/* shared sidebar — edit once, applies to all chapter pages */

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 28px 0;
  border-right: 1px solid var(--border);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.sidebar::-webkit-scrollbar {
  width: 6px;
}
.sidebar::-webkit-scrollbar-thumb {
  background: rgba(15, 15, 20, 0.1);
  border-radius: 3px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 20px 20px;
  margin-bottom: 8px;
}
.brand-icon {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  object-fit: contain;
  display: block;
}
.brand-title {
  font-size: 15px;
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.01em;
}

.top-nav {
  display: flex;
  flex-direction: column;
  padding: 0 12px 12px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 16px;
}
.top-nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: 8px;
  font-size: 13.5px;
  color: var(--text-soft);
  font-weight: 600;
  border-bottom: none;
  transition: background 120ms ease;
  text-decoration: none;
}
.top-nav-item:hover {
  background: var(--bg-soft);
  color: var(--text);
  border-bottom: none;
}
.top-nav-item .ico {
  font-size: 15px;
  opacity: 0.85;
}

.ch-nav {
  display: flex;
  flex-direction: column;
  gap: 22px;
  padding: 0 12px 24px;
}
.ch-block {
  display: flex;
  flex-direction: column;
}
.ch-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 4px 12px 6px;
  border-bottom: none;
  color: var(--text);
  font-weight: 800;
  font-size: 13.5px;
  text-decoration: none;
}
.ch-head:hover {
  border-bottom: none;
  color: var(--accent-strong);
}
.ch-head .ch-num {
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 700;
  letter-spacing: 0.04em;
  min-width: 22px;
}
.ch-head .ch-name {
  line-height: 1.4;
}
.ch-block.current .ch-head .ch-num,
.ch-block.current .ch-head .ch-name {
  color: var(--accent-strong);
}
.ch-block.upcoming .ch-head {
  opacity: 0.4;
}
.ch-block.upcoming .ch-head .ch-name::after {
  content: " · 준비 중";
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
}

.sub {
  list-style: none;
  padding: 0;
  margin: 6px 0 0 22px;
  border-left: 1px solid var(--border);
}
.sub li {
  margin: 0;
}
.sub a {
  display: block;
  padding: 7px 14px;
  font-size: 13px;
  line-height: 1.45;
  color: var(--text-muted);
  font-weight: 500;
  border-left: 2px solid transparent;
  margin-left: -1px;
  border-bottom: none;
  transition: all 120ms ease;
  text-decoration: none;
}
.sub a:hover {
  color: var(--text);
  background: var(--bg-soft);
  border-bottom: none;
}
.sub a.active {
  color: var(--accent-strong);
  font-weight: 700;
  border-left-color: var(--accent-strong);
  background: var(--accent-bg);
}

.view-toggle {
  margin: 16px 16px 8px;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  font-size: 12px;
  color: var(--text-muted);
  box-shadow: var(--shadow-sm);
}
body.student-view .view-toggle {
  display: none;
}
.view-toggle code {
  color: var(--accent-strong);
  background: var(--accent-bg);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 11px;
}
.view-toggle a {
  color: var(--text);
  font-weight: 700;
  border-bottom: none;
  text-decoration: none;
}
.open-student-btn {
  display: block;
  width: 100%;
  margin-top: 10px;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid rgba(124, 58, 237, 0.2);
  background: var(--accent-bg);
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  font-family: inherit;
  transition: background 120ms ease;
}
.open-student-btn:hover {
  background: rgba(124, 58, 237, 0.15);
}