:root{--skills-navy:#13263e}body{background:#f4f7fa}.topbar{background:var(--skills-navy);border-bottom-width:2px}.skills-main{max-width:1040px}.skills-main h2{font-size:25px;line-height:1.3;margin:0 0 14px}.skills-main h3{font-size:22px;line-height:1.3;margin:0}.lesson-heading{position:relative;margin-bottom:30px}.lesson-heading .eyebrow{margin-bottom:9px}.lesson-heading h1{margin-bottom:18px}.jump-link{font-size:16px;font-weight:650;color:#1768ac}.worked-example,.practice{background:white;border:1px solid #d4dee8;border-radius:15px;padding:30px;margin-bottom:28px}.worked-example>p{max-width:760px;margin:0 0 18px}.worked-grid,.question-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:34px;align-items:center}.diagram{margin:0;min-width:0;position:relative}.equipment-svg{width:100%;height:auto;display:block;max-height:430px;overflow:visible}.diagram figcaption{font-size:16px;line-height:1.5;color:#43576b;margin:10px auto 0;max-width:400px}.worked-diagram{border-radius:12px;background:#f8fafc;padding:10px}.worked-steps ol{margin:0;padding-left:27px;display:grid;gap:19px}.worked-steps li{padding-left:7px}.worked-steps li::marker{font-weight:750;color:#1768ac}.worked-steps li strong,.worked-steps li span{display:block}.worked-steps li span{margin-top:5px}.remember{background:#edf4fa;border-left:3px solid #1768ac;border-radius:0 8px 8px 0;padding:13px 16px;font-size:16px;margin:24px 0 0}.practice{scroll-margin-top:20px}.practice-header{display:flex;justify-content:space-between;align-items:baseline;gap:15px;flex-wrap:wrap}.practice-header p{color:#52677a;margin:0;font-size:15px}.question-picker{display:flex;gap:7px;flex-wrap:wrap;border-bottom:1px solid #e0e7ee;padding-bottom:21px;margin:10px 0 23px}.question-picker button{width:44px;min-height:44px;padding:6px;border:1px solid #bac8d6;background:white;color:#13263e;border-radius:7px;font-size:16px;font-weight:650}.question-picker button[aria-current]{background:#13263e;color:white;border-color:#13263e}.question-picker button.done:not([aria-current]){background:#e7f4ec;border-color:#36825a;color:#185c37}.question-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:12px}.challenge{font-size:14px;padding:4px 9px;border:1px solid #bac8d6;border-radius:6px;color:#43576b}.question-prompt{margin:0 0 20px}.question-controls label{display:block;font-size:16px;font-weight:650;margin-bottom:7px}.input-unit{display:flex;align-items:center;gap:12px;margin-bottom:20px}.input-unit input{width:150px;max-width:65%;min-height:48px;background:white;border:1.5px solid #8296aa;border-radius:7px;padding:8px 12px;font:20px/1.3 system-ui;color:#15283b}.input-unit input:focus{outline:3px solid #90bde2;outline-offset:2px}.input-unit input[aria-invalid=true]{border-color:#aa3131}.input-unit span{font-weight:650;font-size:18px}.skills-main button,dialog button{min-height:44px;border-radius:7px;font:650 16px/1.35 system-ui;padding:10px 17px;cursor:pointer;background:white;border:1px solid #a8b9c9;color:#13263e}.skills-main button.primary{background:#13263e;color:white;border-color:#13263e}.skills-main button:hover,dialog button:hover{background:#e9f0f6}.skills-main button.primary:hover{background:#264563}.skills-main button:disabled{opacity:.45;cursor:default}.skills-main button:focus-visible,dialog button:focus-visible{outline:3px solid #1676b4;outline-offset:3px}.skills-main .enlarge{display:block;margin:8px auto 0;font-size:14px;min-height:44px;padding:8px 14px}.skills-main .minus-key{padding:8px 14px;font-size:20px}.feedback:empty{display:none}.feedback{padding:13px 15px;background:#fff4e4;color:#633b0d;border:1px solid #d4a666;border-radius:8px;margin-top:16px;font-size:16px}.feedback.correct{background:#edf8f0;color:#185732;border-color:#93b8a0}.help-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:17px}.help-actions button{font-size:14px;padding:9px 12px}.hint,.solution{font-size:16px;line-height:1.6;border-left:3px solid #8fa5ba;padding:11px 14px;background:#f2f6fa;margin:14px 0 0}.question-navigation{display:flex;justify-content:space-between;gap:12px;margin-top:28px;border-top:1px solid #e0e7ee;padding-top:22px}.completion{margin-top:22px;padding:22px;border-radius:10px;background:#edf8f0;border:1px solid #93b8a0}.completion p{margin:12px 0 17px}.skill-lesson-link{display:flex;align-items:center;gap:18px;max-width:540px;padding:20px 24px;margin-top:27px;background:#13263e;border-radius:12px;color:white;text-decoration:none;font-size:20px;font-weight:650}.lesson-number{display:grid;place-items:center;min-width:42px;height:42px;border:1px solid #7c8fa5;border-radius:8px}.skill-lesson-link:hover{background:#264563}dialog{width:min(820px,calc(100% - 24px));max-height:95vh;border:1px solid #c2d0dd;border-radius:14px;padding:20px;color:#15283b;background:white;overflow:auto}dialog::backdrop{background:#13263ebf}.dialog-header{display:flex;align-items:center;justify-content:space-between;gap:20px}.dialog-header h2{font:700 21px/1.3 system-ui;margin:0}#large-diagram .equipment-svg{max-height:none;min-width:620px}#large-diagram{margin-top:12px;overflow:auto}.zoom-note{font:15px/1.5 system-ui;color:#52677a;margin:10px 0 0}.noscript-note{padding:16px;background:#fff4e4}.home-skills-link{display:block;width:max-content;margin:22px 0 0;color:#13263e;font-size:16px;font-weight:650;padding:7px 0;min-height:44px}
@media(max-width:700px){.worked-grid,.question-grid{grid-template-columns:minmax(0,1fr);gap:22px}.worked-example,.practice{padding:20px 17px}.equipment-svg{max-height:370px}.worked-diagram .equipment-svg{max-height:345px}.worked-diagram{max-width:410px;width:100%;margin:auto}.skills-main h2{font-size:23px}.lesson-heading{margin-bottom:24px}.worked-steps ol{gap:17px}.question-grid .diagram{max-width:440px;width:100%;margin:auto}.practice-header{gap:2px}.practice-header h2{margin-bottom:7px}.question-picker{gap:7px;margin-top:17px}.skills-main .question-picker button{padding:6px;width:40px;min-height:44px}.question-heading{margin-bottom:0}.question-prompt{margin-bottom:17px}.input-unit input{width:160px}.help-actions button{font-size:15px}.question-controls{padding-top:5px}.question-navigation{margin-top:22px}.skills-main h3{font-size:21px}.skill-lesson-link{padding:18px;font-size:19px}}
@media(max-width:360px){.worked-example,.practice{padding:17px 13px}.skills-main{width:calc(100% - 24px)}.skills-main .question-picker button{width:38px}.question-picker{gap:6px}}
@media print{.topbar,.jump-link,.question-picker,.question-navigation,.help-actions,.enlarge,.completion,dialog,button{display:none!important}.exercise[hidden]{display:block!important}.exercise{break-inside:avoid;margin-bottom:24px;padding-top:15px;border-top:1px solid #ccc}.worked-grid,.question-grid{grid-template-columns:1fr 1fr}.equipment-svg{max-height:280px}.practice,.worked-example{border:0;padding:0}.skills-main{width:100%;max-width:none}body{background:white}.feedback,.hint,.solution{display:none!important}.page-footer{margin-top:20px}}