:root{--ink:#233c36;--green:#244f46;--muted:#68756f;--paper:#f7f8f4;--line:#dce3dc;--gold:#b48642;--pale:#eaf0e8}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.6 system-ui,-apple-system,Segoe UI,sans-serif}a{color:var(--green)}button,input,select{font:inherit}button,.button{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:46px;padding:10px 20px;border:1px solid var(--green);border-radius:7px;background:var(--green);color:white;text-decoration:none;cursor:pointer;font-weight:600}button.secondary,.button.secondary{background:white;color:var(--green);border-color:var(--line)}button:hover,.button:hover{filter:brightness(.93)}:focus-visible{outline:3px solid #b17b25;outline-offset:4px}header{height:108px;display:flex;justify-content:space-between;align-items:center;padding:20px 4%;background:white;border-bottom:1px solid 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var(--line);border-radius:8px;background:white}fieldset{min-width:0}.question legend{font-weight:650;padding:0 6px}.option{display:flex;align-items:center;gap:12px;padding:10px;border:1px solid var(--line);border-radius:6px;margin:9px 0;cursor:pointer}.option input{width:18px;height:18px;accent-color:var(--green)}.question .toolbar{margin-bottom:0}.question button{font-size:13px;padding:7px 13px}.english{font-family:Georgia,serif;font-size:21px;line-height:1.9}.vocabulary{display:grid;grid-template-columns:1fr 1fr;gap:10px}.vocabulary div{padding:14px;background:#f0f3ed;border-radius:6px}.vocabulary small{display:block;color:var(--muted)}.result{padding:18px;border-radius:7px;background:var(--pale);margin-top:15px}.wrong{background:#f9ece5}.good{color:#275a3e;font-weight:700}.formula{padding:15px;background:var(--pale);border-radius:6px;margin:10px 0}.formula small{display:block;color:#586b5b;font-weight:650}.structure{margin-bottom:20px}.structure ul{padding-left:22px}.actions{display:flex;gap:12px;flex-wrap:wrap;margin:22px 0}footer{border-top:1px solid var(--line);font-size:12px;color:var(--muted);margin-top:45px;padding-top:24px}footer small{font-size:11px}.skip{position:fixed;top:-100px;background:white;padding:10px;z-index:10}.skip:focus{top:0}iframe{width:100%;height:75vh;border:1px solid var(--line);background:white}.hidden{display:none}@media(min-width:1250px){main{padding-left:6%;padding-right:6%}}@media(max-width:760px){header{height:90px;padding:15px 20px}.brand{font-size:18px}.brand small{font-size:7px}.goal{display:none}.layout{display:block}aside{padding:12px 14px;border-right:0;border-bottom:1px solid var(--line)}nav{display:flex;gap:4px;overflow:auto}nav a{white-space:nowrap;padding:10px;font-size:13px;gap:5px}.nav-label,.side-note,.edition{display:none}main{padding:25px 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@media(max-width:760px){nav{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));overflow:visible}nav a{white-space:normal;line-height:1.35;justify-content:center;text-align:center}nav a:last-child{grid-column:span 2}}
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@media(max-width:760px){nav a:last-child{grid-column:auto}main{padding-inline:16px}.question legend{max-width:100%;overflow-wrap:anywhere}.table-scroll th,.table-scroll td{padding:9px 12px}iframe{height:79vh;min-height:490px}}

/* El visor conserva una sola superficie de desplazamiento al ajustar el alto de la clase. */
.lesson-frame{min-height:0;scroll-margin-top:12px}
.lesson-full>header,.lesson-full .layout>aside,.lesson-full main>footer{display:none}
.lesson-full .layout{display:block;max-width:none}
.lesson-full main{padding:0}
.lesson-full .lesson-frame{border:0;border-radius:0;scroll-margin-top:82px}
.lesson-toolbar{position:sticky;top:0;z-index:2;display:flex;gap:8px;flex-wrap:wrap;padding:8px 12px;background:white;border-bottom:1px solid var(--line)}
.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
@media(max-width:760px){.lesson-toolbar .button{font-size:.875rem;padding-inline:10px}}