:root {
  --ground: #FAF8F4;
  --ink: #22303A;
  --accent: #0D6B68;
  --accent-soft: #0d6b6820;
  --line: #d8d2c6;
  --card: #ffffff;
  --muted: #6b7681;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--ground);
  color: var(--ink);
  font-family: Georgia, 'Iowan Old Style', 'Times New Roman', serif;
  font-size: 17px;
  line-height: 1.65;
}
#app { max-width: 1100px; margin: 0 auto; padding: 2rem 1.25rem 6rem; }
h1, h2, h3 { font-weight: 600; line-height: 1.25; }
h1 { font-size: 1.7rem; }
h2 { font-size: 1.3rem; }
a { color: var(--accent); }
button {
  font: inherit; cursor: pointer;
  background: var(--accent); color: #fff;
  border: none; border-radius: 6px; padding: 0.55rem 1.2rem;
}
button.ghost { background: transparent; color: var(--accent); border: 1px solid var(--accent); }
button:disabled { opacity: 0.45; cursor: default; }
textarea, input {
  font: inherit; width: 100%; padding: 0.6rem 0.7rem;
  border: 1px solid var(--line); border-radius: 6px; background: var(--card); color: var(--ink);
}
textarea { min-height: 7rem; resize: vertical; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 1.4rem 1.6rem; margin: 1.1rem 0; }
.muted { color: var(--muted); font-size: 0.92rem; }
.error { color: #a33; margin: 0.5rem 0; }
.layout { display: grid; grid-template-columns: 200px 1fr 260px; gap: 1.5rem; }
@media (max-width: 900px) { .layout { grid-template-columns: 1fr; } .rail, .notebook { position: static !important; } }
.rail { position: sticky; top: 1rem; align-self: start; }
.rail-item { display: flex; gap: 0.55rem; align-items: baseline; padding: 0.45rem 0.6rem; border-radius: 6px; margin-bottom: 2px; font-size: 0.95rem; }
.rail-item.current { background: var(--accent-soft); font-weight: 600; }
.rail-item.locked { color: var(--muted); }
.rail-item .dot { font-size: 0.8rem; }
.notebook { position: sticky; top: 1rem; align-self: start; background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 1rem 1.1rem; font-size: 0.92rem; max-height: 80vh; overflow-y: auto; }
.notebook h3 { margin-top: 0; font-size: 1rem; }
.notebook .nb-entry { border-top: 1px solid var(--line); padding-top: 0.6rem; margin-top: 0.6rem; }
.hook { font-size: 1.15rem; }
.phase-label { text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.75rem; color: var(--accent); font-family: -apple-system, sans-serif; }
.material { margin: 1rem 0; }
.material img { max-width: 100%; border-radius: 6px; }
.material .src { color: var(--muted); font-size: 0.85rem; }
.chat { display: flex; flex-direction: column; gap: 0.7rem; margin: 1rem 0; }
.msg { padding: 0.7rem 1rem; border-radius: 10px; max-width: 85%; }
.msg.student { background: var(--accent-soft); align-self: flex-end; }
.msg.companion { background: var(--card); border: 1px solid var(--line); align-self: flex-start; }
.reveal-card { border-left: 4px solid var(--accent); }
.wc { font-size: 0.82rem; color: var(--muted); text-align: right; font-family: -apple-system, sans-serif; }
table { border-collapse: collapse; width: 100%; font-size: 0.92rem; background: var(--card); }
th, td { border: 1px solid var(--line); padding: 0.45rem 0.7rem; text-align: left; }
th { background: var(--accent-soft); font-family: -apple-system, sans-serif; font-size: 0.82rem; }
pre.brief { white-space: pre-wrap; background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 1.2rem; font-size: 0.85rem; overflow-x: auto; }
.topbar { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 1rem; gap: 1rem; flex-wrap: wrap; }
blockquote { border-left: 3px solid var(--line); margin-left: 0; padding-left: 1rem; color: var(--muted); }
code { font-size: 0.9em; background: var(--accent-soft); padding: 0.05em 0.3em; border-radius: 4px; }
audio { width: 100%; }
.interactive-fallback { background: var(--accent-soft); border-radius: 8px; padding: 1rem; font-size: 0.9rem; }
.book-hour { border: 1px solid var(--line); background: var(--card); border-radius: 8px; padding: 0.55rem 0.7rem; margin-bottom: 0.8rem; font-size: 0.95rem; }
.book-hour a { font-weight: 600; text-decoration: none; }
.reading .reading-body { max-width: 42rem; }
.reading .reading-body h1 { font-size: 1.5rem; }
.reading .reading-body h2 { font-size: 1.2rem; margin-top: 2rem; }
.reading .reading-body p.cut { text-align: center; color: var(--muted); letter-spacing: 0.2em; }
.reading .reading-done { display: flex; gap: 1rem; align-items: center; flex-wrap: wrap; }