/* ============================================================
   MOBILE NAV — style.cssの末尾に追記
   ============================================================ */

/* ハンバーガーボタン（モバイルのみ表示） */
.nav-burger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  background: transparent;
  border: 1px solid var(--br2);
  cursor: crosshair;
  transition: border-color 0.2s;
}
.nav-burger:hover {
  border-color: var(--g);
}
.burger-line {
  display: block;
  width: 100%;
  height: 1px;
  background: var(--ink);
  transition:
    transform 0.3s ease,
    opacity 0.3s ease;
}

/* バーガーが開いている状態 */
.nav-burger.is-open .burger-line:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.nav-burger.is-open .burger-line:nth-child(2) {
  opacity: 0;
}
.nav-burger.is-open .burger-line:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* オーバーレイ全体 */
.nav-overlay {
  position: fixed;
  inset: 0;
  z-index: 300;
  background: var(--bg);
  display: flex;
  flex-direction: column;

  /* 初期状態：非表示 */
  opacity: 0;
  pointer-events: none;
  transform: translateY(-8px);
  transition:
    opacity 0.3s ease,
    transform 0.3s ease;
}
.nav-overlay.is-open {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

/* オーバーレイ内部レイアウト */
.nav-overlay-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  position: relative;
}

/* オーバーレイ ヘッダー行 */
.nav-overlay-header {
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 22px;
  border-bottom: 1px solid var(--br2);
  flex-shrink: 0;
}
.nav-overlay-logo {
  font-family: "Shippori Mincho", serif;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.1em;
}
.nav-close {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid var(--br2);
  font-family: var(--mono);
  font-size: 13px;
  color: var(--ink3);
  cursor: crosshair;
  transition: all 0.2s;
}
.nav-close:hover {
  border-color: var(--g);
  color: var(--g);
}

/* ナビリンク一覧 */
.nav-overlay-nav {
  flex: 1;
  display: flex;
  flex-direction: column;
  border-bottom: 1px solid var(--br2);
  overflow-y: auto;
}
.nav-overlay-item {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  align-items: center;
  gap: 16px;
  padding: 28px 22px;
  text-decoration: none;
  border-bottom: 1px solid var(--br);
  transition: background 0.2s;
  position: relative;
}
.nav-overlay-item:last-child {
  border-bottom: none;
}
.nav-overlay-item:hover {
  background: var(--bg2);
}
.nav-overlay-item.current {
  background: var(--gp);
}
.nav-overlay-item.current::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--g);
}
.nav-overlay-no {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.2em;
  color: var(--ink3);
}
.nav-overlay-jp {
  font-family: "Shippori Mincho", serif;
  font-size: 22px;
  font-weight: 700;
  color: var(--ink);
}
.nav-overlay-en {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.25em;
  color: var(--ink3);
}

/* オーバーレイ CTA (TRANSFER) */
.nav-overlay-cta {
  padding: 20px 22px;
  border-bottom: 1px solid var(--br2);
  flex-shrink: 0;
}

.nav-overlay-cta .nav-overlay-item {
  border: 1px solid var(--g);
  background: var(--gp);
  padding: 20px 24px;
}

.nav-overlay-cta .nav-overlay-item:hover {
  background: var(--g);
}

.nav-overlay-cta .nav-overlay-item:hover .nav-overlay-jp,
.nav-overlay-cta .nav-overlay-item:hover .nav-overlay-en {
  color: var(--bg);
}

/* オーバーレイ フッター */
.nav-overlay-footer {
  padding: 20px 22px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  flex-shrink: 0;
}

.nav-overlay-footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.nav-overlay-count {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--ink3);
}
.nav-overlay-ig {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.15em;
  color: var(--ink3);
  text-decoration: none;
  border-bottom: 1px solid var(--br2);
  transition:
    color 0.2s,
    border-color 0.2s;
}
.nav-overlay-ig:hover {
  color: var(--g);
  border-color: var(--g);
}

/* グリッド線の装飾 */
.nav-overlay-inner::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--br) 1px, transparent 1px),
    linear-gradient(90deg, var(--br) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
  z-index: -1;
}

/* モバイルでのみ表示 */
@media (max-width: 900px) {
  .nav-burger {
    display: flex;
  }
}

/* body scroll lock（JS側でクラスを付与） */
body.nav-is-open {
  overflow: hidden;
}

/* ============================================================
   観測システム接続リンク（モバイルフッター）
   ============================================================ */
.nav-overlay-system-links {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--br2);
}

.nav-overlay-system-link {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--bg);
  border: 1px solid var(--br2);
  text-decoration: none;
  transition: all 0.2s;
  cursor: crosshair;
}

.nav-overlay-system-link:hover {
  background: var(--bg2);
  border-color: var(--g);
}

.nav-overlay-system-link:active {
  background: var(--gp);
  border-color: var(--g);
}

.system-link-jp {
  font-family: "Shippori Mincho", serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.system-link-en {
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.2em;
  color: var(--ink3);
}