:root{--bg: #eef1f7;--ink: #161b33;--muted: #64748b;--panel: #ffffff;--blue: #2563eb;--red: #dc2626;--line: #dde3ee}*{box-sizing:border-box;margin:0;padding:0}body{font-family:Space Grotesk,sans-serif;background:var(--bg);color:var(--ink);min-height:100vh;-webkit-font-smoothing:antialiased}.page{max-width:780px;margin:0 auto;padding:2.2rem 1.25rem 3rem}.head{display:flex;align-items:flex-end;justify-content:space-between;gap:1rem;margin-bottom:1.6rem}.kicker{font-size:.78rem;font-weight:600;color:var(--muted);margin-bottom:.3rem}h1{font-size:clamp(1.6rem,4vw,2.2rem);font-weight:700;letter-spacing:-.02em}.step-pill{font-size:.78rem;font-weight:600;color:var(--muted);border:1px solid var(--line);background:var(--panel);border-radius:999px;padding:.35rem .8rem;white-space:nowrap}.diagram-card{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:.6rem .8rem}.seq{display:block;width:100%;height:auto}.life{stroke:#b9c4dc;stroke-width:2;stroke-dasharray:6 6}.lifedot{fill:var(--ink)}.actor{font-size:19px;font-weight:700;fill:var(--ink)}.actor-sub{font-size:11.5px;fill:var(--muted)}.arrow line{stroke:currentColor;stroke-width:2.2}.arrow .lbl{font-size:13.5px;font-weight:500;fill:currentColor}.arrow .lbl.resent{fill:var(--red)}.arrow .tag{font-family:JetBrains Mono,monospace;font-size:10px;font-weight:600;fill:var(--muted)}.arrow:not(.active):not(.ghost){opacity:.45}.arrow.active line{stroke-dasharray:380;stroke-dashoffset:380;animation:draw .55s ease-out forwards}@keyframes draw{to{stroke-dashoffset:0}}.arrow.active .lbl{animation:fadein .4s ease-out .35s both}@keyframes fadein{0%{opacity:0}to{opacity:1}}.arrow.ghost line{stroke:var(--red);stroke-width:2}.arrow.ghost .lbl{fill:var(--red);font-weight:600;animation:fadein .5s ease-out both}.timeaxis{stroke:#b9c4dc;stroke-width:1.6}.timelabel{font-size:12px;font-weight:600;fill:#8fa0c9}.caption{margin:1.1rem auto 0;max-width:560px;text-align:center;font-size:.92rem;line-height:1.55;color:#3a4266;animation:pop .3s ease-out both}.caption.final{font-size:1rem;color:var(--ink)}.caption strong{font-weight:700;color:var(--ink)}@keyframes pop{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}.controls{margin-top:1.4rem;display:flex;align-items:center;justify-content:center;gap:.6rem;flex-wrap:wrap}.btn{font-family:inherit;font-size:.82rem;font-weight:600;padding:.5rem 1rem;border-radius:8px;border:1px solid var(--line);background:var(--panel);color:var(--ink);cursor:pointer;transition:background .12s ease}.btn:hover:not(:disabled){background:#f1f4fa}.btn:disabled{opacity:.4;cursor:default}.btn:focus-visible,.dot-btn:focus-visible{outline:2px solid var(--blue);outline-offset:2px}.btn.primary{background:var(--ink);border-color:var(--ink);color:#fff}.btn.primary:hover:not(:disabled){background:#2a3158}.dots{display:flex;gap:.4rem}.dot-btn{width:10px;height:10px;border-radius:50%;border:none;background:#c9d2e4;cursor:pointer;padding:0;transition:background .12s ease,transform .12s ease}.dot-btn:hover{transform:scale(1.3)}.dot-btn.done{background:#8fa0c9}.dot-btn.active{background:var(--ink);transform:scale(1.3)}.credit{margin-top:2.2rem;font-size:.72rem;color:var(--muted);text-align:center}@media(prefers-reduced-motion:reduce){.caption,.arrow.active line,.arrow.active .lbl,.arrow.ghost .lbl{animation:none!important;stroke-dashoffset:0!important}}