*,*:before,*:after{box-sizing:border-box}body{margin:0;min-height:100vh;font-family:system-ui,-apple-system,sans-serif;font-size:18px;background:#fafafa;color:#1a1a1a;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:1rem}.calc-wrap{display:flex;flex-direction:column;align-items:center;gap:1rem}.calc-back{align-self:flex-start;font-size:.9rem}.calc-back a{color:#0d5c47;text-decoration:none}.calc-back a:hover{text-decoration:underline}.calculator{display:grid;grid-template-columns:repeat(4,1fr);gap:.5rem;max-width:280px;padding:1rem;background:#fff;border-radius:8px;box-shadow:0 2px 8px #00000014;border:1px solid #e0e0e0}.display{grid-column:1 / -1;padding:.75rem 1rem;background:#f5f5f5;border-radius:6px;text-align:right;font-variant-numeric:tabular-nums;min-height:2.5rem;font-size:1.5rem;word-break:break-all}.calculator button{padding:.75rem 1rem;font-size:1.1rem;border:1px solid #e0e0e0;border-radius:6px;background:#fff;cursor:pointer;transition:background .15s,border-color .15s}.calculator button:hover{background:#f0f0f0;border-color:#ccc}.calculator button:active{background:#e8e8e8}.calculator button.operator{background:#e8f2ef;border-color:#0d5c47;color:#0d5c47}.calculator button.operator:hover{background:#d4e9e2}.calculator button.span-two{grid-column:span 2}