:root{--sumi:#1f2d36;--aiiro:#245260;--teal:#2d7f7b;--cyan:#6ec6d9;--gofun:#f7f5ef;--paper:#fffdf8;--text:#1f2d36;--muted:#667782;--line:rgba(31,45,54,.14);--shadow:0 18px 45px rgba(31,45,54,.14);--kurenai:#b84a4a;--r1:#e39a3b;--r2:#4b9fc5}*{box-sizing:border-box}html,body{margin:0;min-height:100%}body{font-family:Segoe UI,Yu Gothic UI,Yu Gothic,Meiryo,Noto Sans JP,Arial,sans-serif;background:radial-gradient(circle at top left,rgba(110,198,217,.2),transparent 34rem),linear-gradient(180deg,var(--gofun),#edf3ee);color:var(--text)}body.dark{--paper:#17242c;--text:#f7f5ef;--muted:#b7c6cb;--line:rgba(247,245,239,.16);--shadow:0 18px 45px rgba(0,0,0,.32);background:radial-gradient(circle at bottom right,rgba(45,127,123,.26),transparent 26rem),linear-gradient(180deg,#0f1a20,#1f2d36)}button,input{font:inherit}button{touch-action:manipulation}.app-shell{width:min(100%,760px);margin:0 auto;min-height:100vh;padding:18px 14px 28px}.topbar{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:14px}.brand-mark{display:inline-flex;align-items:center;gap:8px;font-weight:700;letter-spacing:.02em;color:var(--aiiro)}body.dark .brand-mark{color:var(--cyan)}.brand-dot{width:13px;height:13px;border-radius:999px;background:linear-gradient(135deg,var(--teal),var(--cyan));box-shadow:0 0 0 5px #2d7f7b1f}.icon-btn{width:44px;height:44px;display:inline-grid;place-items:center;border-radius:999px;border:1px solid var(--line);background:#24526014;color:var(--text);cursor:pointer;font-size:1.1rem}body.dark .icon-btn{background:#ffffff14}.card{background:color-mix(in srgb,var(--paper) 92%,transparent);border:1px solid var(--line);border-radius:24px;box-shadow:var(--shadow);padding:20px;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.hero-title{font-size:clamp(1.55rem,5vw,2.2rem);line-height:1.18;margin:12px 0 10px}.subtitle,.muted{color:var(--muted);line-height:1.75}.stealth-progress{display:flex;align-items:center;gap:8px;margin:14px 0 18px;min-height:18px}.progress-dot{width:13px;height:13px;border-radius:999px;background:transparent;border:2px solid currentColor;opacity:.9}.progress-dot.done{background:currentColor}.progress-dot.r1{color:var(--r1)}.progress-dot.r2{color:var(--r2)}.progress-gap{width:8px}.question-nav{display:grid;grid-template-columns:42px repeat(4,1fr) 42px;gap:6px;margin:10px 0 16px;align-items:center}.nav-btn{min-height:38px;border-radius:14px;border:1px solid var(--line);background:#24526012;color:var(--text);cursor:pointer;font-weight:700}.nav-btn.current{background:linear-gradient(135deg,var(--teal),var(--cyan));color:#fff;border-color:transparent}.nav-btn.solved:not(.current){background:#2d7f7b21;color:var(--teal)}.nav-btn:disabled,.nav-btn.locked{cursor:not-allowed;opacity:.34;filter:grayscale(.2);background:#6677821a;color:var(--muted)}body.dark .nav-btn.solved:not(.current){color:var(--cyan);background:#6ec6d91f}.question-image-wrap{position:relative;margin:14px 0}.question-image{width:100%;border-radius:18px;border:1px solid var(--line);background:#c8dccb29;display:block;-webkit-user-select:none;user-select:none;-webkit-user-drag:none}.paper-drop-target{touch-action:none;-webkit-user-select:none;user-select:none;-webkit-user-drag:none;cursor:grab}.paper-drop-target:active{cursor:grabbing;transform:translateY(2px)}.ice-hotspot{position:absolute;display:block;border:0;background:#fff0;border-radius:999px;cursor:pointer;touch-action:none}.ice-hotspot:focus-visible{outline:2px dashed rgba(110,198,217,.85);outline-offset:3px}.answer-row{display:grid;gap:10px;margin-top:16px}input[type=text],input[type=password]{width:100%;padding:14px;border-radius:16px;border:1px solid var(--line);background:#ffffffc7;color:#15222a;outline:none}body.dark input[type=text],body.dark input[type=password]{background:#ffffff14;color:var(--text)}.btn-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}.btn{border:0;border-radius:16px;padding:12px 15px;background:var(--aiiro);color:#fff;font-weight:700;cursor:pointer;box-shadow:0 10px 20px #2452602e}.btn.secondary{background:#24526014;color:var(--text);border:1px solid var(--line);box-shadow:none}.btn.warn{background:var(--kurenai)}.pill{display:inline-flex;align-items:center;gap:6px;padding:7px 10px;border-radius:999px;background:#2d7f7b1f;color:var(--teal);font-size:.82rem;font-weight:700}body.dark .pill{color:var(--cyan);background:#6ec6d91f}.notice{margin-top:12px;border-left:4px solid var(--teal);padding:10px 12px;background:#2d7f7b1a;border-radius:14px;line-height:1.6}.error{border-left-color:var(--kurenai);background:#b84a4a1f}.hidden-instruction{margin:6px 0 0;padding:0 4px;min-height:1.1em;font-size:.78rem;line-height:1.5;color:#1f2d3609;background:transparent;border:0;-webkit-user-select:none;user-select:none;letter-spacing:.02em}body.dark .hidden-instruction{margin-top:10px;padding:8px 10px;border-radius:12px;color:#6ec6d9f0;background:#6ec6d914;border:1px solid rgba(110,198,217,.18)}.result-card{text-align:center}.result-symbol{width:72px;height:72px;display:inline-grid;place-items:center;border-radius:999px;margin:8px auto 12px;color:#fff;background:linear-gradient(135deg,var(--teal),var(--cyan));box-shadow:0 16px 30px #2d7f7b33;font-size:2rem;font-weight:800}.result-symbol.moon{background:linear-gradient(135deg,#1f2d36,#245260);color:var(--cyan)}.result-title{font-size:1.6rem;margin:8px 0 6px}.final-message{font-size:1.55rem;line-height:1.6;color:var(--teal);font-weight:800}body.dark .final-message{color:var(--cyan)}.final-free-message{margin-top:14px;padding:14px;border-radius:18px;border:1px solid var(--line);background:#c8dccb24;line-height:1.8;white-space:pre-wrap}.admin-list{padding:0;margin:12px 0 0;list-style:none;display:grid;gap:8px}.admin-list li{padding:10px 12px;border:1px solid var(--line);border-radius:14px;background:#ffffff59}.footer-note{margin-top:14px;font-size:.82rem;color:var(--muted);text-align:center}@media (orientation:landscape) and (max-height:520px){.app-shell{width:min(100%,980px);padding:10px}.card{padding:12px}.hero-title{font-size:1.35rem;margin:6px 0}.question-image{max-height:62vh;object-fit:contain}}