.op-card{background:var(--ms-panel-bg);border:1px solid var(--ms-line);border-radius:var(--ms-radius);padding:1.4rem 1.5rem;box-shadow:0 1px 3px rgba(0,0,0,0.04)}.op-head{display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap;margin-bottom:0.85rem}.op-qid{font:600 0.78rem var(--ms-font-mono);color:var(--ms-muted);letter-spacing:0.04em;text-transform:uppercase}.op-head-actions{display:flex;gap:0.5rem}.op-banner{margin:0 0 1rem;padding:0.65rem 0.95rem;font:0.92rem/1.55 var(--ms-font-sans);border-radius:var(--ms-radius-sm);border:1px solid transparent}.op-banner-ok{background:rgba(21,128,61,0.10);color:var(--xm-ok);border-color:rgba(21,128,61,0.32)}.op-banner-bad{background:rgba(185,28,28,0.08);color:var(--xm-bad);border-color:rgba(185,28,28,0.32)}.op-banner-info{background:var(--xm-accent-soft);color:var(--xm-accent-dark);border-color:rgba(99,102,241,0.32)}.op-problem{position:relative;padding:0.4rem 0 0.4rem 2.6rem;font:1.1rem/1.75"Charter","Bitstream 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var(--ms-font-sans);color:var(--ms-ink);white-space:pre-wrap}.op-print-btn{padding-left:0.7rem;padding-right:0.85rem}.op-print-btn span{margin-right:0.25rem}.op-answer-row{display:flex;align-items:center;gap:0.6rem;flex-wrap:wrap;margin:0 0 0.4rem}.op-answer-row label{font:600 0.88rem var(--ms-font-sans);color:var(--ms-ink-soft)}.op-answer-row input{flex:1 1 18rem;font:600 1rem var(--ms-font-mono);padding:0.55rem 0.8rem;border:1.5px solid var(--ms-line);border-radius:var(--ms-radius-sm);background:var(--ms-panel-bg);color:var(--ms-ink)}.op-answer-row input:focus{outline:none;border-color:var(--xm-accent);box-shadow:0 0 0 3px var(--xm-accent-soft)}.op-hint{display:block;font:0.78rem/1.45 var(--ms-font-sans);color:var(--ms-muted);margin:0 0 1rem;padding:0 0.1rem}.op-hint code{font-family:var(--ms-font-mono);font-size:0.85em;background:var(--ms-panel-bg-soft);padding:0.05rem 0.35rem;border:1px solid var(--ms-line);border-radius:4px;color:var(--ms-ink)}.op-peeked{display:flex;align-items:center;gap:0.7rem;flex-wrap:wrap;padding:0.65rem 0.9rem;margin:0 0 1rem;background:var(--xm-accent-soft);border:1px solid rgba(99,102,241,0.32);border-radius:var(--ms-radius-sm)}.op-peeked-label{font:700 0.78rem var(--ms-font-sans);color:var(--xm-accent-dark);text-transform:uppercase;letter-spacing:0.05em}.op-peeked-tex .katex{font-size:1.15em!important;color:var(--ms-ink)}.op-divider{border-top:1px dashed var(--ms-line);margin:1.1rem 0}.op-reveal-btn{width:100%;padding:0.75rem;font-size:0.95rem}.op-solution{background:var(--ms-panel-bg-soft);border:1px solid var(--ms-line);border-radius:var(--ms-radius-sm);padding:1rem 1.15rem 1.15rem}.op-solution-head{font:700 0.78rem var(--ms-font-sans);color:var(--xm-accent-dark);text-transform:uppercase;letter-spacing:0.06em;margin-bottom:0.7rem}.op-solution-body{font:0.95rem/1.65 var(--ms-font-serif,Georgia,serif);color:var(--ms-ink);white-space:pre-wrap}.op-solution-body .katex{font-size:1.02em}.op-statbar{display:flex;flex-wrap:wrap;align-items:center;gap:0.5rem 1.2rem;margin-top:1rem;padding:0.85rem 1.1rem;background:var(--ms-panel-bg-soft);border:1px solid var(--ms-line);border-radius:var(--ms-radius-sm)}.op-stat{display:flex;flex-direction:column;align-items:flex-start;gap:0.1rem;min-width:72px}.op-stat-num{font:700 1.15rem var(--ms-font-mono);color:var(--xm-accent-dark);line-height:1}.op-stat-num strong{color:var(--xm-ok)}.op-stat-lbl{font:0.7rem var(--ms-font-sans);color:var(--ms-muted);text-transform:uppercase;letter-spacing:0.05em}.op-statbar #op-stats-reset{margin-left:auto}@media (max-width:640px){.op-card{padding:1.1rem 1rem}.op-answer-row input{flex-basis:100%}.op-statbar{gap:0.4rem 0.8rem}.op-stat{min-width:60px}.op-stat-num{font-size:1rem}}.op-print-brand,.op-print-footer{display:none}@media print{@page{margin:0.7in 0.6in 0.8in}body,html{background:#fff!important;color:#000!important}.ms-hero,.ms-sidebar,.ms-sidebar-backdrop,.ms-sidebar-toggle,.ms-rail,.ms-inline-ad,.ms-title,.modern-nav,.modern-nav-header,header.modern-nav-header,nav.modern-nav,.nav-header,.ad-hero-banner,.ad-sticky-footer,.ad-init,.footer,footer,.xm-toc,.xm-seo-section,.op-head-actions,.op-answer-row,.op-reveal-btn,.op-statbar,.op-divider,.op-banner,.op-qid,#xm-share-host,.xm-modal-backdrop{display:none!important}main.ms-main{display:block!important;max-width:7in;margin:0 auto!important;padding:0!important}.ms-workspace{margin:0!important;padding:0!important}.op-print-brand{display:flex!important;align-items:baseline;justify-content:space-between;gap:0.5rem;padding-bottom:0.4rem;margin-bottom:0.6rem;border-bottom:1.5px solid #000;font-family:"Inter",-apple-system,sans-serif}.op-print-brand-mark{font-weight:700;font-size:11pt;color:#000;letter-spacing:0.02em}.op-print-brand-path{font-family:"JetBrains Mono","Courier New",monospace;font-size:9pt;color:#555}.op-card{border:0!important;background:#fff!important;padding:0!important;box-shadow:none!important}.op-problem{padding-left:2.2rem!important;font:11.5pt/1.55"Charter","Cambria",Georgia,serif!important;color:#000!important}.op-q-badge{font:700 italic 1.4rem"Instrument Serif",Georgia,serif!important;color:#000!important}.op-solution{margin-top:0.5rem!important;padding:0.5rem 0 0!important;border-top:1px dashed #888!important;background:#fff!important;border-left:0!important;border-right:0!important;border-bottom:0!important}.op-solution-head{color:#000!important;font-weight:700;margin-bottom:0.4rem}.op-solution-body{font:10.5pt/1.5"Inter",sans-serif!important;color:#000!important}.op-solution-body .katex{font-size:10.5pt!important}.xm-diagram{max-width:100%!important;page-break-inside:avoid;border:1px solid #888!important;background:#fff!important}.op-print-footer{display:block!important;margin-top:1.2rem;padding-top:0.45rem;border-top:1px solid #888;font:9pt"Inter",sans-serif;color:#555;text-align:center}a[href]::after{content:""!important}}