/1.25 var(--font-sans, sans-serif)}.sd *{box-sizing:border-box}.sd-head,.sd-foot{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:1.25em}.sd-head strong{color:var(--accent);letter-spacing:.06em}.sd-head span,.sd-foot{color:var(--muted)}.sd-foot{font-size:clamp(12px,2.4vmin,14px)}.sd-stage{position:relative;flex:1;min-height:0;display:flex;align-items:center;justify-content:center;gap:clamp(6px,2vmin,18px);overflow:hidden}.sd .mono{font-family:ui-monospace,monospace}.sd .tile{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:clamp(5px,1.5vmin,10px);text-align:center}.sd .good{color:var(--accent);border-color:var(--accent)}.sd .bad{color:var(--accent-3);border-color:var(--accent-3)}.sd .arrow{color:var(--muted);font-size:clamp(15px,4vmin,28px)}.sd .active{background:color-mix(in srgb,var(--accent) 16%,var(--surface));border-color:var(--accent)}.sd .blocked{background:color-mix(in srgb,var(--accent-3) 13%,var(--surface));border-color:var(--accent-3)}.device{border:2px solid var(--accent);border-radius:12px;padding:clamp(6px,2vmin,13px);text-align:center;min-width:30%;background:color-mix(in srgb,var(--accent) 10%,var(--surface))}.lock{font:700 clamp(12px,2.4vmin,13px) ui-monospace,monospace;color:var(--accent)}.device #device-state{margin-top:5px}.sd-stage>.tile{max-width:24%;overflow-wrap:anywhere}

let n=-1;function advance(){n=(n+1)%3;document.getElementById('server').textContent=['challenge','challenge','public key'][n];document.getElementById('device-state').textContent=['unlock','sign','signed'][n];document.getElementById('verify').textContent=['waiting','signature','verified'][n];document.getElementById('verify').classList.toggle('active',n===2);document.getElementById('state').textContent=['request','local signing','server check'][n];document.getElementById('caption').textContent=['server sends random challenge','device signs without sharing key','server checks with public key'][n]}advance();setInterval(advance,750);
document.querySelector('.sd').addEventListener('pointerdown',advance);