:root{--bg:#f7f8fb;--card:#fff;--text:#172033;--muted:#697386;--brand:#2563eb;--brand2:#7c3aed;--ok:#16a34a;--warn:#f59e0b;--bad:#ef4444;--line:#e5e7eb;--shadow:0 18px 45px rgba(15,23,42,.08);--radius:22px}*{box-sizing:border-box}body{margin:0;background:linear-gradient(180deg,#eef4ff 0%,#f7f8fb 330px);color:var(--text);font-family:Inter,system-ui,-apple-system,Segoe UI,Arial,sans-serif}a{text-decoration:none;color:inherit}.nav{position:sticky;top:0;z-index:10;background:rgba(255,255,255,.86);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}.nav-inner{max-width:1180px;margin:auto;padding:14px 18px;display:flex;align-items:center;gap:18px}.logo{font-weight:900;letter-spacing:-.03em;font-size:20px}.logo span{color:var(--brand)}.links{display:flex;gap:8px;flex:1;flex-wrap:wrap}.links a{font-size:14px;color:var(--muted);padding:9px 12px;border-radius:999px}.links a.active,.links a:hover{background:#eaf1ff;color:var(--brand)}.auth-slot{display:flex;align-items:center;gap:8px}.btn{border:0;border-radius:14px;padding:11px 16px;background:linear-gradient(135deg,var(--brand),var(--brand2));color:white;font-weight:800;cursor:pointer;box-shadow:0 10px 20px rgba(37,99,235,.18)}.btn.secondary{background:#fff;color:var(--brand);border:1px solid #cfe0ff;box-shadow:none}.btn.ghost{background:#f1f5f9;color:#334155;box-shadow:none}.container{max-width:1180px;margin:auto;padding:28px 18px 60px}.hero{display:grid;grid-template-columns:1.15fr .85fr;gap:28px;align-items:center;padding:34px 0}.pill{display:inline-flex;align-items:center;gap:8px;background:#fff;border:1px solid var(--line);border-radius:999px;padding:8px 12px;color:var(--brand);font-weight:800;font-size:13px}.hero h1{font-size:56px;line-height:.98;margin:16px 0 14px;letter-spacing:-.06em}.hero p,.lead{font-size:18px;line-height:1.65;color:var(--muted);max-width:760px}.grid{display:grid;gap:16px}.grid.cols3{grid-template-columns:repeat(3,1fr)}.grid.cols2{grid-template-columns:repeat(2,1fr)}.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}.card h3{margin:0 0 10px;font-size:20px}.muted{color:var(--muted)}.section-title{font-size:34px;letter-spacing:-.04em;margin:30px 0 12px}.module{margin:22px 0;background:#fff;border:1px solid var(--line);border-radius:26px;overflow:hidden;box-shadow:var(--shadow)}.module-head{padding:22px;background:linear-gradient(135deg,#172033,#27395c);color:white;display:flex;justify-content:space-between;gap:14px;align-items:flex-start}.module-head h2{margin:0;font-size:26px}.module-meta{font-size:13px;opacity:.8}.topic{display:grid;grid-template-columns:90px 1fr 160px;gap:16px;padding:18px 22px;border-top:1px solid var(--line);align-items:start}.topic:hover{background:#f8fbff}.topic-num{font-weight:900;color:var(--brand)}.topic h3{margin:0 0 6px;font-size:18px}.topic ul{margin:8px 0 0 18px;color:var(--muted);line-height:1.55}.tag{display:inline-flex;border-radius:999px;background:#eef2ff;color:#4338ca;font-weight:800;font-size:12px;padding:7px 10px}.toolbar{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}.tab{border:1px solid var(--line);background:#fff;border-radius:999px;padding:10px 14px;cursor:pointer;color:#475569;font-weight:800}.tab.active{background:#172033;color:#fff}.task,.question{background:#fff;border:1px solid var(--line);border-radius:20px;padding:18px;margin:12px 0}.task-top{display:flex;gap:8px;justify-content:space-between;align-items:center}.rubric{width:100%;border-collapse:separate;border-spacing:0;background:#fff;border:1px solid var(--line);border-radius:18px;overflow:hidden;box-shadow:var(--shadow)}.rubric th,.rubric td{padding:14px;border-bottom:1px solid 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#bbf7d0;color:#166534;border-radius:16px}.footer{text-align:center;color:var(--muted);padding:28px}@media(max-width:800px){.hero{grid-template-columns:1fr}.hero h1{font-size:40px}.grid.cols3,.grid.cols2{grid-template-columns:1fr}.topic{grid-template-columns:1fr}.nav-inner{align-items:flex-start;flex-direction:column}.links{width:100%;overflow:auto;flex-wrap:nowrap}.auth-slot{width:100%;justify-content:space-between}}

/* ===== THEORY CODE BLOCKS ===== */
.theory-code{background:#1e293b;border-radius:12px;padding:18px 20px;margin:12px 0 18px;overflow-x:auto}
.theory-code pre{font-family:'Courier New',Courier,monospace;font-size:14px;color:#e2e8f0;line-height:1.8;white-space:pre;margin:0}

/* ===== LESSON MODAL ===== */
.lesson-modal{position:fixed;inset:0;background:rgba(15,23,42,.72);display:none;align-items:flex-start;justify-content:center;padding:20px;z-index:999;overflow-y:auto}
.lesson-modal.open{display:flex}
.lesson-box{background:#fff;border-radius:24px;max-width:780px;width:100%;margin:auto;overflow:hidden;box-shadow:0 40px 100px rgba(0,0,0,.3)}
.lesson-header{padding:20px 28px;background:linear-gradient(135deg,#172033,#2563eb);color:#fff;display:flex;justify-content:space-between;align-items:center}
.lesson-header h2{margin:0;font-size:19px;font-weight:800}
.lesson-close{width:34px;height:34px;border-radius:50%;background:rgba(255,255,255,.2);border:none;color:#fff;font-size:19px;cursor:pointer;display:grid;place-items:center;line-height:1}
.lesson-body{padding:28px;max-height:78vh;overflow-y:auto}
.lesson-body h3{font-size:17px;font-weight:800;color:var(--brand);margin:22px 0 10px}
.lesson-body h3:first-child{margin-top:0}
.lesson-body p{margin-bottom:12px;line-height:1.7}
.lesson-body b{color:var(--text)}
.goal-notice{background:#eff6ff;border:1px solid #bfdbfe;border-radius:12px;padding:12px 16px;margin-bottom:20px;color:#1d4ed8;font-size:14px;line-height:1.6}

/* ===== EXERCISES ===== */
.topic-clickable:hover{background:#f8fbff;cursor:pointer}
.exercise-card{border-left:4px solid transparent;transition:border-color .3s}