@keyframes _si{to{opacity:1}}

.legacy-content .lesson-header {position:relative;overflow:hidden}.legacy-content .lesson-header:after {content:"";position:absolute;right:-70px;top:-70px;width:220px;height:220px;border:1px solid rgba(77,107,254,.22);border-radius:50%;box-shadow:0 0 0 26px rgba(77,107,254,.04),0 0 0 52px rgba(77,107,254,.025)}.legacy-content .sec-label {margin:56px 0 20px}.legacy-content .objective {display:grid;grid-template-columns:auto 1fr;gap:16px;align-items:center;background:linear-gradient(135deg,var(--accent-soft),rgba(255,255,255,.75));border:1px solid rgba(77,107,254,.28);border-radius:var(--radius);padding:24px;margin:24px 0 32px}.legacy-content .objective svg {color:var(--accent)}.legacy-content .objective b {display:block;color:var(--accent);margin-bottom:6px}.legacy-content .objective span {font-size:14px;line-height:1.9;color:var(--text)}.legacy-content .facts {display:grid;grid-template-columns:1fr;gap:20px;margin-top:20px}.legacy-content .fact {background:var(--card);border:1px solid var(--border);border-radius:12px;padding:24px;box-shadow:var(--shadow-card)}.legacy-content .fact code {color:var(--accent);font-weight:800}.legacy-content .fact p {font-size:14px;line-height:1.9;color:var(--sub);margin:10px 0 0}.legacy-content .struct {background:var(--card);border:1px solid rgba(77,107,254,.25);border-radius:16px;padding:24px;box-shadow:var(--shadow-card)}.legacy-content .struct svg {width:100%;height:auto;display:block}.legacy-content .struct-caption {font-size:12px;color:var(--sub);text-align:center;margin-top:10px}.legacy-content .source {background:var(--card);border:1px solid var(--border);border-radius:14px;overflow:hidden;margin-top:12px;box-shadow:var(--shadow-card)}.legacy-content .source-head {display:flex;justify-content:space-between;gap:12px;padding:10px 16px;background:var(--accent-soft);color:var(--accent-deep);font:12px ui-monospace,SFMono-Regular,Menlo,monospace}.legacy-content .source pre {margin:0;padding:18px;overflow:auto}.legacy-content .source code {color:var(--text);font:12.5px/1.68 ui-monospace,SFMono-Regular,Menlo,monospace;background:none;padding:0}.legacy-content .kw {color:#3450d4}.legacy-content .ty {color:#7c3aed}.legacy-content .fn {color:#0891b2}.legacy-content .cm {color:#9ca3af}.legacy-content .str {color:#16a34a}.legacy-content .snapshot {margin-top:14px;padding:13px 16px;border:1px solid var(--border);border-radius:8px;background:var(--bg);font-size:12px;line-height:1.7;color:var(--sub)}.legacy-content .snapshot code {color:var(--text)}.legacy-content .exercise {display:grid;grid-template-columns:52px 1fr;gap:18px;background:linear-gradient(135deg,#f0f3ff,var(--card));border:1px solid rgba(77,107,254,.3);border-radius:14px;padding:24px;margin-top:16px}.legacy-content .exercise-num {width:46px;height:46px;border-radius:12px;background:var(--accent);color:white;display:grid;place-items:center;font-weight:900}.legacy-content .exercise h3 {margin:0 0 10px;color:var(--text);font-size:16px}.legacy-content .exercise p {margin:0;color:var(--sub);font-size:14px;line-height:1.9}.legacy-content .takeaway {margin-top:32px;padding:24px;border-radius:14px;background:var(--accent-soft);border:1px solid rgba(77,107,254,.28);color:var(--text);display:flex;gap:14px;line-height:1.9}.legacy-content .takeaway svg {flex:0 0 auto;color:var(--accent)}.legacy-content .takeaway b {color:var(--accent-deep)}.legacy-content p.body {font-size:15px;line-height:2;color:var(--text);margin:0 0 20px}.legacy-content .src-note {font-size:12.5px;color:var(--sub);line-height:1.8;margin:-8px 0 20px}.legacy-content .src-note code {font-size:11.5px}.legacy-content .brand-i {flex:none;line-height:1;vertical-align:-2px;margin-right:6px}.legacy-content #demo-orch {background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow-card);margin-top:16px}.legacy-content .or-bar {display:flex;flex-wrap:wrap;gap:12px;align-items:center;margin-bottom:16px}.legacy-content .or-btn {display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:44px;padding:8px 14px;border-radius:10px;border:1px solid rgba(77,107,254,.35);background:var(--accent-soft);color:var(--accent-deep);font:600 13px/1.2 -apple-system,BlinkMacSystemFont,"PingFang SC",sans-serif;cursor:pointer;transition:background .2s,border-color .2s}.legacy-content .or-btn.primary {background:var(--accent);border-color:var(--accent);color:#fff}.legacy-content .or-btn svg {flex:none}.legacy-content .or-ctrl {display:flex;gap:12px;margin-left:auto}.legacy-content .or-dots {display:flex;gap:6px;align-items:center}.legacy-content .or-dot {width:10px;height:10px;border-radius:50%;border:1.5px solid rgba(77,107,254,.45);background:transparent;transition:background .25s}.legacy-content .or-dot.done {background:var(--accent);border-color:var(--accent)}.legacy-content .or-dot.cur {background:rgba(77,107,254,.35)}.legacy-content .or-scene {border:1px solid rgba(77,107,254,.28);background:var(--bg);border-radius:12px;padding:16px 18px;margin-bottom:16px}.legacy-content .or-scene .sc-tag {font:800 11px/1 ui-monospace,Menlo,monospace;color:var(--accent-deep);background:var(--accent-soft);border-radius:5px;padding:4px 7px;display:inline-block;margin-bottom:8px}.legacy-content .or-scene .sc-text {font-size:15px;font-weight:700;line-height:1.7;color:var(--text)}.legacy-content .or-grid {display:grid;grid-template-columns:repeat(4,1fr);gap:10px}.legacy-content .or-card {border:1.5px solid var(--border);background:var(--card);border-radius:12px;padding:12px;cursor:pointer;text-align:left;font-family:inherit;transition:border-color .2s,box-shadow .2s,background .2s;min-height:44px}.legacy-content .or-card b {display:flex;align-items:center;gap:6px;font-size:13.5px;color:var(--text)}.legacy-content .or-card b svg {color:var(--accent);flex:none}.legacy-content .or-card span {display:block;font-size:11.5px;line-height:1.6;color:var(--sub);margin-top:5px}.legacy-content .or-card:hover {border-color:rgba(77,107,254,.5)}.legacy-content .or-card.right {border-color:var(--success);background:rgba(22,163,74,.06);box-shadow:0 0 0 2px rgba(22,163,74,.15)}.legacy-content .or-card.wrong {border-color:var(--danger);background:rgba(220,38,38,.05);animation:orShake .45s ease}@keyframes orShake{0%,100%{transform:translateX(0)}25%{transform:translateX(-5px)}55%{transform:translateX(5px)}80%{transform:translateX(-2px)}}.legacy-content .or-verdict {margin-top:16px;min-height:72px;padding:16px 18px;border-radius:10px;background:var(--accent-soft);border:1px solid rgba(77,107,254,.22);font-size:14px;line-height:1.8;color:var(--text)}.legacy-content .or-verdict b {color:var(--accent-deep)}.legacy-content .or-verdict .ok {color:var(--success);font-weight:800}.legacy-content .or-verdict .ng {color:var(--danger);font-weight:800}.legacy-content .or-note {font-size:12px;color:var(--sub);margin-top:10px;line-height:1.7}@media(max-width:760px){.legacy-content .facts {grid-template-columns:1fr}.legacy-content .or-grid {grid-template-columns:1fr 1fr}.legacy-content .objective {grid-template-columns:1fr}.legacy-content .lesson-header:after {display:none}.legacy-content .or-ctrl {margin-left:0;width:100%}.legacy-content .or-ctrl .or-btn {flex:1}.legacy-content .source-head {flex-direction:column}}

.legacy-content .xa-tldr {margin:18px 0 4px;padding:14px 18px;background:rgba(0,102,255,0.04);border:1px solid rgba(0,102,255,0.16);border-radius:10px}.legacy-content .xa-tldr .xa-tldr-tag {display:block;font-size:11px;font-weight:800;letter-spacing:1px;color:var(--accent,#0066ff);margin-bottom:6px}.legacy-content .xa-tldr p {margin:0;font-size:15px;line-height:1.8;color:var(--text,#1f2937)}