:root{--primary: #8e44ad;--primary-dark: #6c3483;--primary-light: rgba(142, 68, 173, .1);--secondary: #3498db;--success: #27ae60;--warning: #e67e22;--danger: #e74c3c;--text: #2c3e50;--text-muted: #666;--border: #e9ecef;--bg: #f4f7f6;--card-bg: #ffffff;--shadow: 0 4px 12px rgba(0, 0, 0, .08)}body{font-family:Inter,sans-serif;background-color:var(--bg);color:var(--text);margin:0;padding:0;transition:background-color .3s,color .3s}body.dark-mode{background-color:#121212!important;color:#e0e0e0!important;--bg: #121212;--card-bg: #1e1e2e;--border: #333;--text: #e0e0e0;--text-muted: #aaa}body.dark-mode .card-premium,body.dark-mode .concept-card,body.dark-mode .section-card{background-color:#1e1e2e!important;border-color:#333!important;color:#e0e0e0!important}body.dark-mode .section-title,body.dark-mode .card-title,body.dark-mode h1,body.dark-mode h2,body.dark-mode h3{color:#c39bd3!important}body.dark-mode table{background:#1e1e2e!important;color:#e0e0e0!important}body.dark-mode th{background:#2c1654!important}body.dark-mode td{border-color:#333!important}body.dark-mode .solution-details summary{color:#c39bd3!important}body.dark-mode .solution-details{background:#1e1e2e!important;border-color:#333!important}body:not(.lang-mode-hi) .lang-hi{display:none!important}body.lang-mode-hi .lang-en{display:none!important}.top-controls{position:absolute;top:20px;right:20px;display:flex;gap:10px;z-index:100}.lang-toggle-btn{padding:8px 12px;border-radius:20px;border:1px solid var(--primary);background:#fff;color:var(--primary);cursor:pointer;font-weight:700;font-family:Inter,sans-serif;transition:background .2s}.lang-toggle-btn:hover{background:var(--primary-light)}body.dark-mode .lang-toggle-btn{background:#1e1e2e;color:#c39bd3;border-color:#c39bd3}.container{max-width:900px;margin:0 auto;padding:20px;position:relative}.breadcrumbs{padding:10px 0 5px;font-size:.9rem;color:var(--text-muted)}.breadcrumbs a{color:var(--primary);text-decoration:none}.breadcrumbs a:hover{text-decoration:underline}.breadcrumbs .separator{margin:0 8px}.page-header{text-align:center;padding:30px 0 20px;position:relative}.page-title{font-size:2.2rem;font-weight:800;background:linear-gradient(135deg,var(--primary-dark),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;margin-bottom:8px}.page-subtitle{color:var(--text-muted);font-size:1rem}.sub-nav{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:28px;padding:4px;background:#8e44ad0d;border-radius:30px;justify-content:center}.sub-nav-item{padding:10px 20px;border-radius:25px;border:2px solid transparent;background:#fff;color:var(--primary);cursor:pointer;font-weight:600;font-size:.95rem;font-family:Inter,sans-serif;transition:all .25s ease}.sub-nav-item:hover{background:var(--primary-light);border-color:var(--primary)}.sub-nav-item.active{background:var(--primary);color:#fff;border-color:var(--primary)}body.dark-mode .sub-nav{background:#8e44ad26}body.dark-mode .sub-nav-item{background:#1e1e2e;color:#c39bd3}body.dark-mode .sub-nav-item.active{background:var(--primary);color:#fff}.tab-content{display:none}.tab-content.active{display:block}.section-title{font-size:1.6rem;font-weight:700;color:var(--primary-dark);margin-bottom:20px;padding-bottom:10px;border-bottom:2px solid var(--primary-light)}.card-premium{background:var(--card-bg);border:1px solid var(--border);border-radius:12px;padding:24px;box-shadow:var(--shadow);margin-bottom:24px}.card-title{font-size:1.2rem;font-weight:700;color:var(--primary-dark);margin-bottom:12px}.card-title .card-icon{display:inline-flex;align-items:center;justify-content:center;width:32px;height:32px;background:var(--primary-light);border-radius:8px;margin-right:10px;color:var(--primary)}.concept-card{background:var(--card-bg);border-left:4px solid var(--primary);border-radius:8px;padding:20px 24px;margin-bottom:20px;box-shadow:0 2px 8px #0000000a}.concept-card h3,.concept-card .concept-title{font-size:1.1rem;font-weight:700;color:var(--primary);margin:0 0 10px}.concept-card p,.concept-card li{line-height:1.75}table{width:100%;border-collapse:collapse;margin:16px 0;font-size:.95rem}th{background:var(--primary);color:#fff;padding:12px 14px;text-align:left;font-weight:600}td{padding:10px 14px;border-bottom:1px solid var(--border)}tr:nth-child(2n) td{background:#8e44ad08}tr:hover td{background:#8e44ad0f}.practice-question-card{background:var(--card-bg);border:1px solid var(--border);border-radius:10px;padding:20px;margin-bottom:18px;box-shadow:0 2px 6px #0000000a;transition:box-shadow .2s}.practice-question-card:hover{box-shadow:0 4px 14px #00000014}body.dark-mode .practice-question-card{background:#1e1e2e;border-color:#333}.practice-option-box{border:1.5px solid var(--border);border-radius:7px;padding:10px 14px;cursor:pointer;transition:all .18s;background:var(--card-bg)}.practice-option-box:hover{border-color:var(--primary);background:var(--primary-light)}body.dark-mode .practice-option-box{background:#262636;border-color:#444;color:#e0e0e0}body.dark-mode .practice-option-box:hover{border-color:#c39bd3;background:#8e44ad26}@media(max-width:768px){.practice-option-box{border:none;border-radius:0;padding:8px 0;border-bottom:1px dashed var(--border)}.practice-question-card{border:none;border-radius:0;border-bottom:3px solid var(--primary-light);box-shadow:none;padding:16px 0}}.solution-details{background:#f8f9fa;border:1px solid var(--border);border-radius:6px;padding:10px 14px;margin-top:10px}body.dark-mode .solution-details{background:#262636;border-color:#444}.solution-details summary{font-weight:700;cursor:pointer;color:var(--primary);list-style:none;user-select:none}.solution-details summary::-webkit-details-marker{display:none}.solution-details[open] summary{margin-bottom:10px}.solution-correct{color:var(--success);font-weight:700}.next-tab-btn-container{text-align:right;margin:28px 0 12px}.next-tab-btn{display:inline-flex;align-items:center;gap:8px;padding:13px 28px;background:linear-gradient(135deg,var(--primary),var(--secondary));color:#fff;border:none;border-radius:25px;font-size:1rem;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 4px 14px #8e44ad59;transition:all .2s}.next-tab-btn:hover{transform:translateY(-2px);box-shadow:0 8px 20px #8e44ad73}.test-start-scr{text-align:center;padding:40px 20px}.test-start-scr h3{font-size:1.8rem;color:var(--primary);margin-bottom:10px}body.dark-mode .test-start-scr h3{color:#c39bd3}.tinfo-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;max-width:460px;margin:20px auto}.tinfo-card{background:var(--primary-light);border-radius:10px;padding:14px;text-align:center}.tinfo-num{font-size:2rem;font-weight:900;color:var(--primary)}.tinfo-lbl{font-size:.82rem;color:var(--text-muted);margin-top:3px}.start-test-btn{padding:13px 38px;background:linear-gradient(135deg,var(--primary),var(--secondary));color:#fff;border:none;border-radius:30px;font-size:1.15rem;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 8px 20px #8e44ad66;transition:all .2s}.start-test-btn:hover{transform:translateY(-2px);box-shadow:0 12px 28px #8e44ad80}.test-hdr{display:flex;justify-content:space-between;align-items:center;background:linear-gradient(135deg,var(--primary-dark),var(--primary));color:#fff;border-radius:12px;padding:14px 22px;margin-bottom:20px}.test-tmr{font-size:2rem;font-weight:900;font-family:monospace;letter-spacing:3px}.test-tmr.urgent{color:#ff6b6b;animation:blink .8s infinite}@keyframes blink{0%,to{opacity:1}50%{opacity:.4}}.test-prog-bar{height:6px;background:var(--border);border-radius:3px;margin-bottom:20px;overflow:hidden}body.dark-mode .test-prog-bar{background:#333}.test-prog-fill{height:100%;background:linear-gradient(90deg,var(--primary),var(--secondary));border-radius:3px;transition:width .5s ease}.test-qblock{background:var(--card-bg);border:1px solid var(--border);border-radius:10px;padding:18px;margin-bottom:14px}body.dark-mode .test-qblock{background:#1e1e2e;border-color:#444}.test-qtext{font-size:.98rem;font-weight:600;color:var(--text);margin:0 0 12px;line-height:1.7}body.dark-mode .test-qtext{color:#e0e0e0}.test-qnum{display:inline-flex;align-items:center;justify-content:center;min-width:28px;height:28px;background:var(--primary);color:#fff;border-radius:50%;font-size:.78rem;font-weight:700;flex-shrink:0}.test-opts-grid{display:flex;flex-direction:column;gap:8px}.test-opt{display:flex;align-items:center;gap:10px;padding:11px 14px;border:2px solid var(--border);border-radius:8px;cursor:pointer;transition:all .2s;font-size:.93rem;font-family:Inter,sans-serif;background:var(--card-bg)}body.dark-mode .test-opt{border-color:#444;color:#e0e0e0;background:#1e1e2e}.test-opt:hover,.test-opt.sel{border-color:var(--primary);background:var(--primary-light)}.test-opt.ok{border-color:var(--success)!important;background:#27ae601f!important;pointer-events:none}.test-opt.bad{border-color:var(--danger)!important;background:#e74c3c1f!important;pointer-events:none}.test-opt.no-click{pointer-events:none}.opt-ltr{display:inline-flex;align-items:center;justify-content:center;min-width:28px;height:28px;border-radius:50%;border:2px solid var(--primary);color:var(--primary);font-weight:700;font-size:.82rem;flex-shrink:0;transition:all .2s}.test-opt.sel .opt-ltr{background:var(--primary);color:#fff}.test-opt.ok .opt-ltr{background:var(--success);border-color:var(--success);color:#fff}.test-opt.bad .opt-ltr{background:var(--danger);border-color:var(--danger);color:#fff}.test-sol-box{display:none;margin-top:10px;padding:10px 12px;background:#27ae6014;border-left:3px solid var(--success);border-radius:4px;font-size:.88rem;line-height:1.6}body.dark-mode .test-sol-box{background:#27ae601f;color:#ddd}.test-result{display:none;background:linear-gradient(135deg,var(--primary-dark),#2c3e50);color:#fff;border-radius:16px;padding:30px;text-align:center;margin-top:24px}.result-score{font-size:4rem;font-weight:900;margin:10px 0}.grade-bdg{display:inline-block;padding:5px 18px;border-radius:20px;font-size:1rem;font-weight:700;margin:10px 0}.tact-btn{padding:11px 24px;border:none;border-radius:8px;font-size:.97rem;font-weight:700;cursor:pointer;margin:5px;font-family:Inter,sans-serif;transition:all .2s}.tact-btn:hover{transform:translateY(-2px);box-shadow:0 6px 14px #0003}.badge-match{background:var(--warning);color:#fff;font-size:.72rem;padding:2px 8px;border-radius:10px;font-weight:700;margin-right:6px}.badge-multi{background:var(--primary);color:#fff;font-size:.72rem;padding:2px 8px;border-radius:10px;font-weight:700;margin-right:6px}.badge-pyq{background:var(--secondary);color:#fff;font-size:.72rem;padding:2px 8px;border-radius:10px;font-weight:700;margin-right:6px}.badge-exam{background:var(--secondary);color:#fff;font-size:.8rem;padding:3px 10px;border-radius:12px;font-weight:600;display:inline-block;margin-bottom:8px}.info-banner{padding:13px 16px;background:#3498db1a;border-left:4px solid var(--secondary);border-radius:6px;margin-bottom:22px;font-size:.93rem}@media(max-width:768px){.container{padding:10px!important;border-radius:0!important}.page-title{font-size:1.6rem}.sub-nav{gap:5px}.sub-nav-item{padding:8px 14px;font-size:.88rem}.concept-card{padding:14px;border-left-width:3px}.card-premium{padding:16px}table{font-size:.85rem}th,td{padding:8px 10px}.test-hdr{flex-direction:column;gap:8px;text-align:center}.tinfo-grid{gap:8px}.next-tab-btn{width:100%;justify-content:center}}.q-row{display:flex;gap:15px}.q-body{flex-grow:1}.q-num-badge{background:var(--primary);color:#fff;width:30px;height:30px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;flex-shrink:0}.q-header{margin-bottom:12px}.q-text{font-weight:600;font-size:1.05rem;margin:0;line-height:1.6}.q-text-sm{font-weight:600;margin-top:0;margin-bottom:15px}.q-options{display:flex;flex-direction:column;gap:8px;margin-bottom:15px}.opt-label{display:flex;cursor:pointer;width:100%}.opt-radio{margin-right:12px;margin-top:4px}.opt-radio-sm{margin-right:10px}.exam-badge{background:var(--secondary);color:#fff;padding:3px 10px;border-radius:12px;font-size:.8rem;font-weight:600;display:inline-block;margin-bottom:8px}.sol-details-alt{margin-top:15px;border:1px solid var(--secondary);border-radius:6px;padding:10px}body.dark-mode .sol-details-alt{border-color:#3d6b8c}.sol-summary-alt{cursor:pointer;color:var(--secondary);font-weight:600;outline:none;list-style:none;user-select:none}.sol-summary-alt::-webkit-details-marker{display:none}.sol-body{margin-top:10px;padding-top:10px;border-top:1px dashed #ccc}body.dark-mode .sol-body{border-top-color:#444}.sol-answer{color:var(--success);font-weight:700;margin-bottom:5px}.sol-text{font-size:.95rem;margin-top:0}.sol-list{margin-top:10px;padding-left:20px;font-size:.95rem;color:#444}body.dark-mode .sol-list{color:#bbb}.sol-list li{margin-bottom:5px;line-height:1.6}.theory-heading{color:var(--primary);margin-top:1.5rem}.theory-para{line-height:1.6;margin-bottom:1.5rem}.theory-highlight{background:#8e44ad0d;padding:15px;border-left:4px solid var(--primary);border-radius:4px;margin-top:1rem;margin-bottom:1.5rem}.theory-success-box{background:#2ecc711a;padding:10px;border-left:4px solid #2ecc71}.theory-overflow{overflow-x:auto;margin-top:1rem}.theory-overflow-mb{overflow-x:auto;margin-bottom:1.5rem}.theory-section-sep{margin-bottom:20px;padding-bottom:10px;border-bottom:2px solid var(--border)}.diff-tab-bar{display:flex;gap:10px;margin-bottom:20px;border-bottom:1px solid var(--border);padding-bottom:10px}.diff-tab-btn-inactive{padding:8px 16px;border:none;border-radius:20px;background:#eee;color:#555;cursor:pointer;font-weight:600;font-family:Inter,sans-serif}.diff-tab-btn-active{padding:8px 16px;border:none;border-radius:20px;background:var(--primary);color:#fff;cursor:pointer;font-weight:600;font-family:Inter,sans-serif}body.dark-mode .diff-tab-btn-inactive{background:#333;color:#aaa}.next-btn-row{text-align:right;margin-top:20px}.next-btn-primary{padding:10px 24px;background:var(--primary);color:#fff;border:none;border-radius:4px;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 2px 4px #0003;transition:all .2s}.next-btn-warning{padding:10px 24px;background:var(--warning);color:#fff;border:none;border-radius:4px;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 2px 4px #0003;transition:all .2s}.next-btn-success{padding:12px 24px;background:#2ecc71;color:#fff;border:none;border-radius:4px;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 4px 6px #0003;transition:all .2s}.next-btn-purple{padding:12px 24px;background:#9b59b6;color:#fff;border:none;border-radius:4px;font-weight:700;cursor:pointer;font-family:Inter,sans-serif;box-shadow:0 4px 6px #0003;transition:all .2s}.next-btn-primary:hover,.next-btn-warning:hover,.next-btn-success:hover,.next-btn-purple:hover{transform:translateY(-1px);filter:brightness(1.08)}.text-danger-bold{color:#c0392b;font-weight:700}.tab-active-bar{background:#8e44ad1a;border-bottom:2px solid var(--primary)}.tab-active-bar-blue{background:#3498db1a;border-bottom:2px solid var(--secondary)}