:root{--bg: #0e1620;--panel: #15212e;--panel-2: #1d2c3c;--ink: #e7eef5;--muted: #8da3b6;--accent: #4a8cc0;--accent-2: #6fb3e0;--ok: #4caf7d;--warn: #d68a3a;--line: #293a4d}*{box-sizing:border-box}body{margin:0;background:radial-gradient(1200px 700px at 50% -10%,#1a2735,var(--bg));color:var(--ink);font-family:Segoe UI,system-ui,-apple-system,sans-serif}.balance-app{max-width:720px;margin:0 auto;padding:20px 16px 64px}header h1{margin:0;font-size:2.1rem;letter-spacing:.22em;font-weight:800;background:linear-gradient(90deg,var(--accent-2),var(--accent));-webkit-background-clip:text;background-clip:text;color:transparent}.tagline{margin:4px 0 16px;color:var(--muted);font-size:.92rem}.controls{display:flex;align-items:center;gap:10px;margin-bottom:16px;flex-wrap:wrap}.timer{margin-left:auto;font-variant-numeric:tabular-nums;color:var(--muted);font-size:1.1rem}.btn{background:var(--panel-2);color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:8px 14px;font-size:.95rem;cursor:pointer;transition:background .15s,transform .05s}.btn:hover{background:#25394d}.btn:active{transform:translateY(1px)}.btn.primary{background:linear-gradient(90deg,var(--accent),#3b78a8);border-color:transparent;font-weight:600}.board{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:18px}.equation{display:flex;flex-wrap:wrap;align-items:flex-end;gap:8px;justify-content:center;padding:8px 0 16px;border-bottom:1px dashed var(--line)}.species{display:flex;flex-direction:column;align-items:center;gap:6px}.formula{font-size:1.25rem;font-weight:600}.op{font-size:1.3rem;color:var(--muted);padding:0 2px 4px;align-self:flex-end}.op.arrow{color:var(--accent-2);font-size:1.5rem}.stepper{display:inline-flex;align-items:center;background:var(--panel-2);border:1px solid var(--line);border-radius:8px;overflow:hidden}.step{background:transparent;border:none;color:var(--accent-2);font-size:1.2rem;width:30px;height:30px;cursor:pointer}.step:hover{background:#2a4055}.coeff{min-width:28px;text-align:center;font-weight:700;font-variant-numeric:tabular-nums}.scales{display:grid;gap:8px;margin:16px 0}.scale{display:grid;grid-template-columns:1fr 48px auto 1fr;align-items:center;gap:10px;background:var(--panel-2);border:1px solid var(--line);border-radius:10px;padding:8px 12px}.scale.level{border-color:var(--ok)}.scale.tipped{border-color:var(--warn)}.pan{font-variant-numeric:tabular-nums;font-weight:700;font-size:1.05rem}.pan.left{text-align:right}.pan.right{text-align:left}.scale-label{text-align:center;font-weight:700;color:var(--accent-2)}.beam{text-align:center;font-size:1.1rem}.scale.level .beam{color:var(--ok)}.scale.tipped .beam{color:var(--warn)}.actions{display:flex;gap:10px;justify-content:center;margin-top:8px;flex-wrap:wrap}.predict-intro{color:var(--muted);text-align:center}.question{margin:14px 0}.question>p{margin:0 0 8px;font-weight:600}.options{display:flex;gap:8px;flex-wrap:wrap}.option{background:var(--panel-2);border:1px solid var(--line);color:var(--ink);border-radius:8px;padding:8px 14px;font-size:1.05rem;cursor:pointer}.option:hover{background:#25394d}.option.selected{border-color:var(--accent-2);background:#2a4a63}.yield-input{background:var(--panel-2);border:1px solid var(--line);color:var(--ink);border-radius:8px;padding:8px 12px;font-size:1.05rem;width:140px}.status{margin-top:14px;min-height:1.4em;text-align:center;color:var(--muted);font-size:.98rem}.status.ok{color:var(--ok)}.status.warn{color:var(--warn)}