.bt-problem{--st-bg:#0c0a09;--st-fg:#f5f5f4;--st-fg-muted:#f5f5f4b8;--st-fg-subtle:#f5f5f480;--st-fg-faint:#f5f5f43d;--st-border:#f5f5f42e;--bt-accent:#38bdf8;background:var(--st-bg);color:var(--st-fg);padding:clamp(80px,10vw,150px) 0 clamp(72px,8vw,120px);position:relative}.bt-problem-head{max-width:780px}.bt-problem-head .st-h2{margin-bottom:24px}.bt-problem-lead{color:var(--st-fg-muted);margin:0;font-size:clamp(1.05rem,1.5vw,1.28rem);line-height:1.6}.bt-problem-lead strong{color:var(--st-fg);font-weight:600}.bt-flow{margin:clamp(44px,6vw,80px) 0 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0;font-size:12px}.bt-stats{grid-template-columns:repeat(4,1fr);gap:clamp(20px,3vw,40px);margin:clamp(48px,6vw,84px) 0 clamp(56px,7vw,96px);display:grid}.bt-stat{border-top:1px solid var(--st-border);padding-top:20px}.bt-stat-num{font-family:var(--font-display);letter-spacing:-.02em;color:var(--st-fg);font-size:clamp(2.4rem,5vw,3.8rem);font-weight:620;line-height:1;display:block}.bt-stat-num.is-accent{color:var(--bt-accent)}.bt-stat-label{font-family:var(--font-mono);letter-spacing:.04em;color:var(--st-fg-muted);margin-top:12px;font-size:12.5px;line-height:1.45;display:block}.bt-verdict{max-width:900px}.bt-verdict-quote{font-family:var(--font-display);letter-spacing:-.015em;margin:0 0 22px;font-size:clamp(1.7rem,3.4vw,3rem);font-weight:560;line-height:1.14}.bt-verdict-cite{font-family:var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--st-fg-subtle);font-size:12.5px}@media (max-width:760px){.bt-stats{grid-template-columns:repeat(2,1fr);gap:28px 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strong{color:var(--st-fg);font-weight:600}.bt-pipe-steps{flex-direction:column;gap:clamp(30px,4.5vw,60px);display:flex;position:relative}.bt-pipe-rail-bg,.bt-pipe-rail-fill{border-radius:2px;width:2px;position:absolute;top:23px;bottom:23px;left:31px}.bt-pipe-rail-bg{background:var(--bt-faint)}.bt-pipe-rail-fill{background:var(--bt-accent);transform-origin:top;transform:scaleY(1)}.bt-pipe-packet{background:var(--bt-accent);width:12px;height:12px;box-shadow:0 0 0 5px color-mix(in srgb, var(--bt-accent) 22%, transparent);opacity:0;border-radius:50%;position:absolute;top:17px;left:26px}.bt-pipe-step{grid-template-columns:64px 1fr;align-items:start;gap:clamp(16px,2.5vw,36px);display:grid;position:relative}.bt-pipe-marker{z-index:1;background:var(--st-bg);border:1.5px solid var(--st-border);width:46px;height:46px;font-family:var(--font-mono);letter-spacing:.02em;color:var(--st-fg-subtle);border-radius:50%;justify-content:center;align-items:center;margin:0 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