:root{
  --bg: #f5f3ee;
  --panel: #ffffff;
  --ink: #22201c;
  --muted: #6b6558;
  --accent: #c1440e;
  --accent-soft: #f0d9c8;
  --jp: #17324a;
  --th: #0b5d3b;
  --th-bg: #e8f5ee;
  --en: #6b6558;
  --border: #e4ddce;
  --shadow: 0 2px 10px rgba(0,0,0,.06);
  --radius: 14px;
  font-size: 18px;
}

*{box-sizing:border-box;}
html,body{margin:0;padding:0;}
body{
  background: var(--bg);
  color: var(--ink);
  font-family: "Noto Sans Thai","Noto Sans JP","Noto Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;
  line-height: 1.7;
}

a{color: var(--accent); text-decoration: none;}
a:hover{text-decoration: underline;}

.topbar{
  position: sticky; top:0; z-index: 20;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  padding: 14px 28px;
  box-shadow: var(--shadow);
}
.topbar-home{ position: static; text-align:center; padding: 40px 28px 28px; }
.back-link{ font-size: 1rem; font-weight:600; }
.doc-title{ margin: 6px 0 4px; font-size: 1.6rem; font-weight:700; }
.topbar-home .doc-title{ font-size: 2.2rem; }
.doc-meta{ color: var(--muted); font-size: .95rem; }

main.doc, main.index-main, main.gallery-grid{
  max-width: 1400px;
  margin: 0 auto;
  padding: 24px 28px 80px;
}

/* ---- slide section (course pages) ---- */
.slide-section{
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  margin-bottom: 22px;
  padding: 18px 22px 22px;
  display: grid;
  grid-template-columns: minmax(260px, 40%) 1fr;
  gap: 22px;
  align-items: start;
}
.slide-section:not(:has(img)){ grid-template-columns: 1fr; }
.slide-number{
  grid-column: 1 / -1;
  color: var(--accent);
  font-weight: 700;
  font-size: .95rem;
  letter-spacing: .02em;
}
.slide-image-wrap{ position: relative; }
.slide-image-wrap img{
  width: 100%;
  height: auto;
  border-radius: 10px;
  border: 1px solid var(--border);
  cursor: zoom-in;
  display: block;
}
.zoom-hint{
  position:absolute; right:10px; bottom:10px;
  background: rgba(0,0,0,.55); color:#fff;
  padding: 3px 10px; border-radius: 20px; font-size: .78rem;
  pointer-events:none; opacity:0; transition: opacity .15s;
}
.slide-image-wrap:hover .zoom-hint{ opacity: 1; }

.slide-text{ min-width: 0; }
.block{ margin-bottom: 14px; padding: 10px 14px; border-radius: 10px; }
.block-label{
  display:inline-block; font-size:.7rem; font-weight:700; letter-spacing:.06em;
  color: var(--muted); margin-bottom: 4px;
}
.block-jp{
  font-family:"Noto Sans JP","Noto Sans Thai",sans-serif;
  font-size: 1.35rem;
  color: var(--jp);
  background: #eef3f8;
  line-height: 2.1;
}
.block-th{
  font-size: 1.1rem;
  color: var(--th);
  background: var(--th-bg);
}
.block-en{
  font-size: 1rem;
  color: var(--en);
  background: #f4f2ec;
  font-style: italic;
}
.block-other{ font-size: .95rem; color: var(--muted); background: #f4f2ec; }

ruby{ ruby-align: center; }
rt{ font-size: .55em; color: #5a7893; user-select:none; }

.jp-word{
  cursor: pointer;
  border-bottom: 2px dotted var(--accent);
  border-radius: 3px;
  transition: background .12s;
}
.jp-word:hover{ background: var(--accent-soft); }

/* ---- index / TOC ---- */
.section-heading{
  font-size: 1.4rem; margin: 30px 0 16px; padding-bottom: 8px;
  border-bottom: 2px solid var(--border);
}
.card-grid{
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}
.course-card{
  display:flex; flex-direction:column;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform .12s, box-shadow .12s;
}
.course-card:hover{ transform: translateY(-3px); box-shadow: 0 8px 20px rgba(0,0,0,.1); text-decoration:none; }
.card-thumb{ width:100%; height:150px; object-fit: cover; display:block; background:#eee; }
.card-thumb-empty{
  display:flex; align-items:center; justify-content:center;
  color:#fff; background: linear-gradient(135deg,var(--jp),#3a5a78);
  font-weight:700; font-size:1.4rem; letter-spacing:.08em;
}
.course-card-body{ padding: 12px 14px 16px; }
.course-card-title{ font-weight:600; font-size:1rem; color:var(--ink); margin-bottom:4px;
  display:-webkit-box; -webkit-line-clamp:2; -webkit-box-orient:vertical; overflow:hidden; }
.course-card-meta{ color: var(--muted); font-size: .85rem; }

/* ---- gallery grid ---- */
main.gallery-grid{
  display:grid;
  grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
  gap: 10px;
}
.gallery-cell{ position:relative; }
.gallery-thumb{
  width:100%; aspect-ratio: 4/3; object-fit: cover;
  border-radius: 8px; border: 1px solid var(--border);
  cursor: zoom-in; display:block; background:#eee;
}
.gallery-idx{
  position:absolute; left:6px; bottom:6px;
  background: rgba(0,0,0,.6); color:#fff; font-size:.72rem;
  padding: 1px 7px; border-radius: 10px;
}

/* ---- lightbox ---- */
.lightbox{ position: fixed; inset:0; z-index: 100; display:flex; align-items:center; justify-content:center; }
.lightbox[hidden]{ display:none; }
.lightbox-backdrop{ position:absolute; inset:0; background: rgba(10,10,8,.92); }
#lightbox-img{
  position: relative; max-width: 94vw; max-height: 88vh; object-fit: contain;
  border-radius: 6px; box-shadow: 0 10px 40px rgba(0,0,0,.5);
}
.lightbox-caption{
  position:absolute; bottom: 18px; left:0; right:0; text-align:center;
  color:#fff; font-size:.9rem; opacity:.85;
}
.lb-btn{
  position:absolute; z-index:2; background: rgba(255,255,255,.12); color:#fff;
  border:none; border-radius:50%; width:48px; height:48px; font-size:1.4rem;
  cursor:pointer; display:flex; align-items:center; justify-content:center;
  transition: background .12s;
}
.lb-btn:hover{ background: rgba(255,255,255,.28); }
.lb-close{ top:18px; right:18px; }
.lb-prev{ left:18px; top:50%; transform:translateY(-50%); }
.lb-next{ right:18px; top:50%; transform:translateY(-50%); }

/* ---- word popup ---- */
.word-popup{
  position: fixed; z-index: 110; max-width: 260px;
  background: var(--panel); border: 1px solid var(--border);
  border-radius: 12px; box-shadow: 0 10px 30px rgba(0,0,0,.18);
  padding: 12px 16px;
}
.word-popup[hidden]{ display:none; }
.wp-word{ font-family:"Noto Sans JP",sans-serif; font-size: 1.3rem; font-weight:700; color: var(--jp); }
.wp-romaji{ color: var(--muted); font-size: .85rem; margin: 2px 0 6px; }
.wp-thai{ color: var(--th); font-size: 1.05rem; font-weight:600; }

@media (max-width: 760px){
  :root{ font-size: 16px; }
  .slide-section{ grid-template-columns: 1fr; }
  .topbar{ padding: 12px 16px; }
  main.doc, main.index-main, main.gallery-grid{ padding: 16px 14px 60px; }
}