#qb *{box-sizing:border-box;font-family:var(--font)}#qb button:focus,#qb input:focus,#qb a:focus{outline:2px solid var(--blue);outline-offset:2px}#qb a{color:inherit;text-decoration:none}.qb-subheader{background:var(--bg-card);border-bottom:var(--border);padding:0 24px}.qb-subheader__inner{max-width:1280px;margin:0 auto;display:flex;align-items:center;height:48px;gap:12px}.qb-subheader__title{font-size:13px;font-weight:700;color:var(--accent)}.qb-subheader__badge{font-size:11px;background:var(--success-light);color:var(--green);padding:3px 10px;border-radius:20px;font-weight:700}.qb-subheader__spacer{flex:1}.qb-subheader__mob-menu{display:none;background:none;border:var(--border);border-radius:6px;padding:5px 10px;font-size:12px;cursor:pointer;color:var(--text-secondary);font-family:var(--font)}.qb-auth-bar{display:flex;align-items:center;gap:10px}#qb-layout{max-width:1280px;margin:0 auto;padding:20px 24px;display:grid;grid-template-columns:260px 1fr;gap:20px;align-items:start}#qb-sidebar{background:var(--bg-card);border:var(--border);border-radius:10px;overflow:hidden;position:sticky;top:72px}.qb-sidebar__header{padding:14px 16px;border-bottom:var(--border);background:var(--gray-50)}.qb-sidebar__heading{font-size:11px;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:.6px;margin:0}#qb-subject-tree{padding:8px 0;max-height:calc(100vh - 160px);overflow-y:auto}.qb-subject-btn{width:100%;display:flex;align-items:center;gap:10px;padding:9px 16px;background:var(--bg-card);border:none;border-left:3px solid transparent;cursor:pointer;text-align:left;font-family:var(--font);transition:background .15s}.qb-subject-btn:hover{background:var(--bg-hover)}.qb-subject-btn--active{background:var(--accent-light);border-left-color:var(--accent)}.qb-subject-btn__name{font-size:12px;font-weight:700;color:var(--text-secondary);display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.qb-subject-btn--active .qb-subject-btn__name{color:var(--accent)}.qb-subject-btn__meta{font-size:10px;color:var(--text-muted)}.qb-chapter-btn{width:100%;display:flex;align-items:center;gap:8px;padding:7px 16px 7px 28px;background:var(--bg-card);border:none;border-left:3px solid transparent;cursor:pointer;text-align:left;font-family:var(--font);transition:background .15s}.qb-chapter-btn:hover{background:var(--bg-hover)}.qb-chapter-btn--active{background:var(--blue-mid);border-left-color:var(--accent)}.qb-chapter-btn__name{font-size:11px;color:var(--text-secondary);font-weight:400;display:block;line-height:1.4}.qb-chapter-btn--active .qb-chapter-btn__name{color:var(--accent);font-weight:600}.qb-chapter-btn__meta{font-size:10px;color:var(--text-muted)}.qb-dot{width:6px;height:6px;border-radius:50%;flex-shrink:0}.qb-dot--active{background:var(--accent)}.qb-dot--empty{background:var(--gray-200)}#qb-breadcrumb{display:flex;align-items:center;gap:6px;margin-bottom:16px;font-size:12px;color:var(--text-secondary)}#qb-breadcrumb a{color:var(--accent)}.qb-panel{background:var(--bg-card);border:var(--border);border-radius:10px;overflow:hidden}.qb-panel__header{padding:16px 20px;border-bottom:var(--border)}.qb-type-toggle{display:flex;background:var(--gray-100);border-radius:7px;padding:3px;gap:2px}.qb-type-btn{padding:5px 14px;border-radius:5px;font-size:12px;font-weight:600;border:none;cursor:pointer;background:transparent;color:var(--text-muted);font-family:var(--font);transition:background .15s,color .15s}.qb-type-btn--active{background:var(--bg-card);color:var(--text);box-shadow:0 1px 3px #0000001a}.qb-diff-bar{display:flex;flex-wrap:wrap;gap:6px;padding:10px 20px;border-bottom:var(--border);background:var(--gray-50)}.qb-diff-chip{font-size:11px;font-weight:700;padding:5px 12px;border-radius:20px;cursor:pointer;border:1px solid var(--border-color);background:var(--bg-card);color:var(--text-muted);font-family:var(--font);transition:background .15s}.qb-q-card{background:var(--bg-card);border-top:var(--border);padding:16px 20px 0}.qb-q-head{display:flex;align-items:flex-start;gap:12px;margin-bottom:10px}.qb-q-num{font-size:11px;font-weight:700;color:var(--blue);background:var(--blue-light);padding:3px 8px;border-radius:4px;white-space:nowrap;flex-shrink:0}.qb-q-num--mains{color:var(--purple);background:#ede9fe}.qb-q-text{font-size:14px;font-weight:500;color:var(--text);margin:0;line-height:1.8;white-space:pre-wrap;font-family:var(--font)}.qb-q-text:first-line{font-weight:700}.qb-option{display:flex;align-items:center;gap:10px;border:1px solid var(--border-color);border-radius:6px;padding:9px 12px;margin-bottom:6px;background:var(--bg-card);cursor:pointer;transition:background .15s}.qb-option:hover{background:var(--bg-hover)}.qb-option--answered{cursor:default}.qb-option--answered:hover{background:inherit}.qb-option--selected{background:var(--accent-light, #eff6ff);border-color:var(--accent, #2563eb)}.qb-option--selected .qb-option__letter{background:var(--accent, #2563eb);color:#fff}.qb-option--correct{background:var(--green-light);border-color:#86efac}.qb-option--wrong{background:var(--red-light);border-color:#fca5a5}.qb-option__letter{width:22px;height:22px;border-radius:50%;background:var(--gray-200);color:var(--text-muted);font-size:10px;font-weight:700;display:flex;align-items:center;justify-content:center;flex-shrink:0}.qb-option--correct .qb-option__letter{background:#16a34a;color:#fff}.qb-option--wrong .qb-option__letter{background:#dc2626;color:#fff}.qb-option__text{font-size:13px;font-weight:400;color:var(--text);flex:1;line-height:1.6;font-family:var(--font)}.qb-option--correct .qb-option__text{color:var(--green)}.qb-option--wrong .qb-option__text{color:var(--red)}.qb-locked-content{position:relative}.qb-locked-blur{mask-image:linear-gradient(to bottom,black 30%,transparent 90%);-webkit-mask-image:linear-gradient(to bottom,black 30%,transparent 90%)}.qb-lock-overlay{text-align:center;padding:12px;font-size:13px;font-weight:600;color:var(--text-secondary)}.qb-lock-overlay span{font-size:16px}.qb-lock-overlay a{color:var(--accent);text-decoration:none;font-weight:700}.qb-lock-overlay a:hover{text-decoration:underline}.qb-mains-action{display:inline-flex;align-items:center;gap:5px;padding:8px 14px;background:#f0f4ff;color:#1a2f5e;border:1px solid #c7d2fe;border-radius:7px;font-size:12px;font-weight:600;cursor:pointer;font-family:var(--font);transition:all .15s}.qb-mains-action:hover{background:#dbeafe;border-color:#93c5fd}.qb-mains-action--upload{background:#f0fdf4;color:#166534;border-color:#bbf7d0}.qb-mains-action--upload:hover{background:#dcfce7;border-color:#86efac}.qb-mains-action--write{background:#fef3c7;color:#92400e;border-color:#fde68a}.qb-mains-action--write:hover{background:#fde68a;border-color:#f59e0b}.qb-explanation--locked{position:relative}.qb-explanation--locked .qb-explanation__text{mask-image:linear-gradient(to bottom,black 40%,transparent 100%);-webkit-mask-image:linear-gradient(to bottom,black 40%,transparent 100%)}.qb-explanation{background:var(--gray-50);border:var(--border);border-radius:6px;padding:12px;margin-top:4px;margin-bottom:8px}.qb-explanation__label{font-size:11px;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:.5px;margin:0 0 6px}.qb-explanation__text{font-size:12px;color:var(--text-secondary);margin:0;line-height:1.7;white-space:pre-wrap}.qb-reveal-btn{background:var(--bg-card);border:1px solid #ddd6fe;color:var(--purple);font-size:12px;font-weight:600;padding:8px 16px;border-radius:6px;cursor:pointer;font-family:var(--font)}.qb-reveal-btn:hover{background:var(--bg-hover)}.qb-diff-tag{font-size:10px;font-weight:700;padding:2px 8px;border-radius:3px;display:inline-block}.qb-wall{background:var(--bg-card);border:var(--border);border-radius:10px;padding:64px 32px;text-align:center}.qb-wall__icon{font-size:36px;margin-bottom:12px}.qb-wall__title{font-size:18px;font-weight:700;color:var(--text);margin:0 0 8px}.qb-wall__desc{font-size:13px;color:var(--text-secondary);margin:0 0 6px}.qb-wall__cta{display:inline-block;background:var(--accent);color:var(--accent-text);font-size:13px;font-weight:700;padding:10px 24px;border:none;border-radius:7px;cursor:pointer;text-decoration:none;font-family:var(--font)}.qb-wall__cta:hover{background:var(--accent-hover)}#qb-page-loading{display:none;text-align:center;padding:16px 0;color:var(--text-muted);font-size:12px}.qb-empty{padding:64px 32px;text-align:center;background:var(--bg-card);border:var(--border);border-radius:10px}.qb-home{background:var(--bg-card);border:var(--border);border-radius:10px;padding:64px 32px;text-align:center}.qb-home__icon{width:48px;height:48px;background:var(--accent-light);border-radius:12px;display:flex;align-items:center;justify-content:center;margin:0 auto 16px}.qb-home__title{font-size:16px;font-weight:700;color:var(--text);margin:0 0 8px}.qb-home__desc{font-size:13px;color:var(--text-secondary);margin:0 0 24px}.qb-quick-subjects{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}.qb-quick-btn{background:var(--bg-card);border:var(--border);border-radius:6px;padding:7px 14px;font-size:12px;font-weight:600;color:var(--text-secondary);cursor:pointer;font-family:var(--font);transition:background .15s}.qb-quick-btn:hover{background:var(--bg-hover)}#qb-page-footer{text-align:center;padding:20px;border-top:var(--border)}.qb-seo-intro{background:var(--bg-card);border-bottom:var(--border);padding:18px 24px}.qb-seo-intro__inner{max-width:1280px;margin:0 auto}.qb-seo-intro h1{font-size:28px;line-height:1.2;font-weight:800;color:var(--text);margin:0 0 8px}.qb-seo-intro p{max-width:840px;font-size:14px;line-height:1.6;color:var(--text-secondary);margin:0 0 8px}.qb-seo-intro ul{display:flex;flex-wrap:wrap;gap:8px;list-style:none;padding:0;margin:12px 0 0}.qb-seo-intro li{font-size:12px;font-weight:700;color:var(--accent);background:var(--blue-light);border:1px solid var(--border-color);border-radius:6px;padding:6px 10px}@media(max-width:768px){#qb-layout{grid-template-columns:1fr!important}#qb-sidebar{display:none}#qb-sidebar.mob-open{display:block;position:fixed;inset:0;z-index:200;overflow-y:auto;background:var(--bg-card)}.qb-subheader__mob-menu{display:block}.qb-seo-intro h1{font-size:22px}.qb-seo-intro p{font-size:13px}.qb-q-card{padding:12px 14px 0}}.qb-hw-answer{margin-top:12px;border-radius:10px;overflow:hidden;border:1px solid #e8e0d8}.qb-hw-answer__header{padding:8px 14px;background:#f8f5f0;border-bottom:1px solid #e8e0d8}.qb-hw-answer__label{font-size:11px;font-weight:700;color:var(--purple, #7c3aed);text-transform:uppercase;letter-spacing:.5px}.qb-hw-answer__page{background:#fffef5;padding:16px 16px 16px 32px;position:relative;background-image:repeating-linear-gradient(transparent,transparent 27px,#e8e0d8 27px,#e8e0d8 28px);line-height:28px}.qb-hw-answer__page:before{content:"";position:absolute;left:24px;top:0;bottom:0;width:1px;background:#f0c0c0;opacity:.6}.qb-hw-answer__text{font-family:Kalam,cursive;font-size:13px;color:#1e293b;line-height:28px}.qb-hw-answer__text p{margin:0;padding:0}.qb-hw-answer__hl{background:#fef08a;padding:1px 4px;border-radius:2px;font-weight:700;color:#1e293b}.qb-hw-answer__text strong{color:#1e40af;text-decoration:underline;text-decoration-color:#93c5fd;text-underline-offset:2px}.qb-hw-answer--locked .qb-hw-answer__page{mask-image:linear-gradient(to bottom,black 40%,transparent 100%);-webkit-mask-image:linear-gradient(to bottom,black 40%,transparent 100%)}