/* ─── ハンバーガーメニュー ─── */
.hamburger-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: transparent;
  border: 1.5px solid var(--color-border);
  border-radius: 8px;
  cursor: pointer;
  font-size: 20px;
  line-height: 1;
  color: var(--color-text);
  margin-left: 12px;
  transition: background 0.15s, border-color 0.15s;
  font-family: inherit;
}
.hamburger-btn:hover {
  background: #f3f7fb;
  border-color: var(--color-primary);
  color: var(--color-primary);
}
.nav-menu {
  position: fixed;
  inset: 0;
  z-index: 1000;
  visibility: hidden;
  opacity: 0;
  transition: opacity 0.25s ease, visibility 0s linear 0.25s;
}
.nav-menu.is-open {
  visibility: visible;
  opacity: 1;
  transition: opacity 0.25s ease, visibility 0s linear 0s;
}
.nav-menu__overlay {
  position: absolute;
  inset: 0;
  background: rgba(20, 30, 45, 0.55);
}
.nav-menu__panel {
  position: absolute;
  top: 0; right: 0; bottom: 0;
  width: 100%;
  max-width: 460px;
  background: #fff;
  box-shadow: -4px 0 24px rgba(0,0,0,0.12);
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.3s ease;
  overflow: hidden;
}
.nav-menu.is-open .nav-menu__panel { transform: translateX(0); }
.nav-menu__header {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border);
  background: #fff;
}
.nav-menu__title {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--color-text);
}
.nav-menu__close {
  width: 36px;
  height: 36px;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  font-size: 18px;
  cursor: pointer;
  color: var(--color-text-soft);
  font-family: inherit;
  line-height: 1;
}
.nav-menu__close:hover {
  color: var(--color-text);
  border-color: var(--color-text-muted);
}
.nav-menu__body {
  flex: 1;
  overflow-y: auto;
  padding: 0 20px 24px;
  -webkit-overflow-scrolling: touch;
}
.nav-progress-summary {
  margin: 16px 0 20px;
  padding: 14px 16px;
  background: linear-gradient(90deg, #FFF8E5 0%, #FFFAEE 100%);
  border: 1.5px solid #E8C870;
  border-radius: 10px;
  font-size: 13px;
  color: #6B4D11;
  line-height: 1.6;
}
.nav-progress-summary strong { color: #B57A0E; font-size: 15px; }
.nav-progress-summary__row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.nav-progress-summary__bar {
  margin-top: 8px;
  height: 6px;
  background: #fff5d8;
  border-radius: 999px;
  overflow: hidden;
}
.nav-progress-summary__bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #E8C870, #B57A0E);
  transition: width 0.5s ease;
}
.nav-menu__section { margin: 12px 0 18px; }
.nav-menu__section-title {
  margin: 0 0 8px;
  font-size: 13px;
  font-weight: 700;
  color: var(--color-text-soft);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.nav-menu__group {
  margin: 0 0 6px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
}
.nav-menu__group > summary {
  padding: 10px 14px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  background: #fafbfd;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-menu__group > summary::-webkit-details-marker { display: none; }
.nav-menu__group > summary::after {
  content: "▸";
  color: var(--color-text-muted);
  font-size: 12px;
  transition: transform 0.2s;
}
.nav-menu__group[open] > summary::after { transform: rotate(90deg); }
.nav-menu__group ul {
  list-style: none;
  padding: 4px 0;
  margin: 0;
  background: #fff;
}
.nav-menu__item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border-bottom: 1px solid #f1f3f6;
}
.nav-menu__item:last-child { border-bottom: none; }
.nav-menu__item a {
  flex: 1;
  color: var(--color-text);
  font-size: 13.5px;
  line-height: 1.5;
  text-decoration: none;
  border: none;
}
.nav-menu__item a:hover { color: var(--color-primary); }
.nav-menu__item.is-current { background: #f3f7fb; }
.nav-menu__item.is-current a { font-weight: 600; color: var(--color-primary); }
.nav-mark {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 24px;
  height: 22px;
  padding: 0 6px;
  font-size: 11px;
  font-weight: 700;
  border-radius: 999px;
  line-height: 1;
}
.nav-mark--unread { background: transparent; color: transparent; border: 1px dashed #d8dde4; }
.nav-mark--read {
  background: #FFF1D6;
  color: #B57A0E;
  border: 1px solid #E8C870;
}
.nav-mark--perfect {
  background: #EAF3DE;
  color: #3B6D11;
  border: 1px solid #84B048;
}
@media (max-width: 700px) {
  .nav-menu__panel { max-width: 100%; }
  .nav-menu__title { font-size: 15px; }
  .nav-menu__item a { font-size: 13px; }
}
body.nav-open { overflow: hidden; }