/* Reset & variables */
:root {
  --color-text: #1a1a1a;
  --color-bg: #ffffff;
  --color-bg-alt: #f5f5f5;
  --color-border: #e0e0e0;
  --color-accent: #1a1a1a;
  --font-main: 'Hina Mincho', serif;
  --container-max: 960px;
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --transition-short: 150ms ease;
}

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

body {
  margin: 0;
  font-family: var(--font-main);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

/* Smooth language switch */
main {
  transition: opacity var(--transition-short);
  position: relative;
  overflow: hidden;
  margin-bottom: 0;
  padding-bottom: 0;
}

main.lang-switching {
  opacity: 0.97;
}

/* Section transitions - all absolute to prevent layout shift */
main > .section {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s cubic-bezier(0.4, 0, 0.2, 1),
              visibility 0.4s;
  pointer-events: none;
  min-height: 100%;
}

main.view-hero > .section-hero,
main.view-about > .section-about,
main.view-features > .section-features,
main.view-cta > .section-cta {
  z-index: 1;
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  position: relative !important;
}

.header .nav-link.active {
  text-decoration: underline;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* Header */
.header {
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
  background: #848884;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.25rem var(--space-md);
  gap: var(--space-lg);
}

.logo {
  font-size: 1.25rem;
  font-weight: 400;
  color: #ffffff;
  text-decoration: none;
  letter-spacing: 0.02em;
}

.logo:hover {
  text-decoration: underline;
}

.logo-link {
  display: flex;
  align-items: center;
  text-decoration: none;
  transition: opacity var(--transition-short);
}

.logo-link:hover {
  opacity: 0.85;
  text-decoration: none;
}

.logo-img {
  height: 120px;
  width: auto;
  display: block;
  background: transparent;
  margin-left: -10px;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
}

.nav {
  display: flex;
  gap: var(--space-lg);
}

.nav a {
  color: #ffffff;
  text-decoration: none;
  font-size: 1rem;
}

.nav a:hover {
  text-decoration: underline;
}

.lang-toggle {
  display: flex;
  gap: 0;
  border: 1px solid rgba(255, 255, 255, 0.4);
  border-radius: 2px;
  overflow: hidden;
}

.lang-btn {
  font-family: var(--font-main);
  font-size: 0.875rem;
  padding: var(--space-xs) var(--space-sm);
  background: transparent;
  color: #ffffff;
  border: none;
  cursor: pointer;
  transition: background var(--transition-short), color var(--transition-short);
}

.lang-btn:first-child {
  border-right: 1px solid rgba(255, 255, 255, 0.4);
}

.lang-btn:hover {
  background: rgba(255, 255, 255, 0.1);
}

.lang-btn.active,
.lang-btn[aria-pressed="true"] {
  background: #ffffff;
  color: #1a1a1a;
  font-weight: 500;
}

/* Hero */
.hero {
  padding: 0;
  margin: 0;
  line-height: 0;
}

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

.btn {
  display: inline-block;
  font-family: var(--font-main);
  font-size: 1rem;
  padding: var(--space-sm) var(--space-lg);
  text-decoration: none;
  border: 1px solid var(--color-accent);
  transition: background var(--transition-short), color var(--transition-short);
}

.btn-primary {
  background: var(--color-accent);
  color: var(--color-bg);
}

.btn-primary:hover {
  background: var(--color-text);
  color: var(--color-bg);
}

/* About */
.about {
  padding: var(--space-xl) var(--space-md);
  background: var(--color-bg-alt);
}

.about-content-box {
  max-width: 900px;
  margin: 0 auto;
  padding: var(--space-xl);
  background: var(--color-bg);
  border-radius: 24px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.about-box-title {
  margin: 0 0 var(--space-lg);
  font-family: 'Hina Mincho', serif;
  font-size: 1.5rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  line-height: 1.4;
}

.about-box-text {
  margin: 0;
  font-family: 'Noto Sans JP', sans-serif;
  font-size: 1.0625rem;
  line-height: 1.8;
  opacity: 0.9;
  white-space: pre-line;
}

.about-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  max-width: 900px;
  margin: 0 auto;
}

.about-card {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  padding: var(--space-lg);
  background: var(--color-bg);
  border-radius: 24px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.about-card.reverse {
  flex-direction: row-reverse;
}

.about-card-image {
  flex-shrink: 0;
  width: 200px;
  height: 200px;
  border-radius: 12px;
  overflow: hidden;
  background: var(--color-bg-alt);
}

.about-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.about-card-content {
  flex: 1;
}

.about-card-title {
  margin: 0 0 var(--space-sm);
  font-size: 1.5rem;
  font-weight: 400;
  letter-spacing: 0.02em;
}

.about-card-desc {
  margin: 0;
  font-family: 'Noto Sans JP', sans-serif;
  font-size: 1.0625rem;
  line-height: 1.7;
  opacity: 0.9;
}

/* Features */
.features {
  padding: var(--space-xl) var(--space-md);
  background: var(--color-bg-alt);
}

.section-title {
  margin: 0 0 var(--space-lg);
  font-size: 1.5rem;
  font-weight: 400;
  text-align: center;
  letter-spacing: 0.02em;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.feature-card:nth-child(4) {
  grid-column: 1 / -1;
  max-width: 100%;
}

.feature-card {
  padding: var(--space-lg);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  min-width: 0; /* allow shrinking so text can wrap in grid */
}

.feature-num {
  display: block;
  font-size: clamp(0.8125rem, 1.5vw, 0.875rem);
  color: var(--color-text);
  opacity: 0.6;
  margin-bottom: var(--space-sm);
}

.feature-title {
  margin: 0 0 var(--space-sm);
  font-size: clamp(1.0625rem, 2vw, 1.25rem);
  font-weight: 400;
  line-height: 1.4;
}

.feature-desc {
  margin: 0;
  font-size: clamp(0.9375rem, 1.2vw, 1rem);
  line-height: 1.6;
  opacity: 0.9;
  font-family: 'Noto Sans JP', sans-serif;
}

.feature-composition {
  font-family: 'Noto Sans JP', sans-serif;
}

.feature-composition p {
  margin: 0 0 var(--space-sm);
}

.composition-list {
  list-style: none;
  padding: 0;
  margin: var(--space-sm) 0 var(--space-md);
  font-size: clamp(0.8125rem, 1.2vw, 0.9375rem);
  line-height: 1.8;
  font-family: 'Courier New', monospace;
}

.composition-list li {
  margin: 0.25rem 0;
  white-space: nowrap;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.btn-certificate {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-main);
  font-size: 0.9375rem;
  padding: var(--space-sm) var(--space-md);
  background: var(--color-accent);
  color: var(--color-bg);
  text-decoration: none;
  border: 1px solid var(--color-accent);
  transition: background var(--transition-short), color var(--transition-short);
  margin-top: var(--space-sm);
}

.btn-certificate:hover {
  background: var(--color-text);
  border-color: var(--color-text);
}

.btn-certificate svg {
  flex-shrink: 0;
}

/* CTA / Contact form */
.cta {
  padding: var(--space-xl) var(--space-md) calc(var(--space-xl) * 2);
  min-height: 600px;
  background: var(--color-bg-alt);
}

.cta-title {
  margin-bottom: var(--space-lg);
}

.contact-form {
  max-width: 560px;
  margin: 0 auto;
  text-align: left;
}

.contact-form .form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.contact-form .form-group {
  margin-bottom: var(--space-md);
}

.contact-form .form-group-full {
  grid-column: 1 / -1;
}

.contact-form label {
  display: block;
  font-size: 0.9375rem;
  margin-bottom: var(--space-xs);
  color: var(--color-text);
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  font-family: var(--font-main);
  font-size: 1rem;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  transition: border-color var(--transition-short);
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--color-accent);
}

.contact-form textarea {
  resize: vertical;
  min-height: 120px;
}

.contact-form .form-actions {
  margin-top: var(--space-lg);
}

.contact-form .btn {
  cursor: pointer;
  border: none;
}

.contact-form .btn[type="submit"] {
  min-width: 140px;
}

/* Footer */
.footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-lg) var(--space-md);
  background: var(--color-bg);
}

.footer-info {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
}

.footer-info-item {
  margin: 0;
  font-size: 0.9375rem;
}

.footer-info-item > .footer-info-item {
  margin-bottom: var(--space-md);
}

.footer-info-item > .footer-info-item:last-child {
  margin-bottom: 0;
}

.footer-label {
  display: block;
  font-size: 0.8125rem;
  opacity: 0.7;
  margin-bottom: var(--space-xs);
}

.footer-value {
  color: var(--color-text);
  text-decoration: none;
}

a.footer-value:hover {
  text-decoration: underline;
}

.footer-copy {
  margin: 0;
  font-size: 0.875rem;
  opacity: 0.8;
  text-align: center;
}

/* Responsive */
@media (max-width: 900px) and (min-width: 769px) {
  .features-grid {
    grid-template-columns: 1fr 1fr 1fr;
  }
  
  .feature-card:nth-child(4) {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .header-inner {
    flex-wrap: wrap;
  }

  .logo-img {
    height: 50px;
  }

  .nav {
    order: 3;
    width: 100%;
    justify-content: center;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .feature-card:nth-child(4) {
    grid-column: auto;
  }

  .feature-card {
    padding: var(--space-md);
  }

  .feature-title {
    font-size: 1.125rem;
  }

  .feature-desc {
    font-size: 0.9375rem;
  }

  .feature-composition p,
  .composition-list {
    font-size: 0.8125rem;
  }

  .about-card {
    flex-direction: column !important;
    text-align: center;
  }

  .about-content-box {
    padding: var(--space-lg);
  }

  .about-box-title {
    font-size: 1.25rem;
  }

  .about-box-text {
    font-size: 1rem;
  }

  .about-card-image {
    width: 100%;
    max-width: 280px;
    height: 240px;
  }

  .footer-info {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  .hero,
  .about,
  .features,
  .cta {
    padding-left: var(--space-sm);
    padding-right: var(--space-sm);
  }

  .hero {
    min-height: 100vh;
    background-size: cover;
    background-position: center;
  }

  .contact-form .form-row {
    grid-template-columns: 1fr;
  }
}