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10px);margin:14px 0 0 10px;font-family:var(--font-sans);font-size:13px;color:var(--text-faint);background:transparent;border:1px solid var(--border);border-radius:var(--r);padding:8px 10px;cursor:pointer}.reset-btn:hover{color:var(--text);border-color:var(--border-strong)}.lesson-panel{background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r);padding:24px}.lesson-panel h2{font-size:24px;margin:8px 0 10px}.lesson-desc{color:var(--text-dim);margin:0;font-size:15.5px}.lesson-panel code{font-family:var(--font-mono);background:var(--bg-panel-2);border:1px solid var(--border);padding:1px 6px;border-radius:5px;color:var(--amber-soft);font-size:.9em}.concept-box,.pitfall-box{margin-top:16px;padding:12px 14px;border-radius:var(--r);background:var(--bg);border:1px solid var(--border)}.concept-box .concept-label,.pitfall-box .pitfall-label{font-size:13px;font-weight:600;color:var(--text);cursor:pointer;list-style:none;display:flex;align-items:center;justify-content:space-between}.concept-box summary::-webkit-details-marker,.pitfall-box summary::-webkit-details-marker{display:none}.concept-box summary:after,.pitfall-box summary:after{content:"+";font-family:var(--font-mono);color:var(--text-faint)}.concept-box[open] summary:after,.pitfall-box[open] summary:after{content:"-"}.pitfall-box{border-left:3px solid #d9a441}.pitfall-box .pitfall-label{color:#e6b865}.concept-box p,.pitfall-box p{margin:4px 0 0;font-size:14px;line-height:1.6;color:var(--text-dim)}.lesson-footer{display:flex;align-items:center;gap:12px;margin-top:18px;flex-wrap:wrap}.progress-label{font-family:var(--font-mono);font-size:12px;color:var(--text-faint);margin-left:auto}.hint-toggle{font-family:var(--font-sans);font-size:13.5px;font-weight:500;color:var(--text);background:transparent;border:1px solid var(--border-strong);border-radius:var(--r);padding:7px 12px;cursor:pointer}.hint-toggle:hover{background:var(--bg-panel-2)}.hint-box{display:none;margin-top:10px;font-family:var(--font-mono);font-size:13.5px;background:#080a09;border:1px solid var(--border);color:var(--amber-soft);padding:10px 14px;border-radius:var(--r)}.hint-box.show{display:block}.lesson-nav{display:flex;gap:10px;margin-top:20px;padding-top:16px;border-top:1px solid var(--border)}.nav-btn{font-family:var(--font-sans);font-size:14px;font-weight:600;background:transparent;color:var(--text-dim);border:1px solid var(--border-strong);border-radius:var(--r);padding:9px 16px;cursor:pointer;transition:background .2s var(--ease),color .2s,border-color .2s,transform .15s}.nav-btn:hover:not(:disabled){color:var(--text);background:var(--bg-panel-2)}.nav-btn:active:not(:disabled){transform:translateY(1px)}.nav-btn:disabled{opacity:.35;cursor:not-allowed}.nav-btn.primary{margin-left:auto}.nav-btn.primary.ready:not(:disabled){background:var(--amber);color:#07120b;border-color:var(--amber)}.nav-btn.primary.ready:not(:disabled):hover{background:#63ec96}.done-flag{font-size:13px;color:var(--amber);font-weight:600}.learn-about{max-width:780px;margin-top:96px}.learn-about h2{margin-top:0}@media(max-width:1240px){.learn-main{grid-template-columns:1fr}.learn-term{position:static}.learn-term .st-body{height:min(46vh,420px)}}@media(max-width:900px){.learn-layout{grid-template-columns:1fr}.learn-sidebar{position:static;order:2;max-height:320px;border:1px solid var(--border);border-radius:var(--r);padding:10px 4px 12px 0}.learn-main{order:1}.learn-about{margin-top:64px}}