.box-nen{background:var(--nen);border:0}.note-do{border-color:var(--do);background:var(--do-nhat)}.auth-box{max-width:440px;margin:32px auto}.player-wrap{position:relative;background:#000;border-radius:var(--r);overflow:hidden;aspect-ratio:16 / 9}.player-wrap video,.player-wrap iframe{position:absolute;top:0;right:0;bottom:0;left:0;width:100%;height:100%;border:0}.wm{position:absolute;z-index:3;pointer-events:none;color:#ffffff61;font-weight:600;font-size:clamp(11px,1.6vw,15px);text-shadow:0 0 2px rgba(0,0,0,.5);transition:top 1s,left 1s;white-space:nowrap}.player-msg{position:absolute;top:0;right:0;bottom:0;left:0;z-index:4;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;text-align:center;padding:20px;color:#fff;background:#0d192deb}.player-msg h3{color:#fff}.player-msg[hidden]{display:none}.learn{display:grid;gap:20px;padding:16px 0 40px}.hoc-muc-luc{border:1px solid var(--vien);border-radius:var(--r-lon);background:#fff;overflow:hidden}.hoc-muc-luc summary{display:flex;align-items:center;gap:8px;padding:12px 14px;cursor:pointer;font-weight:600;background:var(--nen);list-style:none}.hoc-muc-luc summary::-webkit-details-marker{display:none}.hoc-muc-luc-t{flex:1}.hoc-muc-luc-bai{font-weight:400;color:var(--chu-phu);font-size:.85rem;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:45%}.hoc-muc-luc-mui{color:var(--chu-phu);transition:transform .2s}.hoc-muc-luc[open] .hoc-muc-luc-mui{transform:rotate(180deg)}.hoc-muc-luc[open] summary{border-bottom:1px solid var(--vien)}.hoc-muc-luc .toc{border:0;border-radius:0;max-height:62vh;overflow:auto}@media (max-width: 999px){.hoc-toc{display:none}}@media (min-width: 1000px){.learn{grid-template-columns:320px minmax(0,1fr)}.hoc-muc-luc{display:none}.hoc-toc{position:sticky;top:80px;max-height:calc(100vh - 120px);overflow:auto}}.pbar{height:8px;background:var(--vien);border-radius:999px;overflow:hidden}.pbar i{display:block;height:100%;background:var(--xanh-ok)}.qr-box{text-align:center}.qr-box img{width:280px;max-width:100%;border-radius:12px;border:1px solid var(--vien);background:#fff}.qr-fallback{width:280px;max-width:100%;aspect-ratio:1;margin:0 auto;border:2px dashed var(--vien);border-radius:12px;display:flex;align-items:center;justify-content:center;padding:16px;color:var(--chu-phu);font-size:.9rem}.copy-btn{border:1px solid var(--vien);background:#fff;border-radius:8px;padding:2px 8px;cursor:pointer;font:inherit;font-size:.8rem;margin-left:6px}.admin-side{min-width:0}.admin-side{background:var(--navy-dam);color:#fff;padding:16px}.admin-side a{display:block;color:#d7e2f3;text-decoration:none;padding:8px 10px;border-radius:8px;font-weight:600;font-size:.95rem}.admin-side a[aria-current],.admin-side a:hover{background:#ffffff1f;color:#fff}.admin-side .brand{font-weight:800;color:#fff;margin-bottom:12px;display:block}@media (max-width: 899px){.admin-side nav{display:flex;overflow-x:auto;gap:4px}.admin-side a{white-space:nowrap}}.admin-main{padding:20px 16px 60px;background:var(--nen);min-width:0}.admin-main h1{font-size:1.5rem}.admin-main .form{grid-template-columns:minmax(0,1fr)}.admin-main .form>*,.admin-main .grid>*{min-width:0}.admin-main input:not([type=checkbox]):not([type=radio]),.admin-main select,.admin-main textarea{max-width:100%;box-sizing:border-box}.kpis{display:grid;gap:12px;grid-template-columns:repeat(auto-fill,minmax(170px,1fr));margin-bottom:20px}.kpi{background:#fff;border-radius:var(--r);padding:14px;border:1px solid var(--vien)}.kpi b{display:block;font-size:1.5rem;color:var(--navy)}.toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:end;margin-bottom:14px}.toolbar .field{min-width:160px}.fs-btn{position:absolute;z-index:5;top:8px;right:8px;width:40px;height:40px;border:0;border-radius:8px;background:#00000073;color:#fff;font-size:20px;cursor:pointer}.player-wrap:fullscreen{border-radius:0;aspect-ratio:auto}.ve-o-link{display:flex;gap:12px;align-items:center;text-decoration:none;color:var(--navy-dam)}.ve-o-f{display:flex;justify-content:space-between;align-items:center;gap:8px;flex-wrap:wrap}.hoc-chuong{list-style:none;margin:0;padding:0;display:grid;gap:12px}.hoc-chuong li{background:#fff;border:1px solid var(--vien);border-radius:14px;padding:16px}.hoc-chuong li.khoa{background:var(--giay)}.hoc-chuong-h{display:flex;justify-content:space-between;gap:10px;align-items:center;margin-bottom:6px}.hoc-bai{margin:8px 0 0;padding-left:1.3em}.kt-cau{border:1px solid var(--vien);border-radius:12px;padding:14px 16px;margin:0;background:#fff}.kt-cau legend{padding:0 6px;font-size:.85rem;color:var(--muted, #5b6b7f)}.kt-so{font-weight:800;color:var(--cam-dam)}.kt-de{margin:4px 0 10px;font-weight:600;color:var(--navy-dam)}.kt-opts{display:grid;gap:8px}.kt-opt{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border:1px solid var(--vien);border-radius:10px;cursor:pointer}.kt-opt:hover{border-color:var(--cam);background:var(--cam-nhat)}.kt-opt input{margin-top:3px}.kt-dien{width:100%;max-width:420px;min-height:44px;padding:8px 12px;border:1px solid var(--vien);border-radius:10px;font:inherit}.kt-diem{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap;padding:14px 16px;border-radius:12px}.kt-diem b{font-size:2rem}.kt-diem.dat{background:#e7f6ec;color:#14532d}.kt-diem.chua{background:var(--do-nhat);color:#7f1d1d}.kt-ds{list-style:none;margin:0;padding:0;display:grid;gap:10px}.kt-kq{border-left:4px solid var(--vien);border-radius:8px;background:#fff;padding:10px 14px;border-top:1px solid var(--vien);border-right:1px solid var(--vien);border-bottom:1px solid var(--vien)}.kt-kq.dung{border-left-color:#1f9d55}.kt-kq.sai{border-left-color:var(--do)}.kt-giai-thich{color:var(--navy-dam);background:var(--navy-nhat);padding:6px 10px;border-radius:8px;margin-top:6px}