:root{--bg:#f5f7fb;--panel:#fff;--text:#172033;--muted:#8d9ab0;--line:#26364f;--line2:#e4e9f1;--accent:#4e83ff;--accent2:#172b4a;--sidebar:#0b1627;--sidebar2:#101e33}
*{box-sizing:border-box}html{scroll-behavior:auto}body{margin:0;background:var(--bg);color:var(--text);font:16px/1.65 system-ui,-apple-system,"Segoe UI",Arial,sans-serif}a{color:var(--accent)}
.app{display:grid;grid-template-columns:315px minmax(0,1fr);min-height:100vh}.sidebar{position:fixed;left:0;top:0;bottom:0;width:315px;overflow-y:auto;overflow-x:hidden;background:linear-gradient(180deg,var(--sidebar),#091322);color:#dbe5f4;padding:16px 12px 30px;scrollbar-gutter:stable;z-index:20}.main{grid-column:2;min-width:0}.brand{font-weight:850;font-size:18px;margin:0 8px 2px}.sub{font-size:12px;color:#91a1b8;margin:0 8px 15px}.search{position:sticky;top:0;background:linear-gradient(180deg,var(--sidebar) 75%,transparent);padding:3px 0 13px;z-index:3}.search input{width:100%;padding:10px 12px;border-radius:10px;border:1px solid #30425d;background:#17263c;color:#fff;outline:none}.search input::placeholder{color:#7f91aa}
.nav-group{margin:5px 0;border-radius:10px;overflow:hidden}.nav-group summary{list-style:none;cursor:pointer;display:flex;align-items:center;gap:9px;padding:9px 9px;color:#dbe5f4;font-size:12px;font-weight:800;text-transform:uppercase;letter-spacing:.06em;border-radius:9px;background:rgba(255,255,255,.025)}.nav-group summary::-webkit-details-marker{display:none}.nav-group summary:hover{background:#15253c}.group-num{display:inline-grid;place-items:center;min-width:25px;height:22px;border-radius:6px;background:#182b47;color:#83a4d5;font-size:11px}.chev{margin-left:auto;color:#7990b1;font-size:20px;line-height:1;transform:rotate(0deg);transition:.15s}.nav-group[open]>summary .chev{transform:rotate(90deg);color:#a9c5f4}.nav{padding:3px 0 6px}.nav a,.test-sub a{display:flex;align-items:flex-start;gap:7px;color:#cbd7e8;text-decoration:none;padding:6px 8px;border-radius:7px;font-size:12px;line-height:1.32}.nav a:hover,.nav a.active,.test-sub a:hover,.test-sub a.active{background:#172940;color:#fff}.nav a .n,.test-sub a .n{color:#7186a7;min-width:31px;font-variant-numeric:tabular-nums}.nav a.active .n,.test-sub a.active .n{color:#9fc0ff}.test-sub{border-top:1px solid rgba(255,255,255,.06);padding:7px 0}.test-subtitle{font-size:10px;text-transform:uppercase;color:#8295b1;letter-spacing:.07em;padding:4px 8px 3px}.test-group summary{background:#142744}.no-results{display:none;padding:10px;color:#7f91aa;font-size:12px}
.content{max-width:1040px;margin:0 auto;padding:34px 30px 70px}.topbar{position:sticky;top:0;z-index:10;background:rgba(245,247,251,.95);backdrop-filter:blur(8px);border-bottom:1px solid var(--line2);padding:11px 28px;display:flex;justify-content:space-between;align-items:center}.crumb{color:#748198;font-size:13px}.homebtn{background:#fff;border:1px solid var(--line2);border-radius:9px;padding:7px 11px;text-decoration:none;color:#243149;font-size:13px}.hero{background:linear-gradient(135deg,#111d34,#21428e);color:#fff;border-radius:17px;padding:27px 29px;margin-bottom:22px;box-shadow:0 10px 30px rgba(16,24,40,.08)}.hero h1{font-size:31px;line-height:1.2;margin:0 0 9px}.hero p{margin:0;color:#dbe8ff}.article{background:var(--panel);border:1px solid var(--line2);border-radius:16px;padding:30px;box-shadow:0 8px 30px rgba(16,24,40,.06)}.article h2,.article h3,.article h4{line-height:1.3;color:#101828}.article img{max-width:100%;height:auto;border-radius:10px}.article table{max-width:100%;display:block;overflow:auto;border-collapse:collapse}.article td,.article th{border:1px solid var(--line2);padding:7px}.article pre{overflow:auto;background:#0b1220;color:#e5e7eb;padding:16px;border-radius:10px}.article blockquote{border-left:4px solid var(--accent);padding-left:16px;color:#475467}.pager{display:flex;justify-content:space-between;gap:12px;margin-top:18px}.pager a{background:#fff;border:1px solid var(--line2);border-radius:10px;padding:10px 14px;text-decoration:none;color:var(--text)}.badge{display:inline-block;font-size:12px;padding:4px 8px;border-radius:999px;background:#eef4ff;color:#1d4ed8;margin-bottom:10px}.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}.card{background:#fff;border:1px solid var(--line2);border-radius:14px;padding:18px;text-decoration:none;color:var(--text);box-shadow:0 8px 25px rgba(16,24,40,.05)}.card h3{margin:0 0 7px;font-size:17px}.card p{margin:0;color:#667085;font-size:13px}
@media(max-width:900px){.app{display:block}.sidebar{position:fixed;width:min(88vw,330px);transform:translateX(-105%);transition:.2s}.sidebar.open{transform:none}.main{grid-column:auto}.mobile-nav{display:flex;position:fixed;bottom:0;left:0;right:0;background:#0b1627;z-index:30;padding:8px;gap:8px}.mobile-nav a{flex:1;text-align:center;color:#fff;text-decoration:none;padding:8px;background:#172940;border-radius:8px;font-size:12px}.topbar{padding:10px 14px}.content{padding:20px 14px 76px}.article{padding:20px}.hero{padding:22px}.hero h1{font-size:25px}}
@media(min-width:901px){.mobile-nav{display:none}}

/* V7 navigation: sections only, high contrast */
.nav-group{margin:7px 0;border-radius:10px;overflow:hidden;border:1px solid rgba(45,66,95,.55)}
.nav-group summary{background:#07111f;color:#f2f6fc;border:1px solid #213653;padding:10px 10px;font-size:12px;font-weight:850;letter-spacing:.045em}
.nav-group summary:hover{background:#0b1a2d}
.nav-group[open]>summary{background:#050d18;color:#fff;border-color:#36567e}
.nav-group .group-num{display:none}
.nav{background:#0f1d30;padding:5px 4px 7px}
.nav a,.test-sub a{color:#d7e2f0;padding:7px 8px;font-size:12px;border-radius:7px}
.nav a:hover,.test-sub a:hover{background:#1a2d47;color:#fff}
.nav a.active,.test-sub a.active{background:#29466a;color:#fff;box-shadow:inset 3px 0 0 #6fa0ff}
.nav a .n,.test-sub a .n{display:none}
.test-group summary{background:#07111f!important;border-color:#304b70!important}
.test-sub{background:#0b1728;border-top:1px solid #213653;padding:7px 4px}
.test-subtitle{color:#8eabd0;font-weight:800;padding:5px 8px 3px}
/* Avoid browser auto-scroll surprises while the sidebar is rebuilt */
.sidebar{overscroll-behavior:contain}

/* V8: section-first navigation, no lesson numbering */
.nav-group{margin:8px 0;border:1px solid #28405f;border-radius:11px;overflow:hidden}
.nav-group summary{background:#020916!important;color:#ffffff!important;border:1px solid #405d82!important;min-height:42px;padding:10px 12px;font-size:12px;font-weight:900;letter-spacing:.05em;box-shadow:inset 0 -1px 0 rgba(255,255,255,.04)}
.nav-group summary:hover{background:#071425!important;border-color:#5a78a1!important}
.nav-group[open]>summary{background:#010611!important;border-color:#6383ad!important}
.nav{background:#14263e!important;padding:6px 5px 8px}
.nav a{color:#e6edf7!important;padding:8px 9px!important;font-size:12px!important}
.nav a:hover{background:#213b5e!important}
.nav a.active{background:#355b88!important;color:#fff!important;box-shadow:inset 4px 0 0 #8ab5ff}
.nav a.test-link{margin-top:6px;background:#0b1728!important;border:1px solid #3e5f85;color:#dceaff!important;font-weight:800}
.nav a.test-link:hover{background:#193452!important}
.nav a .test-icon{display:inline-grid;place-items:center;min-width:20px;height:20px;border-radius:5px;background:#284f7d;color:#fff;font-weight:900}
.nav-group summary .chev{color:#b5c9e5!important}
.content{padding-top:26px}


/* V9: stronger separation between section headers and lesson items */
.nav-group summary{background:#020916!important;color:#ffffff!important;border-color:#3f5b7d!important}
.nav-group summary:hover{background:#061225!important;border-color:#6687b1!important}
.nav-group[open]>summary{background:#010611!important;color:#ffffff!important;border-color:#6c8fb9!important}
.nav{background:#1b304b!important;padding:7px 6px 9px!important}
.nav a{background:#203a59!important;color:#f4f7fb!important;padding:9px 10px!important;font-size:12.5px!important;margin:2px 0!important}
.nav a:hover{background:#2b4d72!important;color:#ffffff!important}
.nav a.active{background:#416fa5!important;color:#ffffff!important;box-shadow:inset 4px 0 0 #a9ceff}
.nav a.test-link{background:#102238!important;border-color:#6d91bb!important;color:#ffffff!important}
.nav a.test-link:hover{background:#294b72!important}

/* V10: original course structure + high contrast navigation */
.nav-group{margin:8px 0;border:1px solid #29496f;border-radius:11px;overflow:hidden;background:#0d1d31}
.nav-group summary{background:#030a14!important;color:#fff!important;border:1px solid #52749f!important;min-height:44px;padding:11px 12px;font-size:12px;font-weight:900;letter-spacing:.05em;box-shadow:inset 0 -1px 0 rgba(255,255,255,.06)}
.nav-group summary:hover{background:#071525!important;border-color:#82a9d6!important}
.nav-group[open]>summary{background:#07111f!important;border-color:#83a9d5!important}
.nav{background:#203b5d!important;padding:7px 6px 9px!important}
.nav a{background:#2f5278!important;color:#ffffff!important;padding:9px 10px!important;font-size:12.5px!important;margin:3px 0!important;border:1px solid rgba(255,255,255,.10)}
.nav a:hover{background:#416b98!important;color:#fff!important;border-color:rgba(255,255,255,.2)}
.nav a.active{background:#5b86b5!important;color:#fff!important;box-shadow:inset 4px 0 0 #d9ecff}
.nav a.test-link{background:#10233a!important;border-color:#8ab2df!important;color:#fff!important;font-weight:850}
.nav a.test-link:hover{background:#254b73!important}
.nav a .test-icon{display:inline-grid;place-items:center;min-width:20px;height:20px;border-radius:5px;background:#3d6f9f;color:#fff;font-weight:900}
.nav-group summary .chev{color:#d0e3f7!important}
.nav-final{margin:8px 0 20px;border-top:1px solid #355778;padding-top:8px}
.nav-final a{display:flex;align-items:center;gap:7px;text-decoration:none;color:#fff;background:#10233a;border:1px solid #8ab2df;border-radius:9px;padding:10px;font-size:12.5px;font-weight:850}
.nav-final a:hover{background:#254b73}

/* V13 integrated local resources */
.resource-box{
  margin:28px 0 22px;padding:18px 20px;border:1px solid #b8cce0;border-radius:14px;
  background:#f5f9fd;box-shadow:0 4px 16px rgba(16,33,58,.06)
}
.resource-box h2,.resource-box h3{margin:0 0 10px;color:#10213a}
.resource-box p{margin:7px 0 12px}
.resource-list{display:grid;gap:10px;margin-top:12px}
.resource-link{
  display:flex;gap:12px;align-items:flex-start;padding:12px 14px;border:1px solid #bfd0e1;
  border-radius:10px;background:#fff;color:#10213a!important;text-decoration:none!important
}
.resource-link:hover{background:#eaf3fb;border-color:#7fa7ce}
.resource-icon{font-size:1.35rem;line-height:1.2}
.resource-meta{display:block;color:#60748b;font-size:.9rem;margin-top:3px}
.lesson-video{width:100%;max-height:70vh;border-radius:12px;background:#000;margin:10px 0 4px}
.resource-note{font-size:.92rem;color:#52677e}