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button{background:#edf5f6;color:#315c67;border-radius:8px;padding:14px;text-align:left;min-height:48px;font-size:14px}.menu-grid small{display:block;font-size:11px;color:#69848e;line-height:1.6}.history-entry{display:block;width:100%;text-align:left;background:#f0f6f7;margin:8px 0;padding:12px;border-radius:5px;color:var(--ink);overflow-wrap:anywhere;font-size:14px}.history-entry small{display:block;color:var(--teal);margin-top:4px}#toast{position:fixed;bottom:22px;left:50%;transform:translateX(-50%);padding:12px 20px;border-radius:8px;background:#173e49;color:#fff;font-size:14px;max-width:90vw;box-shadow:0 4px 25px #1233;z-index:50;display:none}#toast.visible{display:block}.mobile-tabs{display:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}.skip{position:fixed;top:-100px;left:10px;padding:10px;background:white;z-index:100}.skip:focus{top:10px}.noscript{position:fixed;inset:0;background:white;display:grid;place-items:center;padding:30px;z-index:100}
@media(min-width:1500px){.layout{gap:40px;grid-template-columns:235px 410px minmax(360px,1fr)}}
@media(max-width:1190px){.layout{grid-template-columns:185px minmax(310px,360px) minmax(320px,1fr);gap:20px;padding:24px}.lesson{padding:22px}.calculator{padding:18px}.keypad{gap:8px}.header{padding:18px 24px}.lesson h2{font-size:25px}.curriculum h1{font-size:23px}}
@media(max-width:1030px) and (min-width:761px){.layout{grid-template-columns:minmax(300px,360px) minmax(320px,1fr)}.curriculum{grid-column:1/-1}.curriculum h1,.curriculum .intro,.curriculum>.section-label,.curriculum>.tiny{display:none}.progress-label{max-width:260px}progress{max-width:260px}#lesson-nav{display:flex;overflow-x:auto;gap:6px;margin:10px 0 0;padding-bottom:6px}.nav-group{display:none}.lesson-link{flex-shrink:0}.header-title{font-size:16px}}
@media(max-width:760px){.header{padding:14px 16px;min-height:70px;gap:8px}.brand{font-size:17px;gap:7px}.brand small{font-size:10px;letter-spacing:1px}.mark{font-size:25px}.header-title{display:none}.header>.quiet{font-size:12px;padding:8px 10px}.mobile-tabs{display:flex;position:sticky;top:0;z-index:10;background:#fff;border-bottom:1px solid var(--line);padding:0 16px;gap:22px}.mobile-tabs button{background:none;padding:14px 2px;color:#718893;border-bottom:3px solid transparent;font-size:14px}.mobile-tabs button[aria-pressed=true]{color:var(--teal);border-bottom-color:var(--teal);font-weight:700}.mobile-tabs span{font-size:11px;margin-left:8px}.layout{display:flex;flex-direction:column;padding:18px 16px 30px;gap:20px}.curriculum,.lab,.lesson{width:100%}.layout[data-view=lab] .curriculum,.layout[data-view=lab] .lesson{display:none}.layout[data-view=learn] .lab{display:none}.curriculum h1,.curriculum .intro,.curriculum>.section-label,.curriculum>.tiny{display:none}.progress-label{font-size:12px}#lesson-nav{display:flex;overflow-x:auto;gap:6px;margin:14px 0 0;padding-bottom:7px}.nav-group{display:none}.lesson-link{flex-shrink:0;font-size:13px;background:#edf2f4;padding:10px 12px}.lesson-link .num{display:none}.lab-heading{max-width:410px;margin:0 auto 12px}.calculator{padding:21px;max-width:390px}.key{min-height:46px}.controls button{min-height:38px}.device-caption{font-size:11px}.workspace{max-width:560px;margin:auto;padding:17px}.lesson{padding:22px 19px}.lesson h2{font-size:25px}.lesson-top{margin-bottom:16px}.lesson-actions{flex-wrap:wrap}.muted{font-size:14px}.step p{font-size:14px}.answer-row input{font-size:16px}.answer-row button{min-height:44px}.question{padding:14px}footer{padding:22px 18px;font-size:11px}.menu-grid button{font-size:13px}dialog{padding:20px}.step-controls button{min-height:44px}}
@media(max-width:360px){.layout{padding:14px 10px}.calculator{padding:16px}.keypad{gap:7px}.key{min-height:44px}.lesson{padding:18px 14px}.controls{gap:5px}.header{padding:12px}.header>.quiet{font-size:11px}.brand{font-size:15px}.practice-heading .tiny{font-size:11px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
.calculator{background:linear-gradient(120deg,#313437,#202426);border-color:#151a1d;border-radius:23px 23px 30px 30px;padding:20px 20px 22px}.device-top{align-items:flex-start}.device-top strong{font-style:italic;font-size:22px}.device-top span{font-size:12px}.solar{height:43px;width:115px;background:#322421;border:2px solid #151a1b;border-radius:10px}.device-sub{flex-direction:row-reverse;font-size:10px}.screen{background:#d8e8e0;border-color:#171f21;min-height:140px;padding:8px 10px}.screen.off>*{visibility:hidden}.navigation-pad{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));grid-template-rows:40px 40px 40px;gap:8px;margin:24px 0 17px;align-items:center}.navigation-pad button{position:relative;background:linear-gradient(#393f42,#242a2c);border:1px solid #0c1113;box-shadow:0 2px 2px #0008;border-radius:50%;color:#d3d8da;font:20px Arial,sans-serif;min-height:36px;width:38px;max-width:100%;justify-self:center}.navigation-pad button small{position:absolute;bottom:calc(100% + 3px);left:50%;transform:translateX(-50%);font:10px/1 sans-serif;white-space:nowrap;color:#bec8cc}.nav-on{grid-area:1/1}.nav-home{grid-area:1/2}.nav-up{grid-area:1/4}.nav-pageup{grid-area:1/6}.nav-settings{grid-area:2/1}.nav-back{grid-area:2/2}.nav-left{grid-area:2/3}.nav-ok{grid-area:2/4}.nav-right{grid-area:2/5}.nav-pagedown{grid-area:2/6}.nav-shift{grid-area:3/1}.nav-variables{grid-area:3/2}.nav-functions{grid-area:3/3}.nav-down{grid-area:3/4}.nav-catalog{grid-area:3/5}.nav-tools{grid-area:3/6}.navigation-pad .nav-shift{background:#355b76;color:#99d5ff}.navigation-pad .nav-shift small{color:#8dcff5}.navigation-pad .nav-variables,.navigation-pad .nav-functions{font-size:16px}.navigation-pad .nav-ok{font-size:15px;font-weight:bold}.navigation-pad .nav-pageup,.navigation-pad .nav-pagedown{border-radius:12px;box-shadow:none}.navigation-pad .pressed{outline:2px solid #8bccf8}.science-keypad{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:17px 7px;margin:20px 0 19px}.science-keypad .key{min-height:41px;width:41px;max-width:100%;justify-self:center;background:linear-gradient(#4a5052,#32383a);border:1px solid #15191a;border-radius:50%;font-size:16px;color:#eee;box-shadow:0 2px 2px #000a}.science-keypad .key:first-child{font-family:Georgia,serif;font-style:italic;font-size:23px}.keypad{gap:17px 9px;margin-top:19px}.keypad .key{border-radius:50%;aspect-ratio:1;min-height:42px;max-height:56px;justify-self:center;width:100%;max-width:56px;background:linear-gradient(#4b5153,#343a3c);border:1px solid #181d1e;color:#eef2f3;box-shadow:0 3px 2px #0008;font-size:24px}.keypad .key.accent{background:linear-gradient(#747f85,#566268)}.keypad .key.execute{background:linear-gradient(#4b5153,#343a3c);color:#fff;font-size:18px}.keypad .key[data-key=e]{font-size:16px}.keypad .key[data-key=format]{font-size:16px}.key small,.science-keypad .key small{color:#8ed1fc;position:absolute;top:-13px;left:0;right:auto;font-size:10px;line-height:1;opacity:1;white-space:nowrap}.keypad .key small{font-size:11px;top:-13px}.reference-photo{display:block;width:100%;max-width:420px;margin:0 auto}.screen #expression{font-size:16px;height:32px;padding-top:5px}.screen #display{font-size:24px;line-height:1.3;min-height:31px}#natural-expression{min-height:22px;overflow-x:auto;overflow-y:hidden;padding:3px 0;max-width:100%;font-size:16px}#exact-result{font-size:20px;text-align:right;overflow-x:auto;overflow-y:hidden;max-width:100%}#exact-result:empty{display:none}.katex{white-space:nowrap}#natural-expression .katex{font-size:1.1em}#exact-result .katex{font-size:1.1em}.device-caption .text-button{font-size:11px;padding:0}.menu-grid{max-height:58vh;overflow:auto;padding:2px}.reference-photo+ p{font-size:12px}.navigation-pad button:active{transform:translateY(1px);box-shadow:none}
@media(max-width:760px){.calculator{padding:19px;max-width:390px}.navigation-pad{grid-template-rows:42px 42px 42px;gap:9px}.navigation-pad button{min-height:40px;width:41px}.science-keypad{gap:18px 6px}.science-keypad .key{min-height:42px;width:42px}.keypad{gap:18px 9px}.keypad .key{min-height:45px;max-height:55px}.keypad .key small{font-size:11px}.screen #expression{font-size:16px}.navigation-pad button small{font-size:10px}.lesson-link{min-height:44px}.menu-grid button{min-height:48px}}
@media(max-width:360px){.calculator{padding:16px 13px}.navigation-pad{gap:8px 5px}.navigation-pad button{width:38px;min-height:38px}.science-keypad{gap:18px 5px}.science-keypad .key{width:39px;min-height:39px;font-size:15px}.keypad .key{min-height:44px}.key small,.science-keypad .key small{font-size:9px}}