:root{--bg:#f7f8fa;--bg-elevated:#fff;--text:#1b1f24;--text-dim:#5b6572;--border:#e3e6ea;--accent:#3b5bdb;--accent-soft:#e8ecfd;--success:#1f9d55;--success-soft:#e5f7ea;--danger:#d64545;--danger-soft:#fbe9e9;--code-bg:#f1f2f6;--radius:10px;--shadow:0 1px 3px #14141e0f, 0 1px 2px #14141e0a;--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light}@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--bg:#14171c;--bg-elevated:#1c2027;--text:#e7e9ec;--text-dim:#9aa3af;--border:#2a2f38;--accent:#7f9cff;--accent-soft:#232a45;--success:#3ecb72;--success-soft:#173626;--danger:#ef6a6a;--danger-soft:#3a2020;--code-bg:#20242c;--lightningcss-light: ;--lightningcss-dark:initial;color-scheme:dark}}:root[data-theme=dark]{--bg:#14171c;--bg-elevated:#1c2027;--text:#e7e9ec;--text-dim:#9aa3af;--border:#2a2f38;--accent:#7f9cff;--accent-soft:#232a45;--success:#3ecb72;--success-soft:#173626;--danger:#ef6a6a;--danger-soft:#3a2020;--code-bg:#20242c;--lightningcss-light: ;--lightningcss-dark:initial;color-scheme:dark}*{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;line-height:1.55}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.app-shell{min-height:100vh;display:flex}.sidebar{background:var(--bg-elevated);border-right:1px solid var(--border);flex:0 0 290px;width:290px;height:100vh;padding:18px 14px 40px;position:sticky;top:0;overflow-y:auto}.brand{align-items:center;gap:10px;padding:6px 8px 18px;font-size:1.05rem;font-weight:700;display:flex}.brand .logo{background:linear-gradient(135deg,var(--accent),#8a5cf6);color:#fff;border-radius:9px;justify-content:center;align-items:center;width:34px;height:34px;font-size:1.1rem;display:flex}.nav-module{margin-bottom:6px}.nav-module-btn{text-align:left;cursor:pointer;width:100%;color:var(--text);background:0 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8px;font-size:.85rem;display:flex}.nav-lesson:hover{background:var(--accent-soft);color:var(--text)}.nav-lesson.active{background:var(--accent-soft);color:var(--accent);font-weight:600}.nav-lesson .dot{background:var(--border);border-radius:50%;flex:0 0 7px;width:7px;height:7px}.nav-lesson.done .dot{background:var(--success)}.topbar{z-index:5;background:var(--bg);border-bottom:1px solid var(--border);align-items:center;gap:14px;padding:12px 22px;display:flex;position:sticky;top:0}.topbar-title{text-overflow:ellipsis;white-space:nowrap;flex:1;min-width:0;font-size:1rem;font-weight:700;overflow:hidden}.progress-pill{color:var(--text-dim);background:var(--bg-elevated);border:1px solid var(--border);border-radius:999px;align-items:center;gap:8px;padding:5px 10px;font-size:.78rem;display:flex}.progress-pill .bar{background:var(--border);border-radius:99px;width:80px;height:6px;overflow:hidden}.progress-pill .bar>span{background:var(--success);height:100%;display:block}.lang-toggle{border:1px solid var(--border);border-radius:8px;display:flex;overflow:hidden}.lang-toggle button{background:var(--bg-elevated);color:var(--text-dim);cursor:pointer;border:none;padding:6px 12px;font-size:.8rem;font-weight:700}.lang-toggle button.active{background:var(--accent);color:#fff}.menu-btn{border:1px solid var(--border);cursor:pointer;width:36px;height:36px;color:var(--text);background:0 0;border-radius:8px;font-size:1.05rem;display:none}.main{flex-direction:column;flex:1;min-width:0;display:flex}.content{width:100%;max-width:840px;margin:0 auto;padding:28px 26px 80px}.hero{padding:6px 0 26px}.hero h1{margin:0 0 8px;font-size:1.7rem}.hero p{color:var(--text-dim);max-width:640px;margin:0}.continue-card{background:var(--accent-soft);border:1px solid var(--border);border-radius:var(--radius);align-items:center;gap:14px;margin-top:18px;padding:16px 18px;display:flex}.continue-card .go-btn{background:var(--accent);color:#fff;cursor:pointer;white-space:nowrap;border:none;border-radius:8px;margin-left:auto;padding:9px 16px;font-size:.85rem;font-weight:700}.module-grid{grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:14px;margin-top:10px;display:grid}.module-card{background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius);cursor:pointer;box-shadow:var(--shadow);flex-direction:column;gap:8px;padding:16px;display:flex}.module-card:hover{border-color:var(--accent)}.module-card .top{align-items:center;gap:10px;display:flex}.module-card .top .icon{font-size:1.4rem}.module-card h3{margin:0;font-size:.98rem}.module-card p{color:var(--text-dim);flex:1;margin:0;font-size:.8rem}.mini-bar{background:var(--border);border-radius:99px;height:6px;overflow:hidden}.mini-bar>span{background:var(--success);height:100%;display:block}.module-card .meta{color:var(--text-dim);font-size:.72rem}.lesson-list-item{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg-elevated);cursor:pointer;align-items:center;gap:12px;margin-bottom:8px;padding:13px 14px;display:flex}.lesson-list-item:hover{border-color:var(--accent)}.lesson-list-item .num{background:var(--accent-soft);width:28px;height:28px;color:var(--accent);border-radius:50%;flex:0 0 28px;justify-content:center;align-items:center;font-size:.78rem;font-weight:700;display:flex}.lesson-list-item.done .num{background:var(--success-soft);color:var(--success)}.lesson-list-item .title{flex:1;font-size:.92rem;font-weight:600}.lesson-list-item .check{color:var(--success);font-size:1rem}.breadcrumb{color:var(--text-dim);margin-bottom:10px;font-size:.8rem}.lesson-header h1{margin:0 0 6px;font-size:1.5rem}.lesson-body{margin-top:18px;font-size:.97rem}.lesson-body h3{margin:26px 0 8px;font-size:1.12rem}.lesson-body h4{margin:20px 0 6px;font-size:1rem}.lesson-body p{margin:0 0 12px}.lesson-body ul,.lesson-body ol{margin:0 0 12px;padding-left:22px}.lesson-body li{margin-bottom:5px}.lesson-body pre{background:var(--code-bg);border:1px solid var(--border);border-radius:8px;margin:0 0 14px;padding:12px 14px;font-size:.85rem;overflow-x:auto}.lesson-body code{background:var(--code-bg);border-radius:5px;padding:2px 5px;font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.88em}.lesson-body pre code{background:0 0;padding:0}.lesson-body table{border-collapse:collapse;width:100%;margin:0 0 14px;font-size:.88rem}.lesson-body th,.lesson-body td{border:1px solid var(--border);text-align:left;padding:7px 10px}.lesson-body th{background:var(--bg-elevated)}.callout{border-left:3px solid var(--accent);background:var(--accent-soft);border-radius:0 8px 8px 0;margin:0 0 14px;padding:10px 14px;font-size:.9rem}.callout-warning{border-left-color:var(--danger);background:var(--danger-soft)}.callout-note{border-left-color:var(--text-dim);background:var(--code-bg)}.lesson-summary{color:var(--text-dim);border-bottom:1px solid var(--border);margin:0 0 6px;padding-bottom:14px;font-size:1rem;font-style:italic}.key-terms{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg-elevated);margin-top:30px;padding:18px 20px}.key-terms h3{margin:0 0 12px;font-size:1.05rem}.key-terms dl{margin:0}.key-term{margin-bottom:12px}.key-term:last-child{margin-bottom:0}.key-term dt{color:var(--accent);font-size:.9rem;font-weight:700}.key-term dd{color:var(--text);margin:2px 0 0;font-size:.88rem}.exercises{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg-elevated);margin-top:24px;padding:18px 20px}.exercises h3{margin:0 0 12px;font-size:1.05rem}.exercise-list{margin:0;padding-left:20px}.exercise-item{margin-bottom:14px;font-size:.9rem}.exercise-item:last-child{margin-bottom:0}.exercise-prompt{margin-bottom:6px}.hint-toggle{border:1px solid var(--border);color:var(--accent);cursor:pointer;background:0 0;border-radius:6px;padding:4px 9px;font-size:.75rem}.exercise-hint{color:var(--text-dim);background:var(--code-bg);border-radius:6px;margin-top:6px;padding:8px 10px;font-size:.85rem}.quiz-explanation{color:var(--text-dim);background:var(--code-bg);border-left:3px solid var(--accent);border-radius:6px;margin-top:8px;padding:8px 10px;font-size:.85rem}.lesson-nav{border-top:1px solid var(--border);justify-content:space-between;gap:10px;margin-top:34px;padding-top:18px;display:flex}.lesson-nav button{background:var(--bg-elevated);border:1px solid var(--border);cursor:pointer;color:var(--text);text-align:left;border-radius:8px;max-width:47%;padding:10px 16px;font-size:.85rem}.lesson-nav button:hover{border-color:var(--accent)}.lesson-nav button:disabled{opacity:.35;cursor:default}.lesson-nav .dir{color:var(--text-dim);margin-bottom:2px;font-size:.7rem;display:block}.mark-complete{align-items:center;gap:10px;margin-top:22px;display:flex}.mark-complete button{background:var(--success);color:#fff;cursor:pointer;border:none;border-radius:8px;padding:10px 18px;font-size:.85rem;font-weight:700}.mark-complete button.undo{background:var(--bg-elevated);color:var(--text-dim);border:1px solid var(--border)}.mark-complete .ok{color:var(--success);align-items:center;gap:6px;font-size:.85rem;font-weight:600;display:flex}.quiz{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg-elevated);margin-top:30px;padding:18px 20px}.quiz h3{margin:0 0 14px;font-size:1.05rem}.quiz-q{margin-bottom:18px}.quiz-q .q-text{margin-bottom:8px;font-size:.92rem;font-weight:600}.quiz-opt{border:1px solid var(--border);cursor:pointer;border-radius:8px;align-items:center;gap:9px;margin-bottom:6px;padding:8px 10px;font-size:.88rem;display:flex}.quiz-opt:hover{border-color:var(--accent)}.quiz-opt.selected{border-color:var(--accent);background:var(--accent-soft)}.quiz-opt.correct{border-color:var(--success);background:var(--success-soft)}.quiz-opt.incorrect{border-color:var(--danger);background:var(--danger-soft)}.quiz-opt input{accent-color:var(--accent)}.quiz-actions{align-items:center;gap:12px;margin-top:6px;display:flex}.quiz-actions button{background:var(--accent);color:#fff;cursor:pointer;border:none;border-radius:8px;padding:9px 18px;font-size:.85rem;font-weight:700}.quiz-result{font-size:.85rem;font-weight:600}.quiz-result.pass{color:var(--success)}.quiz-result.fail{color:var(--danger)}.footer-note{text-align:center;color:var(--text-dim);padding:30px 0 10px;font-size:.75rem}.overlay{display:none}@media (width<=880px){.sidebar{z-index:20;transition:transform 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