/* ===== Narrated lessons (30 Sep 2026): animated scenes with a teacher's voice ===== */
.np .np-stage{position:relative;background:var(--surface);padding:18px 20px 12px}
.np-head{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap;margin-bottom:6px}
.np-head h3{font-family:var(--font-sans);font-size:var(--fs-2xl);font-weight:var(--fw-h3);margin:0;color:var(--ink)}
.np-count{font-size:var(--fs-label);font-weight:var(--fw-semibold);color:var(--muted,#4B5563);background:var(--maths-soft);color:var(--maths-soft-ink);border-radius:10px;padding:3px 10px}
.np-fig{width:100%}
.np-fig svg{width:100%;height:auto;display:block;max-height:max(240px,calc(100vh - 400px));overflow:visible}
.np-fig text{font-family:var(--font-sans)}
.np-fig text.hd{font-family:var(--font-sans)}
.np-fig [data-n]{transition:opacity .45s ease,stroke .35s ease,fill .35s ease,stroke-width .35s ease}
.np-fig .h{opacity:0}
.np-fig.instant *{transition:none!important;animation:none!important}
.np-fig line.lit,.np-fig path.lit,.np-fig polyline.lit{stroke:#1D5BD8;stroke-width:9}
.np-fig line.lit-g,.np-fig path.lit-g{stroke:#12805C;stroke-width:9}
.np-fig line.lit-y,.np-fig path.lit-y{stroke:#E0A100;stroke-width:9}
.np-fig rect.lit,.np-fig polygon.lit,.np-fig circle.lit{stroke:#1D5BD8;stroke-width:6}
.np-fig rect.lit-y,.np-fig polygon.lit-y{stroke:#E0A100;stroke-width:6}
.np-fig text.lit{fill:#1D5BD8}
.np-fig text.ok{fill:#0E6B4C}
.np-fig .np-pop,.np-fig .np-pulse{transform-box:fill-box;transform-origin:center}
.np-fig .np-pop{animation:npPop .45s cubic-bezier(.3,1.5,.5,1)}
.np-fig .np-pulse{animation:npPulse .45s ease-in-out 2}
@keyframes npPop{0%{transform:scale(.3);opacity:0}100%{transform:scale(1);opacity:1}}
@keyframes npPulse{50%{transform:scale(1.2)}}
.np-start{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:rgba(255,255,255,.72)}
.np-start[hidden]{display:none}
.np-startbtn{display:inline-flex;align-items:center;gap:12px;background:var(--primary);color:#fff;border:0;border-radius:18px;padding:16px 26px 16px 20px;font:inherit;font-weight:var(--fw-semibold);font-size:var(--fs-xl);box-shadow:0 5px 0 var(--primary-lip);cursor:pointer;min-height:60px}
.np-startbtn svg{width:30px;height:30px}
.np-startbtn:active{transform:translateY(4px);box-shadow:0 1px 0 var(--primary-lip)}
.np-ask{margin-top:10px;background:var(--panel);border-radius:20px;padding:16px 18px;display:flex;flex-direction:column;gap:12px}
.np-ask[hidden]{display:none}
.np-ask .lx-q{font-size:var(--fs-xl);font-weight:var(--fw-semibold);margin:0}
.np-cap{padding:14px 22px;border-top:1px solid var(--line);min-height:86px;display:flex;align-items:center}
.np-cap p{font-size:var(--fs-lg);line-height:1.5;max-width:66ch;margin:0;color:var(--ink)}
.np-bar{display:flex;flex-wrap:wrap;gap:10px;align-items:center;padding:12px 16px;border-top:1px solid var(--line);background:var(--panel)}
.np-btn{min-height:48px;border-radius:14px;border:2px solid var(--line-strong);background:var(--surface);color:var(--ink);font:inherit;font-weight:var(--fw-semibold);font-size:var(--fs-sm);padding:0 14px;display:inline-flex;gap:8px;align-items:center;cursor:pointer}
.np-btn:hover{border-color:var(--ink)}
.np-btn.main{width:56px;height:56px;padding:0;border-radius:50%;background:var(--primary);color:#fff;border:0;box-shadow:0 4px 0 var(--primary-lip);justify-content:center}
.np-btn.main:active{transform:translateY(3px);box-shadow:0 1px 0 var(--primary-lip)}
.np-btn[aria-pressed="true"]{background:var(--maths-soft);border-color:var(--maths-fill);color:var(--maths-soft-ink)}
.np-btn:focus-visible,.np-startbtn:focus-visible{outline:3px solid var(--ink);outline-offset:3px}
.np-prog{flex:1 1 80px;min-width:60px;height:8px;background:var(--surface);border:1px solid var(--line);border-radius:99px;overflow:hidden}
.np-prog i{display:block;height:100%;width:0;background:var(--maths-fill);transition:width .4s ease}
.np-nav{display:flex;gap:10px;margin-left:auto}
@media (max-width:620px){
  .np .np-stage{padding:14px 12px 10px}
  .np-btn span{display:none}
  .np-btn{padding:0 12px}
  .np-cap{padding:12px 14px}
  .np-cap p{font-size:var(--fs-md)}
  .np-nav{width:100%;justify-content:space-between;margin-left:0}
}
@media (prefers-reduced-motion:reduce){.np-fig *{animation:none!important}}
@media (min-width:900px){
  .np-stage.asking{display:grid;grid-template-columns:minmax(0,1.3fr) minmax(300px,1fr);column-gap:22px;align-items:center}
  .np-stage.asking .np-head{grid-column:1 / -1}
  .np-stage.asking .np-ask{margin-top:0}
  .np-stage.asking .options{grid-template-columns:1fr 1fr}
}
.np-credit{margin:8px 4px 0;font-size:var(--fs-meta);color:var(--ink-2,#4B5563)}