:root{--paper:#fbfbf8;--ink:#18201d;--muted:#5d6460;--line:#dfe2dc;--blue:#183ee5;--blue-light:#edf1ff;--yellow:#eaff80;--sans:'DM Sans',Arial,sans-serif;--display:'Space Grotesk',Arial,sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.6 var(--sans)}button,input,select,textarea{font:inherit}button,a,input,select,textarea{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}a{color:inherit;text-underline-offset:4px}button{cursor:pointer}button:disabled{cursor:default}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid 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var(--line);color:var(--muted)}.top-nav{display:flex;align-items:center;gap:32px;margin-left:auto;font-size:14px;font-weight:600}.top-nav a{text-decoration:none;padding:9px 0}.top-nav a[aria-current=page]{box-shadow:0 2px var(--blue)}.site-layout{display:grid;grid-template-columns:260px minmax(0,1fr);max-width:1600px;margin:auto}.sidebar{padding:38px 22px 35px 30px;border-right:1px solid var(--line)}.sidebar-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:25px}.eyebrow{font-size:12px;font-weight:700;letter-spacing:.12em;line-height:1.5}.free-tag{font-size:11px;letter-spacing:.08em;background:var(--yellow);padding:2px 7px;font-weight:700}.lesson-link{display:flex;align-items:center;text-decoration:none;gap:13px;padding:14px 12px;margin:4px -8px;border-radius:3px;line-height:1.4;font-size:14px;transition:background .15s}.lesson-link:hover{background:#eff0eb}.lesson-link[aria-current=page]{background:var(--blue);color:#fff}.lesson-number{font:500 13px var(--display);opacity:.65;width:22px;flex-shrink:0}.lesson-link small{display:block;color:var(--muted);font-size:12px;margin-top:3px}.lesson-link[aria-current=page] small{color:#d9e1ff}.lesson-check{margin-left:auto;font-weight:700}.course-progress{border-top:1px solid var(--line);margin-top:30px;padding-top:25px}.course-progress>div{display:flex;justify-content:space-between;font-size:13px}.course-progress strong{font-family:var(--display);font-weight:500}progress{width:100%;height:4px;border:0;display:block;margin:15px 0;background:var(--line);accent-color:var(--blue)}progress::-webkit-progress-bar{background:var(--line)}progress::-webkit-progress-value{background:var(--blue)}.course-progress p{font-size:12px;color:var(--muted);line-height:1.5}.sidebar-note{display:flex;gap:10px;font-size:12px;color:var(--muted);margin-top:35px}.sidebar-note>span{font-size:26px;color:var(--blue)}main{padding:39px clamp(25px,4.2vw,72px) 70px;min-width:0}.lesson-meta{display:flex;align-items:center;gap:12px;color:var(--blue);margin-bottom:24px}.lesson-meta .duration{font-size:12px;letter-spacing:0;color:var(--muted);border-left:1px solid var(--line);padding-left:12px;font-weight:400}.intro{max-width:760px;color:var(--muted);font-size:18px;line-height:1.6;margin-bottom:28px}.intro strong{color:var(--ink);font-weight:500}.lesson-jumps{display:flex;gap:25px;border-bottom:1px solid var(--line);margin-bottom:28px;padding-bottom:13px;font-size:14px;font-weight:600}.lesson-jumps a{text-decoration:none}.lesson-jumps a:first-child{color:var(--blue)}.lab{border:1px solid var(--line);background:white;scroll-margin-top:25px}.lab-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:16px 24px;border-bottom:1px solid var(--line)}.lab-heading h2{font:600 15px 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14px;font-size:23px}.reading p{color:#434b46;line-height:1.85}.reading strong{color:var(--ink);font-weight:650}.reading ol,.reading ul{padding-left:23px;color:#434b46}.reading li{margin-bottom:12px;padding-left:6px}.source-note{border-top:1px solid var(--line);margin-top:30px;padding-top:18px;font-size:13px;color:var(--muted)}.source-note p{line-height:1.7;font-size:13px;margin-bottom:10px}.source-note a{color:var(--blue)}.quiz{margin:40px 0;padding:25px 28px;background:#f0f2ed;border:1px solid var(--line)}.quiz h3{font-size:22px;margin:13px 0 20px;line-height:1.35}.quiz-options{display:grid;gap:9px}.quiz-option{padding:13px 17px;border:1px solid #cdd2cd;background:var(--paper);text-align:left;font-size:14px;border-radius:3px}.quiz-option:hover{border-color:var(--blue)}.quiz-option[aria-pressed=true]{background:var(--blue-light);border-color:var(--blue);color:var(--blue)}.quiz-feedback{font-size:14px;margin:16px 0 0}.quiz-feedback:empty{display:none}.book-callout{display:grid;grid-template-columns:100px 1fr;gap:25px;align-items:center;margin:40px 0;background:#eaf0e9;padding:28px}.book-callout img{display:block;width:100%;height:auto;box-shadow:3px 5px 12px #0002}.book-callout h3{font-size:25px;margin:9px 0}.book-callout p{font-size:14px;margin-bottom:12px;color:#444e46}.book-callout a{font-size:14px;font-weight:600}.lesson-end{display:flex;align-items:center;justify-content:space-between;gap:20px;border-top:1px solid var(--line);padding-top:25px}.button{display:inline-flex;align-items:center;justify-content:center;gap:15px;background:var(--ink);color:#fff;padding:13px 20px;text-decoration:none;font-size:14px;font-weight:550;border:1px solid var(--ink);border-radius:3px;line-height:1.5}.button:hover{background:#343e37}.button.secondary{color:var(--ink);background:transparent;border-color:#bcc4bc}.button.secondary:hover{background:#eff0eb}.button.blue{background:var(--blue);border-color:var(--blue)}.button.blue:hover{background:#102fb5}.next-link{font-size:14px;font-weight:600;color:var(--blue);text-align:right}.checklist{display:grid;gap:13px}.check-item{display:flex;align-items:flex-start;gap:11px;font-size:14px;line-height:1.55;cursor:pointer}.check-item input{width:18px;height:18px;accent-color:var(--blue);margin:3px 0 0;flex-shrink:0}.check-item span{flex:1}.check-item small{display:block;font-size:12px;color:var(--muted);margin-top:4px}.lab .subhead{font-size:14px;margin:0 0 17px;font-weight:600}.scenario{font-size:15px;line-height:1.8;margin:0 0 24px}.scenario strong{font-weight:600}.choice-buttons{display:grid;gap:10px}.choice-buttons button{padding:12px;text-align:left;background:var(--paper);border:1px solid 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