.lesson-format-tabs{display:flex;gap:0;border-bottom:1px solid var(--line);margin:24px 0 28px;overflow-x:auto}
.lesson-format-tabs button{font:600 14px Manrope,sans-serif;background:none;border:0;border-bottom:3px solid transparent;padding:15px 18px;color:var(--muted);cursor:pointer;white-space:nowrap}
.lesson-format-tabs button[aria-selected=true]{border-color:var(--teal);color:var(--teal)}
.lesson-format-tabs button:focus-visible,.issue-tree-branch button:focus-visible,.example-stage-nav button:focus-visible{outline:3px solid var(--teal);outline-offset:3px}
.lesson-panel[hidden]{display:none}
.lesson-objectives{padding:20px 24px;background:#edf4f6;border-left:3px solid #6f9ba6;margin:0 0 30px;border-radius:0 5px 5px 0}
.lesson-objectives h2{font-size:16px;margin:0 0 10px}.lesson-objectives ul{padding-left:20px;margin:0;color:#415970;line-height:1.75;font-size:16px}
.lesson-reading section>p+p{margin-top:14px}.lesson-reading section>p{max-width:67ch}
.lesson-reading h2{font-size:24px;letter-spacing:-.6px;margin-bottom:16px}
.lesson-reading p{line-height:1.85;font-size:18px}
.lesson-panel-footer{border-top:1px solid var(--line);margin-top:30px;padding:24px 0;display:flex;justify-content:flex-end}
.lesson-tree{margin:32px 0 40px;padding:26px;background:#fff;border:1px solid var(--line);border-radius:7px}
.tree-introduction h2,.lesson-calculator h2{font-size:22px;margin:0 0 10px;letter-spacing:-.5px}
.tree-introduction>p,.lesson-calculator>p{font-size:16px!important;line-height:1.7!important;color:var(--muted)}
.issue-tree-root{margin:26px auto 0;padding:16px 19px;max-width:520px;text-align:center;background:#173451;color:white;font:600 16px/1.6 Manrope,sans-serif;border-radius:5px;position:relative}
.issue-tree-root:after{content:'';position:absolute;left:50%;bottom:-22px;height:22px;border-left:1px solid #9db4c4}
.issue-tree-branches{display:flex;gap:16px;align-items:flex-start;padding-top:42px;position:relative}
.issue-tree-branches:before{content:'';position:absolute;top:21px;left:var(--tree-edge);right:var(--tree-edge);border-top:1px solid #9db4c4}
.issue-tree-branch{flex:1;min-width:0;position:relative}
.issue-tree-branch:before{content:'';position:absolute;top:-21px;left:50%;height:21px;border-left:1px solid #9db4c4}
.issue-tree-branch>button{display:flex;align-items:center;justify-content:space-between;gap:9px;width:100%;min-height:78px;padding:13px 14px;border:1px solid #b5ccd4;border-radius:5px;background:#f1f7f8;color:#173451;text-align:left;font:600 14px/1.5 Manrope,sans-serif;cursor:pointer}
.issue-tree-branch>button:hover,.issue-tree-branch>button[aria-expanded=true]{background:#deeeed;border-color:#087f83}
.tree-toggle{font-size:20px;color:var(--teal);flex-shrink:0}
.issue-tree-detail{padding:14px 1px 0;font-size:15px;line-height:1.7;color:var(--muted)}
.issue-tree-detail>p{font-size:15px;line-height:1.7}.issue-tree-detail ul{list-style:none;padding:0;margin:13px 0 0}.issue-tree-detail li{padding:13px 0;border-top:1px solid var(--line)}
.issue-tree-detail strong,.issue-tree-detail span{display:block}.issue-tree-detail strong{color:var(--ink);font-weight:600;margin-bottom:5px}
.tree-footnote{font-size:13px!important;line-height:1.7;color:var(--muted);margin:23px 0 0!important}
.worked-example>header h2{font-size:27px;line-height:1.35;margin:0 0 14px}.worked-example>header p{font-size:18px;line-height:1.8;color:var(--muted)}
.example-stage-nav{display:flex;gap:7px;flex-wrap:wrap;margin:27px 0 20px}
.example-stage-nav button{padding:9px 13px;background:white;border:1px solid #d4dfe6;border-radius:4px;font:600 12px/1.5 Manrope,sans-serif;text-align:left;color:#50657a;cursor:pointer}
.example-stage-nav button[aria-current=step]{background:#173451;border-color:#173451;color:#fff}.example-stage-nav button.studied:not([aria-current]){background:#eef7f4;border-color:#b9d8cd;color:#25665b}
.example-stage{background:#fff;border:1px solid var(--line);padding:28px;min-height:245px;border-radius:6px}
.example-stage h3{font-size:22px;margin:0 0 16px}.example-stage p{font-size:18px;line-height:1.85;color:#3f566e;margin:0 0 20px}.example-stage .example-pause{font-size:16px;color:var(--muted)}
.example-calculation{padding:17px 20px;background:#edf4f7;color:#173451;border-left:3px solid #92b3c6;white-space:pre-line;font-size:18px;line-height:1.8;overflow-wrap:anywhere;font-variant-numeric:tabular-nums}
.example-navigation{display:flex;align-items:center;justify-content:space-between;gap:16px;margin:17px 0 30px}.example-navigation>span{color:var(--muted);font-size:13px}
.example-conclusion{padding:23px 0;border-top:1px solid var(--line)}.example-conclusion h3{font-size:21px;margin-bottom:12px}.example-conclusion p{font-size:18px;line-height:1.85}
.example-trap{margin-top:23px;padding:20px 23px;background:#faf5e9;border-left:3px solid #c6a665}.example-trap h3{font-size:17px}.example-trap p{font-size:16px;margin-bottom:0;line-height:1.8}
.lesson-calculator{margin:34px 0;padding:26px;background:white;border:1px solid var(--line);border-radius:6px}
.calculator-inputs{display:grid;grid-template-columns:1fr 1fr;gap:17px;margin:23px 0}.calculator-inputs .field{margin:0;font-size:13px;line-height:1.6}.calculator-inputs input{font-size:17px;font-variant-numeric:tabular-nums}.calculator-inputs>button{justify-self:start}
.calculator-results{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;padding:20px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.calculator-results span{display:block;font-size:13px;color:var(--muted);line-height:1.5}.calculator-results strong{display:block;font:650 23px/1.5 Manrope,sans-serif;color:var(--ink);margin-top:7px;overflow-wrap:anywhere}.calculator-results small{display:block;color:#9b4941;font-size:12px;line-height:1.6;margin-top:7px}
.calculator-explanation{font-size:14px!important;line-height:1.8;color:var(--muted);margin:18px 0 0!important}.calculator-error{color:#a33b3b!important;font-size:14px!important}
.lesson-practice-links{display:grid;gap:10px;margin:24px 0}.lesson-practice-links a{display:block;padding:14px 17px;border:1px solid var(--line);border-radius:4px;color:var(--teal);background:#fff;text-decoration:none;font-weight:600}.lesson-practice-links a:hover{border-color:var(--teal)}
@media(max-width:1000px){.issue-tree-branches{gap:10px}.issue-tree-branch>button{font-size:13px;padding:11px}.lesson-tree{padding:22px}.calculator-results strong{font-size:21px}}
@media(max-width:600px){.lesson-format-tabs button{font-size:12px;padding:13px 11px}.lesson-objectives{padding:18px}.lesson-objectives ul{font-size:15px}.lesson-reading h2{font-size:22px}.lesson-reading p{font-size:17px;line-height:1.85}.issue-tree-branches{display:grid;padding:20px 0 0 16px;gap:13px;border-left:1px solid #9db4c4;margin:0 0 0 12px}.issue-tree-branches:before,.issue-tree-root:after{display:none}.issue-tree-branch:before{top:32px;left:-16px;width:16px;height:0;border-left:0;border-top:1px solid #9db4c4}.issue-tree-branch>button{min-height:64px;font-size:14px}.issue-tree-root{font-size:15px;text-align:left}.lesson-tree{padding:19px 16px}.example-stage{padding:22px 19px}.example-stage p,.example-conclusion p{font-size:17px}.example-stage-nav{gap:6px}.example-stage-nav button{font-size:11px}.example-calculation{font-size:16px;padding:14px}.calculator-inputs{grid-template-columns:1fr}.calculator-results{grid-template-columns:1fr}.calculator-results>div{display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap}.calculator-results strong{margin:0;font-size:22px}.calculator-results span{max-width:55%;align-self:center}.lesson-calculator{padding:22px 18px}.worked-example>header h2{font-size:24px}.example-navigation{gap:7px}.example-navigation .btn{font-size:12px}}

.course-search{display:flex;align-items:center;gap:16px;flex-wrap:wrap;margin:28px 0}.course-search label{font-size:14px;font-weight:650}.course-search input{font:400 16px "Source Sans 3",sans-serif;padding:12px 15px;border:1px solid #c7d5e1;background:#fff;border-radius:5px;width:340px;max-width:100%;box-sizing:border-box}.course-search span{font-size:14px;color:var(--muted)}.curriculum-module[hidden],.module-lesson[hidden]{display:none!important}