@import url('https://fonts.googleapis.com/css2?family=Open+Sans:wght@400;500;700;900&family=Noto+Sans+JP:wght@400;500;700&display=swap');

:root {
  --brown: #243b53;
  --beige: #f0f4f8;
  --accent: #4a7fa5;
  --white: #ffffff;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Open Sans", "Noto Sans JP", sans-serif;
  background: var(--white);
  color: var(--brown);
  line-height: 1.9;
}

a {
  text-decoration: none;
  color: inherit;
}

button {
  font: inherit;
  cursor: pointer;
}

.header {
  height: 90px;
  padding: 0 8%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--white);
}

.logo {
  font-size: 32px;
  font-weight: 700;
  letter-spacing: -2px;
}

.logo span {
  color: var(--accent);
}

.nav {
  display: flex;
  gap: 36px;
}

.nav a {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1.5px;
  transition: color 0.3s;
}

.nav a:hover {
  color: var(--accent);
}

.nav-toggle {
  display: none;
}

.hero {
  width: 100%;
  min-height: 0;
  padding: 0;
}

.hero img {
  display: block;
  width: 100%;
  height: auto;
}

.section {
  padding: 40px 10%;
}

.section h2 {
  font-size: clamp(26px, 3vw, 38px);
  line-height: 1.6;
  margin-bottom: 24px;
}

.about {
  padding-top: 110px;
}

.about-content a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.about-content a:hover {
  color: var(--brown);
}

.research-slider {
  max-width: 1000px;
  margin: 0 auto;
}

.slider-window {
  overflow: hidden;
}

.slider-track {
  display: flex;
  transition: transform 0.5s ease;
}

.research-slide {
  flex: 0 0 100%;
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 40px;
  padding: 30px;
  background: var(--beige);
}

/* Research image */
.research-slide img {
  width: 45%;
  height: auto;
  max-height: 320px;
  object-fit: contain;
}

/* Research text */
.research-text {
  flex: 1;
  min-width: 0;
}

.research-text h3 {
  font-size: 20px;
  margin-bottom: 15px;
}

/* Research references */
.research-description {
  font-size: 15px;
  line-height: 1.9;
}

.research-reference {
  margin-top: 25px;
  font-size: 13px;
  line-height: 1.6;
}

.research-reference a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.research-reference a:hover {
  color: var(--brown);
}

/* Slider controls */
.slider-controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 30px;
  margin-top: 25px;
}

.slider-prev,
.slider-next {
  width: 45px;
  height: 45px;
  border: 1px solid var(--brown);
  border-radius: 50%;
  background: transparent;
  color: var(--brown);
  font-size: 20px;
}

.slider-prev:hover,
.slider-next:hover {
  background: var(--brown);
  color: white;
}

.slider-counter {
  font-size: 14px;
}

.misc-content a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.misc-content a:hover {
  color: var(--brown);
}

.footer {
  background: var(--brown);
  color: white;
  text-align: center;
  padding: 45px 20px;
}

.footer p {
  font-size: 11px;
  opacity: 0.7;
}

/* スマホ対応 */
@media (max-width: 768px) {
  .header {
    position: relative;
    height: 70px;
    padding: 0 6%;
  }

  .logo {
    font-size: 24px;
  }

  .nav-toggle {
    display: block;
    border: none;
    background: transparent;
    font-size: 25px;
  }

  .nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    padding: 25px;
    background: var(--white);
    flex-direction: column;
    z-index: 10;
  }

  .nav.open {
    display: flex;
  }

  .section {
    padding: 40px 7%;
  }

  .about {
    padding-top: 75px;
  }

  .research-slide {
    flex-direction: column;
    gap: 20px;
    padding: 20px;
    align-items: stretch;
  }

  .research-slide img {
    width: 100%;
    max-height: 250px;
  }
}