@charset "UTF-8";
:root{--ink:#142b43;--muted:#536579;--blue:#174bc0;--teal:#007f75;--paper:#f4f7fb;--line:#dce4ee;--white:#fff;--radius:18px}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0!important;padding:0!important;background:var(--paper)!important;color:var(--ink);font:17px/1.65 "Segoe UI",Arial,sans-serif!important;text-align:left!important}a{color:var(--blue);text-underline-offset:4px}a:hover{text-decoration:underline}button,input,select,textarea{font:inherit}button,[role=button],summary{cursor:pointer}button,.button{min-height:44px;border:1px solid var(--line);border-radius:9px;padding:10px 18px;background:var(--blue);color:white;font-weight:650;text-decoration:none;display:inline-block}button:hover,.button:hover{filter:brightness(.94)}button:disabled{cursor:default;filter:none}a:focus-visible,button:focus-visible,summary:focus-visible,[tabindex]:focus-visible,input:focus-visible{outline:3px solid #d67600;outline-offset:4px}img,video{max-width:100%;height:auto}table{max-width:100%;border-collapse:collapse}td,th{padding:10px;vertical-align:top}h1,h2,h3{line-height:1.2;letter-spacing:-.025em;color:var(--ink)}h1{font-size:clamp(2rem,4vw,3.25rem)}h2{font-size:clamp(1.5rem,3vw,2rem)}h3{font-size:1.2rem}p{margin:0 0 1.1em}li{margin-bottom:.4em}.skip-link{position:absolute;top:-100px;left:16px;z-index:100;padding:12px;background:#fff}.skip-link:focus{top:12px}.site-header{background:white;border-bottom:1px solid var(--line)}.header-inner{max-width:1240px;margin:auto;min-height:104px;padding:20px 32px;display:flex;justify-content:space-between;align-items:center;gap:20px}.brand{display:flex;align-items:center;gap:13px;text-decoration:none;color:var(--ink);font-size:29px;font-weight:750;letter-spacing:-1px}.brand:hover{text-decoration:none}.brand small{display:block;font-size:10px;letter-spacing:1.8px;color:var(--muted);font-weight:650}.brand-mark{height:48px;width:48px;border-radius:14px;background:var(--ink);color:white;display:flex;align-items:center;justify-content:center;font-size:31px}.brand-mark span{color:#5ee0c2;font-size:25px}.header-cta{font-size:14px;font-weight:650;background:#e8f5f1;color:#006b60;padding:10px 15px;border-radius:8px;white-space:nowrap}.header-cta span{padding-left:15px}.site-nav{background:#fff;border-bottom:1px solid var(--line);position:relative;z-index:20}.nav-inner{max-width:1240px;margin:auto;display:flex;align-items:stretch;padding:0 20px;gap:2px}.home-link,.nav-group summary{padding:16px 12px;font-size:14px;font-weight:600;color:var(--muted);text-decoration:none;list-style:none}.nav-group summary::-webkit-details-marker{display:none}.nav-group summary:after{content:'⌄';margin-left:8px;color:#7b8796}.nav-group{position:relative}.nav-group[data-current],.home-link[aria-current]{color:var(--blue);box-shadow:inset 0 -3px var(--blue)}.nav-group[open] summary{background:#edf3fd;color:var(--blue)}.nav-panel{position:absolute;top:100%;left:0;min-width:220px;padding:8px;background:white;border:1px solid var(--line);border-radius:0 0 12px 12px;box-shadow:0 15px 30px #142b4317}.nav-panel a{display:block;padding:10px 12px;font-size:15px;color:var(--ink);border-radius:6px;text-decoration:none}.nav-panel a:hover,.nav-panel a[aria-current]{background:#edf3fd;color:var(--blue)}main{min-height:65vh;outline:none}.page-heading{max-width:1160px;margin:0 auto;padding:44px 32px 28px}.page-heading h1{margin:10px 0 14px}.page-heading>p:not(.eyebrow){color:var(--muted)}.eyebrow{font-size:12px;font-weight:750;letter-spacing:2px;color:var(--teal);margin:0}.topic-nav{display:flex;flex-wrap:wrap;gap:8px;margin-top:24px}.topic-nav a{border:1px solid var(--line);border-radius:7px;padding:7px 13px;font-size:14px;color:var(--muted);background:white;text-decoration:none}.topic-nav a[aria-current]{color:white;background:var(--ink);border-color:var(--ink)}.lesson{max-width:1096px;margin:0 auto 56px;padding:32px;background:white;border:1px solid var(--line);border-radius:var(--radius);overflow-wrap:anywhere}.lesson>.container{width:auto!important;max-width:100%!important;height:auto!important;margin:0!important;padding:0!important;background:transparent!important;box-shadow:none!important;text-align:left}.lesson h1{font-size:2rem}.lesson p,.lesson li{line-height:1.7}.lesson center{text-align:center}.lesson center p{text-align:left}.lesson .flashcards-container{display:flex;flex-wrap:wrap;justify-content:center;gap:24px}.lesson .card-wrapper{max-width:100%;flex-shrink:1}.lesson .card-front,.lesson .card-back{box-sizing:border-box}.lesson .card-wrapper[aria-pressed=true]{outline:2px solid var(--teal)}.lesson .card-image{object-fit:contain}.lesson .options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.lesson .option{width:100%;color:var(--ink);background:#f0f4fb!important;border:2px solid var(--line);font-size:17px;text-align:left;font-weight:500}.lesson .option.correct{border-color:#008366;background:#e3f5ed!important}.lesson .option.incorrect{border-color:#b52b40;background:#ffedf0!important}.quiz{max-width:780px;margin:auto}.quiz-meta{display:flex;gap:16px;flex-wrap:wrap;justify-content:space-between;font-size:14px;color:var(--muted)}.quiz .question-image{display:block;width:auto;max-width:100%;max-height:280px;object-fit:contain;margin:20px auto}.quiz .question{font-size:1.45rem;margin:20px 0}.quiz-feedback{min-height:44px;margin:16px 0;font-weight:650}.quiz-actions{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.quiet-button{background:white;color:var(--ink)}.quiz progress{width:100%;height:8px;accent-color:var(--teal);margin:20px 0}.quiz-results{padding:24px;background:#eef7f5;border-radius:12px}.quiz-review{padding:18px 0;border-bottom:1px solid var(--line)}.quiz-review p{margin:.4em 0}.notice{padding:20px 24px;border-left:4px solid var(--teal);background:#edf7f5;border-radius:0 10px 10px 0;margin:24px 0}.notice p:last-child{margin-bottom:0}.source-note{font-size:14px;color:var(--muted);border-top:1px solid var(--line);padding-top:20px;margin-top:32px}.revision-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.revision-card{padding:24px;border:1px solid var(--line);border-radius:12px}.revision-card h2{margin-top:0;font-size:1.35rem}.lesson .draggable{max-width:100%;color:var(--ink)}.lesson [aria-pressed=true].draggable{outline:3px solid var(--blue);outline-offset:3px}.lesson .dropzone{color:var(--ink);border-color:#76889e}.activity-instructions{padding:16px;background:#edf3fd;border-radius:10px}.activity-status{font-weight:650;min-height:30px}.lesson .center-wrapper{overflow-x:auto;justify-content:flex-start!important}.lesson .diagram-container{flex-shrink:0}.lesson .options-wrapper{max-width:100%}.lesson iframe{max-width:100%}.site-footer{max-width:1240px;margin:auto;padding:32px;display:flex;align-items:center;justify-content:space-between;gap:24px;border-top:1px solid var(--line);color:var(--muted);font-size:13px}.footer-brand{font-size:22px;font-weight:750;color:var(--ink);text-decoration:none}.site-footer p{margin:5px 0}.site-footer>a{white-space:nowrap}.home-content{max-width:1240px;margin:auto;padding:44px 32px 64px}.hero{display:grid;grid-template-columns:1.25fr 1fr;gap:44px;align-items:center;min-height:380px;padding:18px 0 52px}.hero h1{font-size:clamp(2.6rem,5.5vw,4.7rem);line-height:1.06;margin:20px 0;max-width:700px;letter-spacing:-.055em}.hero h1 span{color:var(--blue)}.hero-copy>p:not(.eyebrow){max-width:540px;color:var(--muted);font-size:18px}.hero-actions{display:flex;flex-wrap:wrap;align-items:center;gap:20px;margin-top:28px}.text-link{font-weight:650;font-size:15px}.study-map{background:var(--ink);border-radius:24px;color:white;padding:30px;position:relative;overflow:hidden;box-shadow:0 20px 45px #142b431c}.study-map:before{content:'';width:220px;height:220px;position:absolute;right:-85px;top:-100px;border:40px solid #315576;border-radius:50%;pointer-events:none}.map-label{font-size:11px;letter-spacing:2px;color:#a4c0da;margin-bottom:20px}.study-map h2{color:white;font-size:1.5rem;margin:0 0 22px}.study-step{display:flex;gap:16px;align-items:center;margin:18px 0;position:relative}.step-num{color:#72e4cb;border:1px solid #42617c;border-radius:50%;width:38px;height:38px;display:grid;place-items:center;font-size:13px;flex-shrink:0}.study-step strong{display:block;font-size:16px}.study-step small{display:block;color:#b8cbdc;font-size:13px}.map-foot{border-top:1px solid #35516b;padding-top:18px;margin-top:22px;font-size:12px;color:#b8cbdc}.section-intro{display:flex;justify-content:space-between;gap:20px;align-items:end;margin:20px 0 24px}.section-intro h2{margin:6px 0}.section-intro p{color:var(--muted);font-size:15px;margin:0}.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.topic-card{background:white;border:1px solid var(--line);border-radius:var(--radius);padding:26px;display:flex;flex-direction:column;position:relative;transition:transform .15s,border-color .15s}.topic-card:hover{transform:translateY(-3px);border-color:#a8bfe6}.topic-number{font-size:12px;font-weight:700;color:var(--teal);letter-spacing:1px}.topic-card h3{margin:16px 0 10px;font-size:1.3rem}.topic-card p{color:var(--muted);font-size:15px;flex:1}.card-links{display:flex;gap:16px;font-size:14px;font-weight:650;margin-top:12px}.topic-card.est-card{background:#e6f3ef;border-color:#bddfd3}.est-banner{margin-top:38px;padding:30px;background:var(--ink);border-radius:var(--radius);color:white;display:flex;align-items:center;justify-content:space-between;gap:30px}.est-banner h2{color:white;margin:7px 0;font-size:1.6rem}.est-banner p{color:#bdd0e1;margin:0;font-size:15px}.est-banner .eyebrow{color:#72e4cb}.est-banner .button{background:white;color:var(--ink);white-space:nowrap}.empty-image{display:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
@media(max-width:1000px){.nav-inner{flex-wrap:wrap}.nav-group summary,.home-link{padding:12px 10px}.nav-group:last-child .nav-panel{left:auto;right:0}.lesson{margin-left:24px;margin-right:24px}.hero{gap:24px}.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:640px){.header-inner{padding:18px 20px;min-height:88px}.brand{font-size:25px}.brand small{font-size:8px;letter-spacing:1px}.brand-mark{width:40px;height:40px;font-size:27px}.header-cta{display:none}.nav-inner{padding:8px 12px;gap:4px}.home-link{width:100%;padding:8px}.nav-group{width:calc(50% - 2px)}.nav-group summary{padding:8px;font-size:13px}.nav-panel{position:static;min-width:0;border-radius:8px;box-shadow:none}.nav-panel a{font-size:13px;padding:8px}.home-content{padding:28px 20px 40px}.hero{grid-template-columns:1fr;padding-bottom:28px;gap:28px;min-height:0}.hero h1{font-size:2.9rem}.hero-copy>p:not(.eyebrow){font-size:16px}.study-map{padding:24px}.topic-grid,.revision-grid{grid-template-columns:1fr}.section-intro{display:block}.section-intro>p{margin-top:12px}.topic-card{padding:22px}.est-banner{display:block;padding:24px}.est-banner .button{margin-top:22px}.page-heading{padding:28px 20px 22px}.page-heading h1{font-size:2rem}.lesson{padding:20px;margin:0 12px 32px;border-radius:12px}.lesson .options{grid-template-columns:1fr}.lesson .card-wrapper{width:100%;max-width:100%}.site-footer{padding:24px 20px;align-items:start;flex-wrap:wrap}.lesson table{display:block;overflow-x:auto}.lesson h1{font-size:1.6rem}.lesson .dropzone{margin:6px}.lesson .draggable{margin:6px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition:none!important;animation:none!important}}
@media print{.site-nav,.topic-nav,.header-cta,.skip-link,.site-footer{display:none}.site-header{border:0}.lesson{max-width:none;margin:0;border:0;padding:0;box-shadow:none}.page-heading{padding:12px 0}body{background:white!important}.revision-grid{display:block}.revision-card{break-inside:avoid;margin-bottom:12px}.notice{border:1px solid #777}.brand{font-size:22px}button{display:none}}

/* Accessible reveal cards and matching activities. */
.flashcard{background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden;align-self:start}.flashcard summary{padding:22px;list-style:none;display:block}.flashcard summary::-webkit-details-marker{display:none}.flashcard[open]{border-color:#77b6aa}.flashcard-index{display:block;color:var(--teal);font-size:11px;font-weight:750;letter-spacing:1.5px}.flashcard-prompt{display:block;margin:14px 0;font-weight:650;line-height:1.5}.flashcard-prompt img{display:block;max-height:180px;max-width:100%;width:auto;height:auto;object-fit:contain;margin:12px auto;position:static}.flashcard-hint{display:block;color:var(--blue);font-size:13px;font-weight:600}.flashcard[open] .flashcard-hint{font-size:0}.flashcard[open] .flashcard-hint:after{content:'Select to hide answer';font-size:13px}.flashcard-answer{padding:22px;border-top:1px solid var(--line);background:#f3f8f7}.flashcard-answer p:last-child{margin-bottom:0}.flashcard-answer img{position:static;display:block;max-height:360px;max-width:100%;width:auto;height:auto;margin:auto;object-fit:contain}.flashcard-answer li{font-size:16px}.matching-tray,.matching-destinations{display:flex;flex-wrap:wrap;gap:16px;margin:24px 0}.matching-tray .draggable{background:#eef3fc;border:1px solid #b8c8e1;border-radius:10px;width:280px;padding:16px;font-size:15px;line-height:1.5;cursor:grab}.match-target{flex:1 1 250px;min-width:0}.match-target h3{font-size:17px}.match-target .dropzone{min-height:150px;border:2px dashed #8395ac;border-radius:10px;padding:10px}.match-target .dropzone .draggable{background:#eef3fc;padding:12px;border-radius:8px;font-size:15px}.lesson .gallery-wrapper{max-width:100%;margin:24px auto}.lesson .gallery-container img{max-width:none}.lesson #components{gap:8px}.lesson #dropzones{display:flex;justify-content:center;flex-wrap:wrap}.lesson #dropzones .dropzone{line-height:1.4;display:flex;align-items:center;justify-content:center;min-height:120px;height:auto}.lesson .diagram-container{width:800px;min-width:800px}.lesson .diagram-container .background-image{max-width:none}.lesson .dropzone .draggable{max-width:100%}

.lesson iframe[src*="youtube"]{aspect-ratio:16/9;width:100%;max-width:720px;height:auto}.lesson .gallery-wrapper img{object-fit:contain}

.est-table-wrap{overflow-x:auto;margin:20px 0 28px}.est-table-wrap table{width:100%;font-size:15px}.est-table-wrap th{background:#eaf0f8;text-align:left}.est-table-wrap td,.est-table-wrap th{border:1px solid var(--line);padding:12px}.est-table-wrap tbody tr:nth-child(even){background:#f7f9fc}.lesson h4{font-size:1.05rem;margin:24px 0 10px;color:var(--ink)}