@import url('https://fonts.googleapis.com/css2?family=DM+Mono:wght@400;500&family=Space+Grotesk:wght@400;500;600;700&display=swap');
:root{--ink:#17211f;--muted:#6a7772;--paper:#f5f4ef;--panel:#fbfaf6;--line:#d8ddd5;--lime:#c9ef55;--coral:#ff806b;--blue:#cde7ee;--shadow:0 16px 50px #17211f0d}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:'Space Grotesk',sans-serif}body:before{content:'';position:fixed;inset:0;pointer-events:none;opacity:.35;background-image:linear-gradient(#17211f08 1px,transparent 1px),linear-gradient(90deg,#17211f08 1px,transparent 1px);background-size:44px 44px;mask-image:linear-gradient(to bottom,#000,transparent 85%)}.topbar{height:78px;display:flex;align-items:center;justify-content:space-between;padding:0 clamp(24px,5vw,76px);border-bottom:1px solid var(--line);position:relative;z-index:1;background:#f5f4efcc;backdrop-filter:blur(12px)}.brand{display:flex;gap:11px;align-items:center;text-decoration:none;color:var(--ink);font-size:20px;line-height:1.05;letter-spacing:.02em}.brand b{font-size:15px}.brand-mark{display:grid;place-items:center;width:34px;height:34px;border-radius:50%;background:var(--ink);color:var(--lime);font-size:21px;font-family:Georgia,serif}.topbar-note,.mono{font-family:'DM Mono',monospace;font-size:11px;letter-spacing:.04em;color:var(--muted)}.status-dot{display:inline-block;width:7px;height:7px;border-radius:50%;background:#69b873;margin-right:8px}.hero{max-width:1280px;margin:0 auto;padding:60px;display:flex;justify-content:space-between;align-items:end;position:relative}.eyebrow{font-family:'DM Mono',monospace;text-transform:uppercase;font-size:10px;letter-spacing:.14em;color:var(--muted);margin:0 0 20px}.hero h1{font-size:80px;line-height:.93;letter-spacing:-.07em;margin:0;font-weight:600}.hero h1 em{font-family:Georgia,serif;font-weight:400;color:#ea654f}.hero-text{max-width:430px;color:var(--muted);font-size:16px;line-height:1.6;margin:30px 0 0}.hero-equation{width:190px;height:190px;border:1px solid var(--ink);border-radius:50%;display:flex;align-items:center;justify-content:center;gap:13px;transform:rotate(8deg);font-family:Georgia,serif;font-size:35px}.hero-equation span{color:#ea654f}.hero-equation i{font-style:normal;font-family:'DM Mono',monospace;font-size:18px}.hero-equation strong{font-weight:400;color:#4c9aa8}.workspace{max-width:1280px;margin:0 auto;display:grid;grid-template-columns:minmax(260px,315px) 1fr;gap:1px;background:var(--line);border:1px solid var(--line);box-shadow:var(--shadow);position:relative}.concept-panel,.solver-panel{background:var(--panel);padding:32px}.panel-heading{display:flex;align-items:start;justify-content:space-between;gap:16px}.panel-heading h2{font-size:22px;letter-spacing:-.04em;margin:0}.count{font:12px 'DM Mono',monospace;background:var(--lime);padding:7px 9px;border-radius:50%;min-width:30px;text-align:center}.search-wrap{display:flex;align-items:center;gap:9px;border-bottom:1px solid var(--line);padding:18px 0 10px;color:var(--muted)}.search-wrap span{font-size:22px}.search-wrap input{border:0;background:transparent;outline:0;width:100%;font:14px 'Space Grotesk',sans-serif;color:var(--ink)}.concept-list{display:grid;gap:6px;margin-top:18px}.concept-button{display:flex;align-items:center;gap:12px;width:100%;text-align:left;border:1px solid transparent;background:transparent;padding:11px 10px;color:var(--ink);cursor:pointer;font:500 14px 'Space Grotesk',sans-serif;transition:.2s}.concept-button:hover{background:#eef0e8}.concept-button.active{border-color:var(--ink);background:var(--ink);color:var(--paper)}.concept-icon{font:18px Georgia,serif;width:25px;color:#5b9ea9}.active .concept-icon{color:var(--lime)}.concept-category{font:9px 'DM Mono',monospace;color:var(--muted);margin-left:auto}.active .concept-category{color:#bac2b8}.solver-panel{padding:32px clamp(28px,5vw,72px) 52px;min-height:600px}.solver-heading{align-items:center}.tag{font:10px 'DM Mono',monospace;color:#4c9aa8;border:1px solid #a8d0d7;border-radius:99px;padding:7px 10px}.solver-description{color:var(--muted);font-size:14px;margin:14px 0 30px}.solver-form{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px 20px;max-width:680px}.field label{display:block;font:10px 'DM Mono',monospace;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin-bottom:8px}.field input,.field select{width:100%;border:1px solid var(--line);background:#fffefa;color:var(--ink);font:16px 'Space Grotesk',sans-serif;padding:13px 14px;outline:0;border-radius:2px}.field input:focus,.field select:focus{border-color:#4c9aa8;box-shadow:0 0 0 3px #cde7ee88}.field small{display:block;margin-top:5px;color:var(--muted);font-size:11px}.form-actions{display:flex;align-items:center;gap:17px;margin:30px 0 0}.solve-button{border:0;background:var(--coral);color:#fff;padding:14px 17px;display:flex;gap:28px;align-items:center;font:600 14px 'Space Grotesk',sans-serif;cursor:pointer;box-shadow:4px 4px 0 var(--ink);transition:.15s}.solve-button:hover{transform:translate(2px,2px);box-shadow:2px 2px 0 var(--ink)}.solve-button b{font-size:19px;font-weight:400}.reset-button{border:0;background:transparent;color:var(--muted);font:12px 'DM Mono',monospace;cursor:pointer;padding:10px}.solution{border-top:1px solid var(--line);margin-top:38px;padding-top:26px}.solution-empty{text-align:center;padding:26px;color:var(--muted)}.empty-symbol{display:block;color:#ea654f;font:34px Georgia,serif;margin-bottom:12px}.solution-empty h3{color:var(--ink);font-size:16px;margin:0 0 8px}.solution-empty p{font-size:13px;margin:0}.solution-header{display:flex;justify-content:space-between;align-items:start;margin-bottom:20px}.solution-header h3{font-size:19px;margin:0;letter-spacing:-.03em}.answer-badge{background:var(--lime);padding:12px 15px;font:600 16px 'DM Mono',monospace}.step{display:grid;grid-template-columns:36px 1fr;gap:13px;margin:15px 0;align-items:start}.step-number{font:11px 'DM Mono',monospace;background:var(--ink);color:var(--lime);width:28px;height:28px;display:grid;place-items:center}.step h4{margin:2px 0 6px;font-size:13px}.formula{font:16px Georgia,serif;color:#375e63;background:var(--blue);padding:10px 12px;display:inline-block;max-width:100%;overflow-wrap:anywhere}.step p{font-size:13px;color:var(--muted);line-height:1.5;margin:5px 0}.error-message{color:#a34232;background:#ffe1d9;border-left:3px solid var(--coral);font-size:13px;padding:12px;margin-top:18px}footer{max-width:1280px;margin:0 auto;padding:25px clamp(24px,5vw,76px);display:flex;justify-content:space-between;color:var(--muted);font-size:12px} @media(max-width:760px){.topbar{height:68px}.topbar-note{display:none}.hero{padding-top:60px;padding-bottom:58px}.hero-equation{width:85px;height:85px;font-size:23px;gap:6px}.hero h1{font-size:52px}.hero-text{font-size:14px;margin-top:22px}.workspace{display:block;margin:0 14px}.concept-panel,.solver-panel{padding:24px}.concept-list{grid-template-columns:repeat(2,minmax(0,1fr))}.concept-button{padding:10px 8px;font-size:12px}.concept-category{display:none}.solver-form{grid-template-columns:1fr}.solver-heading{align-items:start;flex-direction:column}.solution-header{display:block}.answer-badge{display:inline-block;margin-top:15px}.hero{padding-left:24px;padding-right:24px}footer{padding-left:24px;padding-right:24px}}