@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 .lesson .sec-label {margin:56px 0 20px}.legacy-content .lesson p.reveal {font-size:15px;line-height:2;color:var(--text);margin:0 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:9px 0 0}.legacy-content .doc-quote {background:var(--accent-soft);border:1px solid rgba(77,107,254,.25);border-radius:10px;padding:20px 22px;margin:12px 0 20px;font-size:14px;line-height:1.9;color:var(--text)}.legacy-content .doc-quote .q-src {display:block;margin-top:8px;font-size:12px;color:var(--sub)}.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:12px 18px;background:var(--accent-soft);color:var(--accent-deep);font:12px ui-monospace,SFMono-Regular,Menlo,monospace}.legacy-content .source pre {margin:0;padding:20px;overflow:auto}.legacy-content .source code {color:var(--text);font:12.5px/1.75 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:14px 18px;border:1px solid var(--border);border-radius:8px;background:var(--bg);font-size:12px;line-height:1.8;color:var(--sub)}.legacy-content .snapshot code {color:var(--text)}.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 .exercise {display:grid;grid-template-columns:52px 1fr;gap:18px;background:linear-gradient(135deg,#eef1ff,var(--card));border:1px solid rgba(77,107,254,.3);border-radius:14px;padding:24px;margin-top:12px}.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,.25);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 .copy-steps {margin:12px 0 20px;padding-left:22px}.legacy-content .copy-steps li {font-size:14.5px;line-height:1.95;color:var(--text);margin-bottom:10px}.legacy-content #demo-notes {background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:28px;box-shadow:var(--shadow-card);margin-top:12px}.legacy-content .nb-toolbar {display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-bottom:14px}.legacy-content .nb-btn {display:inline-flex;align-items:center;gap:8px;border:1px solid rgba(77,107,254,.4);background:var(--accent-soft);color:var(--accent-deep);border-radius:11px;padding:12px 18px;font-size:14px;font-weight:700;cursor:pointer;font-family:inherit;min-height:48px}.legacy-content .nb-btn svg {flex:0 0 auto}.legacy-content .nb-btn.primary {background:var(--accent);border-color:var(--accent);color:#fff}.legacy-content .nb-btn.scn.active {background:var(--accent);border-color:var(--accent);color:#fff}.legacy-content .nb-board {display:grid;grid-template-columns:repeat(4,1fr);gap:10px}.legacy-content .nb-col {background:var(--bg);border:1px solid var(--border);border-radius:12px;padding:10px;min-height:150px;transition:border-color .3s,box-shadow .3s}.legacy-content .nb-col.lit {border-color:var(--accent);box-shadow:0 0 0 2px rgba(77,107,254,.16)}.legacy-content .nb-col.lit-red {border-color:var(--danger);box-shadow:0 0 0 2px rgba(220,38,38,.14)}.legacy-content .nb-col-head {display:flex;justify-content:space-between;align-items:center;gap:6px;margin-bottom:8px}.legacy-content .nb-col-name {font-size:12px;font-weight:800;color:var(--text);font-family:ui-monospace,Menlo,monospace}.legacy-content .nb-count {font-size:11px;font-weight:800;color:var(--accent-deep);background:var(--accent-soft);border-radius:999px;padding:2px 9px}.legacy-content .nb-col-sub {font-size:11px;color:var(--sub);line-height:1.5;margin-bottom:8px}.legacy-content .nb-card {background:var(--card);border:1.5px solid rgba(77,107,254,.4);border-radius:10px;padding:9px 11px;font-size:11.5px;line-height:1.55;color:var(--text);box-shadow:var(--shadow-card);opacity:0;transform:translateY(8px);transition:opacity .4s,transform .4s}.legacy-content .nb-card.in {opacity:1;transform:translateY(0)}.legacy-content .nb-card .nb-status {display:block;font:800 10px/1.4 ui-monospace,Menlo,monospace;color:var(--accent-deep);margin-bottom:3px}.legacy-content .nb-card.frozen {border-color:var(--border);background:var(--bg)}.legacy-content .nb-card.frozen .nb-status {color:var(--sub)}.legacy-content .nb-card.rejected-card {border-color:rgba(220,38,38,.45)}.legacy-content .nb-card.rejected-card .nb-status {color:var(--danger)}.legacy-content .nb-gate {margin-top:14px;background:var(--bg);border:1px solid var(--border);border-radius:12px;padding:12px 14px}.legacy-content .nb-gate-title {font-size:12px;font-weight:800;color:var(--sub);margin-bottom:8px;display:flex;align-items:center;gap:6px}.legacy-content .nb-gate-title svg {color:var(--accent)}.legacy-content .nb-checks {display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.legacy-content .nb-check {display:flex;align-items:center;gap:6px;background:var(--card);border:1px solid var(--border);border-radius:8px;padding:7px 9px;font:600 11px/1.4 ui-monospace,Menlo,monospace;color:var(--sub);transition:border-color .25s,color .25s}.legacy-content .nb-check.pass {border-color:var(--success);color:var(--success)}.legacy-content .nb-check .nb-tick {width:14px;height:14px;flex:0 0 auto;display:grid;place-items:center}.legacy-content .nb-caption {display:flex;gap:9px;align-items:flex-start;margin-top:16px;background:var(--accent-soft);border:1px solid rgba(77,107,254,.25);border-radius:10px;padding:16px 18px;font-size:14px;line-height:1.8;color:var(--text);min-height:64px}.legacy-content .nb-caption svg {flex:0 0 auto;color:var(--accent);margin-top:2px}.legacy-content .nb-drawer {margin-top:14px}.legacy-content .nb-drawer-title {font-size:12px;font-weight:800;color:var(--sub);margin-bottom:8px}.legacy-content .nb-note {background:var(--bg);border:1px solid var(--border);border-radius:9px;margin-bottom:6px;overflow:hidden}.legacy-content .nb-note-btn {display:flex;align-items:center;gap:8px;width:100%;border:none;background:none;padding:10px 12px;font:600 12px/1.5 -apple-system,BlinkMacSystemFont,"PingFang SC",sans-serif;color:var(--text);cursor:pointer;text-align:left;min-height:44px}.legacy-content .nb-note-btn .nb-tag {flex:0 0 auto;font:800 10px/1 ui-monospace,Menlo,monospace;border-radius:999px;padding:4px 8px}.legacy-content .nb-tag.t-imp {color:var(--accent-deep);background:var(--accent-soft)}.legacy-content .nb-tag.t-pro {color:var(--amber);background:rgba(217,119,6,.1)}.legacy-content .nb-tag.t-rej {color:var(--danger);background:rgba(220,38,38,.08)}.legacy-content .nb-tag.t-arc {color:var(--sub);background:rgba(0,0,0,.05)}.legacy-content .nb-note-sum {display:none;padding:0 12px 11px;font-size:12.5px;line-height:1.7;color:var(--sub)}.legacy-content .nb-note.open .nb-note-sum {display:block}@media(max-width:760px){.legacy-content .facts {grid-template-columns:1fr}.legacy-content .nb-board {grid-template-columns:repeat(2,1fr)}.legacy-content .nb-checks {grid-template-columns:1fr 1fr}.legacy-content .source-head {flex-direction:column}.legacy-content .objective {grid-template-columns:1fr}.legacy-content .lesson-header:after {display:none}.legacy-content .nb-btn {flex:1 1 auto;justify-content:center}}

.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)}