:root{color-scheme:light;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;background:#eef1f4;color:#1c222b;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}*{box-sizing:border-box}body{min-width:320px;min-height:100vh;margin:0}button{font:inherit}.app-shell{width:min(1160px,100%);min-height:100vh;margin:0 auto;padding:32px;display:grid;grid-template-columns:minmax(0,760px) minmax(260px,1fr);gap:20px;align-items:start}.calculator,.history{border:1px solid #d5dce3;border-radius:8px;background:#fff;box-shadow:0 18px 45px #1f2d3d1f}.calculator{padding:20px}.calculator__topbar{display:flex;justify-content:space-between;gap:16px;align-items:start;margin-bottom:16px}.eyebrow{margin:0 0 4px;color:#687384;font-size:.76rem;font-weight:700;text-transform:uppercase}h1,h2{margin:0;color:#141922}h1{font-size:1.65rem}h2{font-size:1rem}.mode-toggle{min-width:132px;display:grid;grid-template-columns:1fr 1fr;border:1px solid #cbd4dd;border-radius:8px;overflow:hidden}.mode-toggle button{min-height:38px;border:0;background:#f7f9fb;color:#445063;font-weight:800;cursor:pointer}.mode-toggle button+button{border-left:1px solid #cbd4dd}.mode-toggle .is-active{background:#1d4ed8;color:#fff}.display{min-height:154px;padding:18px;border-radius:8px;background:#172033;color:#fff;display:flex;flex-direction:column;gap:12px}.display__status{display:flex;justify-content:space-between;color:#9fb0c8;font-size:.78rem;font-weight:800;text-transform:uppercase}.display__expression{min-height:42px;overflow-wrap:anywhere;color:#f8fafc;font-size:clamp(1.35rem,3vw,2.2rem);line-height:1.15}.display__result{min-height:32px;overflow-wrap:anywhere;color:#93e0a2;font-size:1.25rem;font-weight:800;text-align:right}.display__result--error{color:#ffb4a8}.muted{color:#73839c}.keypad-layout{display:grid;grid-template-columns:minmax(220px,.95fr) minmax(270px,1.05fr);gap:12px;margin-top:14px}.keypad{display:grid;gap:8px}.keypad--scientific{grid-template-columns:repeat(3,minmax(0,1fr))}.keypad--primary{grid-template-columns:repeat(4,minmax(0,1fr))}.key{min-width:0;min-height:54px;border:1px solid #d5dce3;border-radius:8px;background:#f7f9fb;color:#1f2937;font-size:1rem;font-weight:800;cursor:pointer;transition:background-color .12s ease,transform .12s ease,border-color .12s ease}.key:hover{background:#eef4ff;border-color:#9ab7eb}.key:active{transform:translateY(1px)}.key--number{background:#fff}.key--operator,.key--constant,.key--scientific{color:#174ea6}.key--control{color:#455366}.key--danger{background:#fff1f0;color:#b42318;border-color:#ffd1cc}.key--equals{background:#16845b;color:#fff;border-color:#16845b}.key--equals:hover{background:#126f4d;border-color:#126f4d}.key--wide{grid-column:span 2}.key--tall{grid-row:span 2;min-height:116px}.history{min-height:300px;padding:18px}.history__header{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:12px}.history__header button{min-height:34px;border:1px solid #d5dce3;border-radius:8px;background:#fff;color:#465469;font-weight:800;cursor:pointer}.history__header button:disabled{color:#a5afbd;cursor:not-allowed}.history__list{display:grid;gap:8px;margin:0;padding:0;list-style:none}.history__list button{width:100%;min-height:74px;padding:10px;border:1px solid #d9e1e9;border-radius:8px;background:#f8fafc;color:#1f2937;text-align:left;cursor:pointer}.history__expression,.history__result,.history__mode{display:block;overflow-wrap:anywhere}.history__expression{color:#536173;font-size:.82rem}.history__result{margin-top:3px;font-size:1rem;font-weight:800}.history__mode{margin-top:4px;color:#738095;font-size:.7rem;font-weight:800}.history__empty{margin:0;color:#6b7585}@media(max-width:900px){.app-shell{grid-template-columns:1fr;padding:18px}.keypad-layout{grid-template-columns:1fr}.keypad--scientific{grid-template-columns:repeat(6,minmax(0,1fr))}}@media(max-width:560px){.app-shell{padding:10px}.calculator,.history{padding:12px}.calculator__topbar{align-items:stretch;flex-direction:column}.mode-toggle{width:100%}.keypad--scientific{grid-template-columns:repeat(3,minmax(0,1fr))}.key{min-height:50px;font-size:.95rem}}