:root {
  --green-950: #003f2d;
  --green-900: #064d37;
  --green-800: #0b6243;
  --green-600: #27804f;
  --green-300: #8fb56d;
  --navy: #0d2f63;
  --ink: #17201d;
  --muted: #617069;
  --line: #dbe4df;
  --soft: #f4f8f5;
  --white: #ffffff;
  --shadow: 0 18px 50px rgba(8, 55, 37, 0.10);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--white);
  font-family: "Noto Sans JP", sans-serif;
  line-height: 1.75;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
.container { width: min(1180px, calc(100% - 40px)); margin: 0 auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255,255,255,.94);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(0,0,0,.05);
}
.nav-wrap {
  height: 84px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: .86rem;
  font-weight: 600;
}
.brand img { width: 166px; height: auto; }
.main-nav { display: flex; align-items: center; gap: 34px; font-size: .92rem; }
.main-nav a { position: relative; }
.main-nav a:not(.nav-cta)::after {
  content: "";
  position: absolute;
  left: 0; right: 100%; bottom: -8px;
  height: 2px;
  background: var(--green-600);
  transition: .25s ease;
}
.main-nav a:hover::after { right: 0; }
.nav-cta {
  padding: 12px 20px;
  background: var(--green-900);
  color: #fff;
  border-radius: 5px;
}
.menu-toggle { display: none; border: 0; background: none; padding: 8px; }
.menu-toggle span { display: block; width: 26px; height: 2px; background: var(--green-950); margin: 5px; }

.hero {
  min-height: 690px;
  position: relative;
  isolation: isolate;
  display: flex;
  align-items: center;
  background: url("assets/hero-renewables.jpg") center/cover no-repeat;
  overflow: hidden;
}
.hero-overlay {
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(90deg, rgba(255,255,255,.98) 0%, rgba(255,255,255,.90) 35%, rgba(255,255,255,.22) 66%, rgba(255,255,255,.05) 100%);
}
.hero-content { padding: 80px 0 120px; }
.eyebrow, .kicker, .section-heading span, .mission-content > span {
  font-weight: 700;
  letter-spacing: .18em;
  color: var(--green-600);
  font-size: .78rem;
}
.hero h1 {
  margin: 16px 0 20px;
  font-family: "Noto Serif JP", serif;
  font-weight: 600;
  color: var(--green-950);
  font-size: clamp(2.6rem, 5.3vw, 5.25rem);
  line-height: 1.28;
  letter-spacing: .02em;
}
.hero-copy { font-size: 1.06rem; font-weight: 500; }
.hero-actions { display: flex; gap: 14px; margin-top: 32px; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 180px;
  padding: 13px 20px;
  border-radius: 5px;
  font-weight: 600;
  transition: transform .2s ease, box-shadow .2s ease;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.btn-primary { color: #fff; background: var(--green-900); }
.btn-secondary { border: 1px solid var(--green-800); background: rgba(255,255,255,.84); color: var(--green-900); }
.hero-curve {
  position: absolute;
  left: -5%;
  right: -5%;
  bottom: -70px;
  height: 150px;
  background: #fff;
  border-radius: 50% 50% 0 0;
  border-top: 11px solid rgba(78, 133, 67, .85);
}

.section { padding: 96px 0; }
.section-soft { padding: 92px 0; background: var(--soft); }
.section-heading { max-width: 720px; margin: 0 auto 48px; text-align: center; }
.section-heading h2, .about-copy h2, .contact h2 {
  margin: 8px 0 14px;
  color: var(--green-950);
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.3;
}
.section-heading p { color: var(--muted); }

.service-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.service-card {
  padding: 30px 26px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fff;
  box-shadow: 0 10px 30px rgba(0,0,0,.04);
}
.service-icon {
  width: 56px; height: 56px; display: grid; place-items: center;
  border-radius: 50%; background: var(--green-900); color: #fff; font-size: 1.5rem;
}
.service-card h3 { margin: 18px 0 10px; color: var(--green-900); font-size: 1.08rem; }
.service-card p { margin: 0; color: var(--muted); font-size: .92rem; }

.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 70px; align-items: center; }
.about-copy p { color: var(--muted); }
.text-link { display: inline-block; margin-top: 18px; font-weight: 700; color: var(--green-800); }
.about-image img { width: 100%; aspect-ratio: 4/3; object-fit: cover; border-radius: 20px; box-shadow: var(--shadow); }

.field-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 18px; }
.field-card { text-align: center; padding: 28px 16px; border-top: 2px solid var(--green-300); }
.field-symbol {
  height: 84px;
  display: grid;
  place-items: center;
  font-size: 2.7rem;
  line-height: 1;
  color: var(--green-800);
}
.field-icon { width: 84px; height: 84px; object-fit: contain; display: block; }
.field-card h3 { margin: 16px 0 4px; font-size: 1rem; }
.field-card p { margin: 0; color: var(--muted); font-size: .82rem; }

.mission {
  position: relative;
  isolation: isolate;
  min-height: 510px;
  display: flex;
  align-items: center;
  overflow: hidden;
  color: #fff;
}
.mission-bg {
  position: absolute;
  inset: 0;
  z-index: -2;
  background: url("assets/solar-project.jpg") center/cover no-repeat;
}
.mission::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(90deg, rgba(0,63,45,.94), rgba(0,63,45,.48));
}
.mission-content { padding: 90px 0; }
.mission-content > span { color: #cbdca7; }
.mission h2 {
  margin: 12px 0 18px;
  font-family: "Noto Serif JP", serif;
  font-size: clamp(2rem, 4.3vw, 4rem);
  line-height: 1.45;
}
.mission p { max-width: 650px; }

.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 70px; align-items: start; }
.contact-card {
  padding: 34px;
  background: var(--green-950);
  color: #fff;
  border-radius: 16px;
}
.contact-card p { margin: 0 0 15px; }
.contact-card a { text-decoration: underline; text-underline-offset: 4px; }

.site-footer { background: #003628; color: #fff; padding: 28px 0; }
.footer-grid { display: flex; align-items: center; justify-content: space-between; gap: 30px; }
.footer-grid img { width: 140px; filter: brightness(0) invert(1); opacity: .95; }
.footer-grid p { margin: 0; font-size: .82rem; }
.back-to-top { position: fixed; right: 24px; bottom: 24px; z-index: 40; width: 48px; height: 48px; border: 1px solid rgba(255,255,255,.7); border-radius: 50%; background: var(--green-900); color: #fff; box-shadow: 0 10px 26px rgba(0, 63, 45, .24); font: inherit; font-size: 1.5rem; line-height: 1; cursor: pointer; transition: transform .2s ease, background .2s ease; }
.back-to-top:hover { background: var(--green-800); transform: translateY(-3px); }
.back-to-top:focus-visible { outline: 3px solid var(--green-300); outline-offset: 3px; }

@media (max-width: 980px) {
  .brand span { display: none; }
  .main-nav { gap: 18px; }
  .service-grid { grid-template-columns: repeat(2, 1fr); }
  .field-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 760px) {
  .nav-wrap { height: 72px; }
  .brand img { width: 132px; }
  .menu-toggle { display: block; }
  .main-nav {
    position: absolute;
    top: 72px; left: 0; right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 16px 20px 22px;
    background: #fff;
    border-bottom: 1px solid var(--line);
  }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 12px 0; }
  .nav-cta { margin-top: 8px; text-align: center; }
  .hero { min-height: 620px; background-position: 67% center; }
  .hero-overlay { background: linear-gradient(90deg, rgba(255,255,255,.98), rgba(255,255,255,.76)); }
  .hero h1 { font-size: 2.55rem; }
  .hero-actions { flex-direction: column; align-items: flex-start; }
  .service-grid, .about-grid, .contact-grid { grid-template-columns: 1fr; }
  .about-grid, .contact-grid { gap: 38px; }
  .field-grid { grid-template-columns: repeat(2, 1fr); }
  .section, .section-soft { padding: 72px 0; }
  .footer-grid { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 480px) {
  .container { width: min(100% - 28px, 1180px); }
  .service-grid, .field-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 2.15rem; }
}

.language-switcher {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  white-space: nowrap;
  font-size: .78rem;
  color: var(--muted);
}
.language-switcher button {
  border: 0;
  padding: 4px 2px;
  background: transparent;
  color: inherit;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}
.language-switcher button.active {
  color: var(--green-900);
  text-decoration: underline;
  text-underline-offset: 4px;
}

@media (max-width: 980px) {
  .main-nav { gap: 14px; }
}
@media (max-width: 760px) {
  .language-switcher {
    justify-content: center;
    padding: 14px 0 2px;
    font-size: .86rem;
  }
}