.study-hero{display:grid;grid-template-columns:1.3fr 1fr;gap:65px;padding:90px 0 80px;align-items:center}.study-hero h1{font-size:clamp(2.8rem,5.6vw,5.1rem);line-height:1.02;letter-spacing:-.065em;margin:20px 0 24px}.study-hero h1 em{font-style:normal;color:var(--accent)}.study-hero .intro{font-size:1.15rem;margin-bottom:30px;max-width:540px}.progress-card,.quiz-card{border:1px solid var(--line);border-radius:24px;background:var(--surface);padding:32px}.progress-card h2{font-size:2rem;letter-spacing:-.04em;line-height:1.15;margin:26px 0}.stat-row{display:flex;gap:32px;margin:26px 0}.stat-row strong{display:block;font-size:1.8rem;letter-spacing:-.04em}.stat-row span{font-size:.8rem;color:var(--muted);display:block;margin-top:8px}.progress-card p{font-size:.83rem;color:var(--muted);line-height:1.6}progress{width:100%;height:8px;accent-color:var(--accent)}.topic-section{padding:32px 0 65px}.topic-section .section-heading h2{font-size:2.5rem;max-width:550px}#topic-list{display:grid;gap:14px}.topic{border:1px solid var(--line);border-radius:18px;background:var(--surface);overflow:hidden}.topic summary{display:flex;align-items:center;gap:22px;padding:25px;cursor:pointer;list-style:none}.topic summary::-webkit-details-marker{display:none}.topic-number{font-size:.9rem;color:var(--accent);font-weight:750}.topic-title{flex:1}.topic-title strong{display:block;font-size:1.35rem;letter-spacing:-.035em}.topic-title small{display:block;margin-top:6px;color:var(--muted);font-size:.9rem;font-weight:400}.topic-check{font-size:.76rem;color:var(--accent);font-weight:700}.topic summary:after{content:'+';font-size:1.7rem;color:var(--accent)}.topic[open] summary:after{content:'−'}.lesson-content{padding:0 25px 28px 65px;border-top:1px solid var(--line)}.lesson-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:25px;padding:18px 0}.lesson-grid h3{font-size:1.12rem;letter-spacing:-.02em}.lesson-grid p{font-size:.95rem;color:var(--muted);line-height:1.75}.lesson-actions{display:flex;align-items:center;gap:15px;flex-wrap:wrap}.lesson-source{font-size:.8rem;color:var(--muted);margin-top:20px}.practice-section{border-top:1px solid var(--line);padding:70px 0}.practice-section h2{font-size:clamp(2rem,4vw,3rem);letter-spacing:-.05em}.practice-section .intro{font-size:1.05rem;max-width:720px}.practice-actions{display:flex;flex-wrap:wrap;gap:12px;margin:25px 0}.practice-actions .button,.lesson-actions .button{font-size:.9rem;cursor:pointer}.button:disabled{opacity:.5;cursor:not-allowed}.text-button{background:none;color:var(--accent);border:0;padding:10px 0;font:inherit;text-decoration:underline;text-underline-offset:4px;cursor:pointer}.quiz-card{max-width:850px;margin-top:28px}.quiz-meta{display:flex;justify-content:space-between;gap:18px;font-size:.8rem;color:var(--muted);margin-bottom:15px}.quiz-card h3{font-size:1.55rem;line-height:1.35;letter-spacing:-.03em;margin:28px 0}.options{display:grid;gap:12px;border:0;padding:0;margin:0}.option{display:flex;gap:14px;align-items:center;cursor:pointer;border:1px solid var(--line);border-radius:12px;padding:17px;background:var(--bg);font-size:1rem;line-height:1.5}.option:has(input:checked){border-color:var(--accent);outline:1px solid var(--accent)}.option input{accent-color:var(--accent);width:18px;height:18px;flex-shrink:0}.option.correct{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 9%,var(--surface))}.option.wrong{border-style:dashed}.answer-feedback{padding:20px;border-left:3px solid var(--accent);margin:22px 0;background:var(--bg);border-radius:0 12px 12px 0;line-height:1.7}.answer-feedback p{margin:6px 0 0}.quiz-controls{display:flex;gap:18px;align-items:center;flex-wrap:wrap;margin-top:24px}.quiz-controls .button{cursor:pointer}.score{font-size:4rem;font-weight:800;letter-spacing:-.06em;color:var(--accent);margin:20px 0}.result-list{padding-left:24px;line-height:1.6}.result-list li{margin-bottom:18px}.study-about{padding:42px 0 65px;border-top:1px solid var(--line);max-width:850px}.study-about p{color:var(--muted);line-height:1.8}.study-about details{margin:25px 0}.study-about summary{cursor:pointer;font-weight:700}.study-about li{margin:14px 0}.privacy-note{font-size:.85rem}.study-about h2{letter-spacing:-.035em;font-size:1.7rem}[hidden]{display:none!important}:focus-visible{outline:3px solid var(--accent);outline-offset:5px}#topics,#practice{scroll-margin-top:30px}@media(max-width:800px){.study-hero{grid-template-columns:1fr;gap:32px;padding:48px 0}.progress-card{padding:26px}.lesson-grid{grid-template-columns:1fr;gap:0}.lesson-content{padding:0 22px 25px}.topic summary{padding:22px;gap:14px}.topic-title small{font-size:.82rem}.topic-check{max-width:60px;text-align:right}.practice-section{padding:45px 0}.quiz-card{padding:22px}.quiz-card h3{font-size:1.3rem}.topic-section .section-heading h2{font-size:2rem}}@media(max-width:450px){.study-hero h1{font-size:2.9rem}.practice-actions{flex-direction:column}.practice-actions .button{width:100%;justify-content:center}.topic-title strong{font-size:1.15rem}.topic-number{display:none}.stat-row{gap:22px}.quiz-meta{font-size:.75rem}}