/* =========================================
   Coursebook (Moleskine style) — FULL CSS
   ========================================= */

:root{
  --ink:#1a1b1e;
  --paper:#CDE7D8;
  --dot:#e7e2d6;
  --accent:#2f80ed;
  --border:#2b2e33;
  --shadow:0 22px 46px rgba(0,0,0,.14), 0 4px 14px rgba(0,0,0,.08);
}

@font-face{
  font-family:'Futura';
  src:url('../fonts/futura.ttf') format('truetype');
  font-weight:400;
  font-style:normal;
}

*{box-sizing:border-box}
html,body{min-height:100%}
body{
  margin:0;
  font-family:'Futura', Arial, sans-serif;
  color:var(--ink);
  background:#f4f5f7;
  display:flex; flex-direction:column;
  padding:16px;
}

/* ===== Notebook shell ===== */
.notebook{
  display:flex;
  width:100%;
  max-width:1200px;
  margin:0 auto 24px;
  border-radius:18px;
  overflow:hidden;
  box-shadow:var(--shadow);
  background:var(--paper);
}
.spine{ width:68px; background:#0f1012; }

/* Page (cream + dots) */
.page{
  flex:1;
  padding:24px 24px 32px;
  display:flex; flex-direction:column; gap:22px;
  background:
    radial-gradient(circle at 0 0, var(--dot) 1px, transparent 2px) 0 0/28px 28px,
    radial-gradient(circle at 14px 14px, var(--dot) 1px, transparent 2px) 0 0/28px 28px,
    var(--paper);
}

/* Title plaque */
.label{
  width:min(92%, 1100px);
  margin:0 auto;
  background:#fff; border:3px solid var(--border); border-radius:26px;
  text-align:center; padding:16px 20px;
}
.label h1{ margin:0; font-weight:700; letter-spacing:.02em; font-size:clamp(1.8rem,2.2vw + 1rem,2.8rem); }
.label h2{ margin:.35rem 0 0; font-weight:600; color:#000000; font-size:clamp(1rem,.6vw + .9rem,1.35rem); }

/* Back link */
.back{ display:block; text-align:center; margin:-4px auto 8px; color:var(--accent); text-decoration:none; font-size:1.05rem; }
.back:hover{ text-decoration:underline; }

/* ===== Collapsible sheets ===== */
.sheet{
  width:min(92%, 1100px);
  margin:0 auto;
  border:3px solid var(--border);
  border-radius:22px;
  background:#fff;
  overflow:hidden;
}
.collapsible > summary{
  display:flex; align-items:center; gap:.5rem;
  cursor:pointer; list-style:none;
  padding:14px 18px; font-weight:700; user-select:none;
}
.collapsible > summary::-webkit-details-marker{ display:none; }
.collapsible > summary .caret{
  width:0; height:0; border-left:6px solid var(--ink);
  border-top:6px solid transparent; border-bottom:6px solid transparent;
  transition:transform .2s ease;
}
.collapsible[open] > summary .caret{ transform:rotate(90deg); }
.collapsible[open] > summary{ border-bottom:1px solid #e9ecef; }
.section-body{ padding:18px; }

/* ===== Slideshow ===== */
.slideshow{
  position:relative; max-width:100%; margin:0 auto;
  overflow:hidden; border-radius:16px; border:2px solid var(--border); background:#fff;
  aspect-ratio:16/9;
}
.slides{ width:100%; height:100%; }
.slides img{ width:100%; height:100%; object-fit:contain; display:none; background:#000; }
.slides img.active{ display:block; }
.slideshow .prev, .slideshow .next{
  position:absolute; top:50%; transform:translateY(-50%);
  background:rgba(0,0,0,.55); color:#fff; border:0;
  padding:10px 16px; cursor:pointer; border-radius:50%;
  font-size:1.2rem; line-height:1; opacity:0; transition:opacity .25s; pointer-events:none;
}
.slideshow:hover .prev, .slideshow:hover .next{ opacity:1; pointer-events:auto; }
.slideshow .prev{ left:10px; } .slideshow .next{ right:10px; }
.slideshow .prev:hover, .slideshow .next:hover{ background:rgba(0,0,0,.75); }
.slideshow .prev:focus-visible, .slideshow .next:focus-visible, .slideshow .fs:focus-visible{ outline:2px solid var(--accent); outline-offset:2px; }
.slideshow .fs{
  position:absolute; top:10px; right:10px; background:rgba(0,0,0,.55);
  color:#fff; border:0; padding:8px 10px; cursor:pointer; border-radius:8px; font-size:1rem;
}
.slideshow .counter{
  position:absolute; bottom:10px; right:12px;
  color:#fff; background:rgba(0,0,0,.45); padding:4px 8px; border-radius:6px; font-size:.95rem;
}
.slideshow:fullscreen{ background:#000; border-radius:0; border:none; }
.slideshow:fullscreen .prev, .slideshow:fullscreen .next{ top:50%; }
.slideshow:fullscreen .fs{ top:14px; right:14px; }

/* ===== Audio ===== */
.audio-box{ background:#f1f3f5; border:1px solid #dfe3e8; border-radius:12px; padding:10px 12px; }
.audio-box audio{ width:100%; display:block; }

/* ===== Transcript (clean box) ===== */
.transcript-toggle{
  margin-top:12px;
  border:1px solid #e0e0e0;
  border-radius:10px;
  background:#fffefc;
}
.transcript-toggle > summary{
  cursor:pointer;
  list-style:none;
  padding:10px 14px;
  font-weight:700;
}

.transcript{
  font-size: 0.98rem;
  line-height: 1.6;
  padding: 1rem 1.5rem;
  background:#fff;
  border:1px solid #e0dccc;
  border-radius:8px;
  box-shadow: inset 0 0 8px rgba(0,0,0,.05);
}

.transcript p{ margin:12px 0; }

/* ===== Video wrapper ===== */
.video{ position:relative; padding-bottom:56.25%; height:0; overflow:hidden; border-radius:12px; }
.video iframe{ position:absolute; inset:0; width:100%; height:100%; border:0; }
.video-fallback{ margin:.6rem 0 0; }

/* ===== Footer ===== */
.logos{ width:100%; text-align:center; margin:24px 0 12px; }
.logos img{ max-height:90px; max-width:90%; height:auto; width:auto; opacity:.95; }
.logos a.back{ display:block; margin-top:8px; }

/* ===== Mobile tweaks ===== */
@media (max-width:720px){
  body{ padding:12px; }
  .notebook{ flex-direction:column; border-radius:12px; }
  .spine{ width:100%; height:16px; }
  .page{ padding:12px 12px 20px; gap:16px; }
  .label, .sheet{ width:calc(100% - 24px); }
  .logos img{ max-height:70px; }
  .slideshow .prev, .slideshow .next{
    opacity:1; pointer-events:auto; padding:6px 10px; font-size:1rem;
  }
}

.video-link{
  padding:1rem;
  background:#fff;
  border:2px solid var(--border);
  border-radius:12px;
  text-align:center;
}
.video-link a{
  font-weight:700;
  color:#2f80ed;
  text-decoration:none;
}
.video-link a:hover{ text-decoration:underline; }