#tailtiu-crossing-boundaries{--cb-green:#24783d;--cb-deep:#153f2d;--cb-orange:#d86724;--cb-paper:#f8fbf8;--cb-border:#d9e7dd;max-width:950px;margin:0 auto;color:#173527;font:normal 16px/1.6 system-ui,-apple-system,Segoe UI,Arial,sans-serif;scroll-margin-top:24px}
#tailtiu-crossing-boundaries *{box-sizing:border-box}
#tailtiu-crossing-boundaries h1,#tailtiu-crossing-boundaries h2,#tailtiu-crossing-boundaries h3{color:var(--cb-deep);line-height:1.22;margin:0 0 .65em}
#tailtiu-crossing-boundaries h1{font-size:clamp(2rem,4.5vw,3rem)}
#tailtiu-crossing-boundaries h2{font-size:clamp(1.35rem,3vw,1.7rem)}
#tailtiu-crossing-boundaries h3{font-size:1.12rem;margin-top:1.35em}
#tailtiu-crossing-boundaries p{margin:.65em 0 1em}#tailtiu-crossing-boundaries a{color:var(--cb-green)}
#tailtiu-crossing-boundaries .cb-hero{padding:1.9rem;border-radius:18px;background:linear-gradient(125deg,#e8f4e9,#fff7f0);margin-bottom:1rem;border:1px solid var(--cb-border)}
#tailtiu-crossing-boundaries .cb-kicker{color:var(--cb-green);font-size:.77rem;font-weight:800;letter-spacing:.08em}
#tailtiu-crossing-boundaries .cb-subtitle{font-weight:650;color:#4e7158}
#tailtiu-crossing-boundaries .cb-scorebar{display:flex;justify-content:space-between;flex-wrap:wrap;gap:.5rem;border-top:1px solid var(--cb-border);padding-top:.75rem;margin-top:1rem}
#tailtiu-crossing-boundaries .cb-toc{background:#f0f7f1;border:1px solid var(--cb-border);border-radius:14px;padding:1rem;margin:0 0 1.5rem}
#tailtiu-crossing-boundaries .cb-toc>div{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:.7rem}
#tailtiu-crossing-boundaries .cb-toc a{background:white;border:1px solid #d8e7dd;border-radius:99px;padding:.3rem .65rem;text-decoration:none;font-size:.86rem}
#tailtiu-crossing-boundaries .cb-panel{padding:clamp(1.1rem,3vw,2rem);background:white;border:1px solid var(--cb-border);border-radius:16px;margin-bottom:1.1rem;scroll-margin-top:12px}
#tailtiu-crossing-boundaries .cb-video-slot{background:#e5ede7;aspect-ratio:16/9;display:grid;place-items:center;border-radius:12px;overflow:hidden}
#tailtiu-crossing-boundaries .cb-video-slot iframe{border:0;width:100%;height:100%}
#tailtiu-crossing-boundaries .cb-video-placeholder{text-align:center;display:grid;gap:.4rem;padding:1.2rem;max-width:33rem}
#tailtiu-crossing-boundaries details{margin-top:1rem;padding:0.9rem;background:#f7faf8;border-radius:10px;border:1px solid #e1ece3}
#tailtiu-crossing-boundaries summary{font-weight:700;cursor:pointer}#tailtiu-crossing-boundaries .cb-transcript-body{padding:.5rem .3rem}
#tailtiu-crossing-boundaries .cb-formula{padding:.65rem 1rem;border-left:4px solid var(--cb-orange);background:#fffaf4}
#tailtiu-crossing-boundaries .cb-activity-head{display:flex;align-items:baseline;justify-content:space-between;gap:.5rem;flex-wrap:wrap}
#tailtiu-crossing-boundaries .cb-activity-head span{color:#5c7664;font-size:.88rem}
#tailtiu-crossing-boundaries .cb-question{min-width:0;margin:1rem 0;border:1px solid #dae6dd;border-radius:11px;padding:1rem;background:#fff}
#tailtiu-crossing-boundaries .cb-question legend{font-weight:650;padding:0 .3rem;max-width:100%;white-space:normal}
#tailtiu-crossing-boundaries .cb-qid{font:700 .8rem system-ui,sans-serif;background:#edf6ed;color:#246b39;border-radius:5px;padding:.2rem .4rem;margin-right:.3rem}
#tailtiu-crossing-boundaries .cb-options{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,260px),1fr));gap:.55rem;margin-top:.3rem}
#tailtiu-crossing-boundaries .cb-option{display:flex;align-items:flex-start;gap:.6rem;padding:.7rem .8rem;border:1px solid #d5e1d8;border-radius:9px;cursor:pointer}
#tailtiu-crossing-boundaries .cb-option:has(input:checked){background:#ebf6ed;border-color:var(--cb-green)}
#tailtiu-crossing-boundaries input[type=radio]{accent-color:var(--cb-green);margin-top:.3rem;flex:none}
#tailtiu-crossing-boundaries .cb-answer-feedback{border-left:3px solid #a1b9a7;padding:.45rem .7rem;margin:.65rem 0 0;background:#f4f8f5}
#tailtiu-crossing-boundaries .cb-answer-feedback.cb-incorrect{border-color:var(--cb-orange);background:#fff7f1}
#tailtiu-crossing-boundaries .cb-actions{display:flex;align-items:center;flex-wrap:wrap;gap:.7rem;margin-top:1.2rem}
#tailtiu-crossing-boundaries button{border:0;border-radius:9px;padding:.7rem 1rem;font:600 .96rem system-ui;cursor:pointer;background:var(--cb-green);color:white}
#tailtiu-crossing-boundaries button.cb-reset{background:#eaf2ed;color:var(--cb-deep)}
#tailtiu-crossing-boundaries button:focus-visible,#tailtiu-crossing-boundaries a:focus-visible,#tailtiu-crossing-boundaries summary:focus-visible{outline:3px solid var(--cb-orange);outline-offset:3px}
#tailtiu-crossing-boundaries .cb-block-score{font-weight:750;color:var(--cb-deep)}
#tailtiu-crossing-boundaries .cb-muted,#tailtiu-crossing-boundaries .cb-version{font-size:.9rem;color:#58705d}
#tailtiu-crossing-boundaries .cb-footer{padding:1rem 1.5rem;border-top:2px solid var(--cb-green)}
@media(max-width:600px){#tailtiu-crossing-boundaries .cb-hero,#tailtiu-crossing-boundaries .cb-panel{padding:1rem}#tailtiu-crossing-boundaries .cb-options{grid-template-columns:1fr}#tailtiu-crossing-boundaries .cb-video-slot{aspect-ratio:16/10}}
@media(prefers-reduced-motion:reduce){#tailtiu-crossing-boundaries *{scroll-behavior:auto!important}}

/* v1.0 technical publication update: two-video, stage-scoped playback layout. */
#tailtiu-crossing-boundaries {max-width:1100px;padding:0 10px;}
#tailtiu-crossing-boundaries .cb-video-slot{background:#e5ede7;aspect-ratio:16/9;overflow:hidden;border-radius:12px;position:relative;}
#tailtiu-crossing-boundaries .cb-video-slot iframe{display:block;width:100%;height:100%;border:0;}
#tailtiu-crossing-boundaries .cb-video-external{font-size:.89rem;margin:.45rem 0 .8rem;color:#526958}
#tailtiu-crossing-boundaries .cb-teacher-link{font-size:.88rem;margin-bottom:0}
#tailtiu-crossing-boundaries .cb-story-questions{min-width:0}
#tailtiu-crossing-boundaries .cb-story-grid{margin:0 0 1.1rem}
#tailtiu-crossing-boundaries .cb-story-grid .cb-panel{margin-bottom:1.1rem}
#tailtiu-crossing-boundaries .cb-toc div{row-gap:.45rem;}
@media (min-width:1000px) and (min-height:700px){
 #tailtiu-crossing-boundaries .cb-story-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.03fr);gap:1rem;align-items:start}
 #tailtiu-crossing-boundaries .cb-story-video{position:sticky;top:12px;align-self:start;}
 html.cb-embedded #tailtiu-crossing-boundaries .cb-story-video{position:static;}
}
@media (max-width:999px){#tailtiu-crossing-boundaries .cb-story-video{position:static}}