/* ===== サブレイアウト（サイドバー＋コンテンツ） ===== */
.sub-layout {
  max-width: 1400px;
  margin: 0 auto;
  padding: 60px clamp(24px, 5vw, 80px) 80px;
  display: flex;
  gap: 60px;
  align-items: flex-start;
}

/* ===== スティッキーサイドナビ ===== */
.sub-sidenav {
  width: 230px;
  flex-shrink: 0;
  position: sticky;
  top: 96px; /* ヘッダー80px + 余白16px */
  align-self: flex-start;
  max-height: calc(100vh - 112px);
  overflow-y: auto;
}
.sub-sidenav__label {
  background: #005eb8;
  color: #fff;
  font-family: "montserrat", sans-serif;
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.2em;
  padding: 12px 0;
  text-align: center;
  margin-bottom: 8px;
}
.sub-sidenav__list {
  display: flex;
  flex-direction: column;
  gap: 0;
  padding: 8px 0;
}
.sub-sidenav__item {
  position: relative;
}
.sub-sidenav__link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 8px;
  font-size: 15px;
  font-weight: 400;
  color: #8f8f8f;
  transition: color 0.2s;
  line-height: 1.4;
}
.sub-sidenav__link::before {
  content: '－';
  font-size: 14px;
  flex-shrink: 0;
  color: inherit;
  line-height: 1;
}
.sub-sidenav__link:hover { color: #31caff; }
.sub-sidenav__item.is-active .sub-sidenav__link {
  color: #31caff;
  font-weight: 700;
}

/* ===== コンテンツエリア ===== */
.sub-content {
  flex: 1;
  min-width: 0;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1200px) {
  .sub-layout { padding: 48px clamp(24px, 4vw, 60px) 60px; gap: 40px; }
  .sub-sidenav { width: 200px; top: 90px; }
}
@media (max-width: 900px) {
  .sub-layout { gap: 28px; }
  .sub-sidenav { width: 180px; }
}
@media (max-width: 767px) {
  .sub-layout {
    flex-direction: column;
    padding: 0;
    gap: 0;
  }
  .sub-sidenav { display: none; }
  .sub-content {
    padding: 40px 24px;
    width: 100%;
    box-sizing: border-box;
  }
}
@media (max-width: 640px) {
  .sub-content { padding: 32px 16px; }
}