/* Giao diện bài tập + hộp lý thuyết dùng chung cho Bài 1, 2, 3 (nạp sau lesson.css) */
.tabs{display:flex;gap:8px;justify-content:center;margin:8px 0}
.tabs button{font:inherit;font-weight:700;padding:8px 20px;border-radius:999px;border:1.5px solid var(--navy);background:transparent;color:var(--navy);cursor:pointer}
.tabs button.on{background:var(--navy);color:var(--bg)}
.panel{display:none}.panel.on{display:block}
.box{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:12px 14px}
.chips{display:flex;flex-wrap:wrap;gap:6px;margin:8px 0}
.chips button{font:inherit;font-size:.8rem;padding:3px 10px;border-radius:999px;border:1.5px solid var(--line);background:transparent;color:var(--ink);cursor:pointer}
.chips button.on{background:var(--navy);color:var(--bg);border-color:var(--navy)}
.detail h2{margin:0 0 6px;font-size:1.25rem;color:var(--navy)}
.detail .crumb{font-size:.82rem;color:var(--muted);margin-bottom:8px;display:flex;flex-wrap:wrap;gap:4px;align-items:center}
.detail .crumb a{color:var(--navy);cursor:pointer;text-decoration:underline}
.detail .defTxt{white-space:pre-line;font-size:1rem;background:color-mix(in srgb,var(--navy) 8%,var(--card));border-radius:12px;padding:10px 14px}
.detail .kids{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px}
.detail .kids a{font-size:.8rem;border:1.5px solid var(--c);border-radius:999px;padding:2px 10px;cursor:pointer;color:var(--ink);background:color-mix(in srgb,var(--c) 10%,var(--card))}
.sub{font-size:.8rem;color:var(--muted);margin:10px 0 4px;font-weight:700;text-transform:uppercase;letter-spacing:.03em}
.terms{margin-top:2px}
/* bài tập */
.setup label{display:block;margin:6px 0;font-size:.95rem}
.setup select{font:inherit;padding:5px 8px;border-radius:8px;border:1.5px solid var(--line);background:var(--card);color:var(--ink);max-width:100%}
.setup .tools{display:flex;gap:12px;margin:2px 0 4px}
.setup .tools button{font:inherit;font-size:.78rem;border:0;background:none;color:var(--navy);text-decoration:underline;cursor:pointer;padding:0}
.types{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:4px 12px;margin:6px 0}
.big{font:inherit;font-weight:700;padding:10px 24px;border-radius:12px;border:0;background:var(--navy);color:var(--bg);cursor:pointer;font-size:1rem;margin-top:10px}
.qhead{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;font-size:.88rem;color:var(--muted);margin-bottom:6px}
.qhead .lnk{font:inherit;font-size:.8rem;border:1px solid var(--line);background:transparent;color:var(--muted);border-radius:8px;padding:0 8px;margin-left:10px;cursor:pointer}
.qtype{background:color-mix(in srgb,var(--navy) 12%,var(--card));color:var(--navy);border-radius:999px;padding:1px 10px;font-weight:700;font-size:.78rem}
.qp{font-size:1.08rem;margin:6px 0 10px}
.qp blockquote{margin:8px 0;padding:8px 12px;border-left:4px solid var(--navy);background:color-mix(in srgb,var(--navy) 8%,var(--card));border-radius:8px;white-space:pre-line;font-size:.98rem}
.opts2{display:grid;gap:8px}
.opts2 button,.tile{font:inherit;text-align:left;padding:10px 12px;border-radius:10px;border:1.5px solid var(--line);background:var(--card);color:var(--ink);cursor:pointer;font-size:.95rem}
.opts2 button:hover:not(:disabled),.tile:hover:not(.lock){border-color:var(--navy)}
.opts2 button.right,.tile.right{background:color-mix(in srgb,var(--sohuu) 22%,var(--card));border-color:var(--sohuu)}
.opts2 button.wrong,.tile.wrong{background:color-mix(in srgb,var(--tam) 22%,var(--card));border-color:var(--tam)}
.opts2.two{grid-template-columns:1fr 1fr}
.tile.sel{border-color:var(--navy);box-shadow:0 0 0 2px var(--navy)}
.tile.lock{cursor:default}
.mcols{display:grid;grid-template-columns:1fr 1.6fr;gap:12px}
@media (max-width:700px){.mcols{grid-template-columns:1fr}}
.mcols .col{display:grid;gap:8px;align-content:start}
.ansrow{display:flex;gap:8px}
.ansrow input{flex:1;font:inherit;padding:9px 10px;border-radius:10px;border:1.5px solid var(--line);background:var(--card);color:var(--ink)}
.btn2{font:inherit;font-weight:700;padding:8px 16px;border-radius:10px;border:1.5px solid var(--navy);background:transparent;color:var(--navy);cursor:pointer}
.btn2.pri{background:var(--navy);color:var(--bg)}
.fb{margin-top:10px;padding:10px 12px;border-radius:10px;font-size:.95rem;display:none}
.fb.ok{display:block;background:color-mix(in srgb,var(--sohuu) 16%,var(--card))}
.fb.no{display:block;background:color-mix(in srgb,var(--tam) 14%,var(--card))}
.fb .row{display:flex;gap:8px;margin-top:8px;flex-wrap:wrap}
.prog{height:8px;background:var(--line);border-radius:6px;overflow:hidden;margin-bottom:10px}
.prog div{height:100%;background:var(--sohuu);width:0}
.res h2{margin:0 0 6px;color:var(--navy)}
.res .score{font-size:2rem;font-weight:800;color:var(--navy)}
.res table{border-collapse:collapse;width:100%;font-size:.9rem;margin:8px 0}
.res td,.res th{border-bottom:1px solid var(--line);padding:4px 8px;text-align:left}
.wrongList button{font:inherit;font-size:.85rem;margin:2px 4px 2px 0;border:1px solid var(--line);background:transparent;color:var(--navy);border-radius:8px;padding:2px 8px;cursor:pointer}
dialog.theory{border:1px solid var(--line);border-radius:18px;padding:0;max-width:720px;width:calc(100% - 28px);background:var(--card);color:var(--ink);box-shadow:0 20px 60px #0005}
dialog.theory::backdrop{background:rgba(20,20,30,.55)}
dialog.theory .in{padding:18px 20px;position:relative}
dialog.theory .x{position:absolute;top:10px;right:10px;border:1px solid var(--line);background:none;border-radius:10px;width:32px;height:32px;cursor:pointer;color:var(--muted);font-size:14px}
/* Dạng "tự viết rồi tự chấm" và "điền từ thiếu" (bài tập ngôn ngữ, Bài 3) */
.selfw{width:100%;font:inherit;padding:9px 10px;border-radius:10px;border:1.5px solid var(--line);background:var(--card);color:var(--ink);resize:vertical}
.selfref{margin-top:10px;padding:10px 12px;border-radius:10px;border-left:4px solid var(--sohuu);background:color-mix(in srgb,var(--sohuu) 10%,var(--card))}
.selfgrade{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-top:10px}
.qp u.blank{text-decoration:none;display:inline-block;min-width:3em;border-bottom:2px solid var(--navy);color:var(--navy);text-align:center}