:root {
  --blue-900: #0a2a4a;
  --blue-800: #0d3b66;
  --blue-700:#135c9b;
  --blue-600:#1b75c5;
  --blue-100: #eaf3ff;
  --border: #d9e6f5;
  --maxw: 1100px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header,
footer {
  background: var(--blue-800);
  color: #fff;
}

/* ===== Header ===== */
.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 12px 18px;
  min-height: 4rem;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 12px;
}

.title {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

/* clamp()で端末幅に応じて自然に縮む */
.title-main {
  font-size: clamp(1.25rem, 2.4vw, 2rem);
  font-weight: 700;
  line-height: 1.15;
}

.title-sub {
  font-size: clamp(.85rem, 1.6vw, 1rem);
  font-weight: 700;
  opacity: .95;
}

.language {
  display: flex;
  align-items: flex-end;
}

.lang-toggle {
  display: inline-flex;
  gap: 8px;
  flex-wrap: wrap;
  /* かなり狭い場合に折り返す */
  justify-content: flex-end;
}

.lang-toggle button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 6rem;
  padding: .5rem .75rem;
  border: 1px solid rgba(255, 255, 255, .35);
  background: rgba(255, 255, 255, .08);
  color: #fff;
  border-radius: 999px;
  cursor: pointer;
}

.lang-toggle button[aria-pressed="true"] {
  background: #fff;
  color: var(--blue-900);
  border-color: #fff;
}

/* language switch */
.lang {
  display: none;
}

html[data-lang="ja"] .lang-ja {
  display: inline;
}

html[data-lang="en"] .lang-en {
  display: inline;
}

/* ===== Menu ===== */
.menubar {
  background: var(--blue-100);
}

.menu {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 6px 18px;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  gap: 8px;
  font-size: .9rem;
  font-weight: 600;
  flex-wrap: nowrap;
}

.menu a {
  /* flex: 0 0 auto; */
  flex: 1;
  color: var(--blue-800);
  padding: .35rem .7rem;
  border-radius: 999px;
  text-decoration: none;
  white-space: nowrap;
  /* 改行禁止 */
}

.menu a:hover,
.menu a.active {
  background: #fff;
  box-shadow: 0 4px 10px rgba(10, 42, 74, .08);
}

.contents {
  flex: 1;
}

/* ===== Top MV ===== */
.top-mv {
  position: relative;
  /* 画面が小さいほど低く、大きいほど高く */
  height: clamp(320px, 52vw, 520px);
  overflow: hidden;
  background: #000;
}

.top-mv__slider_wrap,
.top-mv__slider {
  position: absolute;
  inset: 0;
}

.top-mv__slider__elm {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 900ms ease;
}

.top-mv__slider__elm img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.top-mv__slider__elm.is-airfoil img {
  object-position: 0% 50%;
}

.top-mv__slider__elm.is-deltawing img {
  object-position: 50% 100%;
}

.top-mv__slider__elm.is-cavity img {
  object-position: 50% 100%;
}

.top-mv__slider__elm.is-cavitySound img {
  object-position: 50% 100%;
}

.top-mv__slider__elm:first-child,
.top-mv__slider__elm.is-active {
  opacity: 1;
}

/* overlay */
.top-mv::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(0, 0, 0, .55) 0%, rgba(0, 0, 0, .25) 55%, rgba(0, 0, 0, .10) 100%);
  z-index: 1;
}

.overview {
  max-width: var(--maxw);
  margin: 20px auto;
  padding: clamp(12px, 2.2vw, 18px) clamp(14px, 2.6vw, 22px);
  background-color: var(--blue-100);
  border-radius: 16px;
}

.overview .lang {
  font-size: clamp(1rem, 2.2vw, 1.35rem);
  font-weight: bold;
  line-height: 1.35;
  max-width: 900px;
}

/* ===== News ===== */
.news-title {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 1rem 18px 1rem;
  font-size: clamp(1.2rem, 2.2vw, 1.5rem);
  font-weight: 700;
}

.news-list {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 18px 24px;
  list-style: none;
}

.news-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #fff;
  margin-bottom: 1rem;
}

.news-date {
  font-weight: 700;
  color: var(--blue-800);
}

footer {
  text-align: center;
  font-size: .88rem;
  padding: 10px 0;
}

.research {
  max-width: var(--maxw);
  margin: 20px auto;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.research-title {
  width: 100%;
  max-width: var(--maxw);
  padding: 12px 18px;
  background: var(--blue-800);
  color: #fff;
  font-size: clamp(1.0rem, 2.2vw, 1.2rem);
  font-weight: bold;
}

.research-overview {
  width: 100%;
  max-width: var(--maxw);
  padding: 1rem 18px;
  font-size: 1rem;
}

.research-container {
  width: 100%;
  max-width: var(--maxw);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  padding: 1rem 18px;
}

.research-items {
  background-color: var(--blue-100);
}

.research-images {
  padding: 10px;
  text-align: center;
}

@media (max-width: 600px) {
  .research-container {
    grid-template-columns: 1fr;
  }
}

.research-captions{
  background-color: var(--blue-700);
  color: #fff;
  font-size: 1.3rem;
  text-align: center;
  font-weight: bold;
}

.research-images img {
  display: block;
  width: 100%;
  max-width: 420px;
  height: auto;
  margin: 0 auto;
}

.research-container.single {
  grid-template-columns: 1fr;  /* ← これが重要 */
}

.research-images.large-center {
  display: flex;
  justify-content: center;
  align-items: center;
}

.research-images.large-center img {
  width: 100%;
  max-width: 800px;   /* 好きな大きさに調整 */
}

/* ===== Responsive breakpoints ===== */

/* タブレット以下：ヘッダーを縦積み寄りに */
@media (max-width: 900px) {
  .header-inner {
    align-items: flex-start;
  }
}

/* スマホ：ヘッダーは縦積み、ボタンは左寄せでもOKに */
@media (max-width: 600px) {
  .header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .language {
    width: 100%;
    justify-content: flex-start;
  }

  .lang-toggle button {
    width: auto;
  }

  /* NEWSの2カラム→1カラム */
  .news-item {
    grid-template-columns: 1fr;
  }

  .news-date {
    opacity: .9;
  }

  .map-container {
    max-width: var(--maxw);
    margin: 0 auto 30px;
    padding: 0 18px;
  }

  .map-container iframe {
    width: 100%;
    height: 420px;
    border-radius: 14px;
    border: 1px solid var(--border);
  }
}