/* ================================================================
   39 Engineering LLC. — Stylesheet
   ================================================================ */

/* ----------------------------------------------------------------
   CSS Custom Properties — Light Mode (default)
---------------------------------------------------------------- */
:root {
  /* Colors */
  --color-bg: #fafaf8;
  --color-surface: #ffffff;
  --color-surface-alt: #f4f2ec;
  --color-text: #1a1917;
  --color-text-muted: #5a5850;
  --color-text-subtle: #8a877e;
  --color-accent: #b84800;
  --color-accent-hover: #d85800;
  --color-border: #e4e0d8;
  --color-border-light: #eeebe4;

  /* Header */
  --color-header-bg: rgba(250, 250, 248, 0.92);
  --color-header-border: rgba(228, 224, 216, 0.8);

  /* Hero */
  --hero-bg-image: url('hero-light.webp');
  --hero-overlay: linear-gradient(120deg,
      rgba(15, 8, 30, 0.72) 0%,
      rgba(15, 8, 30, 0.45) 45%,
      rgba(15, 8, 30, 0.10) 80%,
      transparent 100%);

  /* Typography */
  --font-sans: 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Yu Gothic',
    'Noto Sans JP', 'BIZ UDPGothic', system-ui, sans-serif;
  --font-mono: 'SF Mono', 'SFMono-Regular', 'Menlo', 'Consolas',
    'Liberation Mono', monospace;

  /* Spacing */
  --section-padding: 6rem 1.5rem;
  --inner-max-width: 1080px;

  /* Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Transitions */
  --transition: 0.2s ease;
}

/* ----------------------------------------------------------------
   Dark Mode Overrides
---------------------------------------------------------------- */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0c0e1a;
    --color-surface: #131520;
    --color-surface-alt: #181b2c;
    --color-text: #e8e5dd;
    --color-text-muted: #8c8880;
    --color-text-subtle: #5a5752;
    --color-accent: #ff9f5a;
    --color-accent-hover: #ffb870;
    --color-border: #272a3c;
    --color-border-light: #1e2030;

    --color-header-bg: rgba(12, 14, 26, 0.94);
    --color-header-border: rgba(39, 42, 60, 0.9);

    --hero-bg-image: url('hero-dark.webp');
    --hero-overlay: linear-gradient(120deg,
        rgba(4, 6, 16, 0.82) 0%,
        rgba(4, 6, 16, 0.55) 45%,
        rgba(4, 6, 16, 0.15) 80%,
        transparent 100%);
  }
}

/* ----------------------------------------------------------------
   Reset & Base
---------------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.732;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img,
svg {
  display: block;
  max-width: 100%;
}

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

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

ul,
ol {
  list-style: none;
}

em {
  font-style: normal;
  font-weight: 600;
}

/* ----------------------------------------------------------------
   Typography Scale
---------------------------------------------------------------- */
h1,
h2,
h3,
h4 {
  line-height: 1.3;
  font-weight: 700;
  letter-spacing: -0.02em;
}

/* ----------------------------------------------------------------
   Layout Helpers
---------------------------------------------------------------- */
.section-inner {
  max-width: var(--inner-max-width);
  margin: 0 auto;
  padding: var(--section-padding);
}

.section-header {
  text-align: center;
  margin-bottom: 3.5rem;
}

.section-en {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--color-text);
}

.section-ja {
  margin-top: 0.4rem;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
}

.d-pc-none {
  display: none;
}

/* ----------------------------------------------------------------
   Buttons
---------------------------------------------------------------- */
.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-decoration: none;
  transition: background-color var(--transition), color var(--transition), border-color var(--transition);
  cursor: pointer;
}

.btn-primary {
  background-color: var(--color-accent);
  color: #ffffff;
  border: 2px solid transparent;
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  color: #ffffff;
}

.btn-secondary {
  background-color: transparent;
  color: rgba(255, 255, 255, 0.9);
  border: 2px solid rgba(255, 255, 255, 0.5);
}

.btn-secondary:hover {
  background-color: rgba(255, 255, 255, 0.12);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.7);
}

/* ----------------------------------------------------------------
   SITE HEADER
---------------------------------------------------------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--color-header-bg);
  border-bottom: 1px solid var(--color-header-border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.site-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 64px;
}

/* Logo */
.site-logo {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
  text-decoration: none;
  color: var(--color-text);
  line-height: 1;
  font-family: var(--font-mono);
}

.logo-number {
  font-size: 1.7rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--color-accent);
  line-height: 1;
}

.logo-text {
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--color-text);
}

.logo-llc {
  font-weight: 400;
  color: var(--color-text-muted);
}

/* Nav */
.site-nav ul {
  display: flex;
  gap: 0.25rem;
}

.site-nav a {
  display: block;
  padding: 0.4rem 0.75rem;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background-color var(--transition);
}

.site-nav a:hover {
  color: var(--color-text);
  background-color: var(--color-border-light);
}

/* Hamburger */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  border-radius: var(--radius-sm);
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ----------------------------------------------------------------
   HERO
---------------------------------------------------------------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-image: var(--hero-bg-image);
  background-size: cover;
  background-position: right center;
  background-repeat: no-repeat;
  z-index: 0;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: var(--hero-overlay);
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: var(--inner-max-width);
  width: 100%;
  margin: 0 auto;
  padding: 8rem 1.5rem 4rem;
}

.hero-title {
  font-size: clamp(2rem, 5.5vw, 3rem);
  font-weight: 800;
  line-height: 1.25;
  color: #ffffff;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
  text-shadow: 0 2px 24px rgba(0, 0, 0, 0.3);
}

.hero-description {
  font-size: clamp(1rem, 1.5vw, 1.05rem);
  color: rgba(255, 255, 255, 0.82);
  margin-bottom: 2.5rem;
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.2);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

/* ----------------------------------------------------------------
   PHILOSOPHY
---------------------------------------------------------------- */
.philosophy {
  background-color: var(--color-bg);
}

.philosophy-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.philosophy-item {
  padding: 2rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.philosophy-item:hover {
  border-color: var(--color-accent);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
}

@media (prefers-color-scheme: dark) {
  .philosophy-item:hover {
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
  }
}

.philosophy-icon {
  width: 40px;
  height: 40px;
  color: var(--color-accent);
  margin-bottom: 1.25rem;
}

.philosophy-icon svg {
  width: 100%;
  height: 100%;
}

.philosophy-item h3 {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.philosophy-item p {
  color: var(--color-text-muted);
}

/* ----------------------------------------------------------------
   SERVICES
---------------------------------------------------------------- */
.services {
  background-color: var(--color-surface-alt);
}

.services-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-bottom: 2.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--color-surface);
}

.service-item {
  display: flex;
  gap: 1.5rem;
  padding: 1.75rem 2rem;
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition);
}

.service-item:last-child {
  border-bottom: none;
}

.service-item:hover {
  background-color: var(--color-surface-alt);
}

.service-icon {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  color: var(--color-accent);
  margin-top: 0.15rem;
}

.service-icon svg {
  width: 100%;
  height: 100%;
}

.service-body h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.service-body p {
  font-size: 1rem;
  color: var(--color-text-muted);
  line-height: 1.85;
}

.services-note {
  text-align: center;
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-muted);
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  line-height: 2;
}

/* ----------------------------------------------------------------
   COMPANY
---------------------------------------------------------------- */
.company {
  background-color: var(--color-surface-alt);
}

.company-profile {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--color-surface);
  margin-bottom: 2rem;
}

.profile-row {
  display: flex;
  border-bottom: 1px solid var(--color-border-light);
}

.profile-row:last-child {
  border-bottom: none;
}

.company-profile dt {
  flex-shrink: 0;
  width: 120px;
  padding: 1.1rem 1.5rem;
  font-weight: 600;
  color: var(--color-text-subtle);
  background-color: var(--color-surface-alt);
  border-right: 1px solid var(--color-border-light);
  display: flex;
  align-items: center;
}

.company-profile dd {
  padding: 1.1rem 1.5rem;
  font-size: 1rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.25rem;
}

.company-profile dd a {
  color: var(--color-text);
}

.profile-en {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: 0.15rem;
}

/* ----------------------------------------------------------------
   CONTACT
---------------------------------------------------------------- */
.contact {
  background-color: var(--color-bg);
}

.contact-body {
  max-width: 600px;
  margin: 0 auto;
}

.contact-lead {
  font-size: 1.05rem;
  line-height: 2;
  color: var(--color-text);
  margin-bottom: 0.75rem;
}

.contact-note {
  font-size: 0.85rem;
}

/* ----------------------------------------------------------------
   SITE FOOTER
---------------------------------------------------------------- */
.site-footer {
  background-color: var(--color-surface-alt);
  border-top: 1px solid var(--color-border);
}

.site-footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 3rem 1.5rem 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  align-items: flex-start;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.footer-logo {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
  font-weight: 600;
  color: var(--color-text);
  font-family: var(--font-mono);
}

.footer-logo .logo-number {
  font-size: 1.4rem;
}

.footer-logo .logo-text {
  font-size: 0.88rem;
}

.footer-tagline {
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--color-text-subtle);
}

.footer-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.1rem 0.5rem;
}

.footer-nav a {
  display: block;
  padding: 0.2rem 0.4rem;
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  font-weight: 600;
  color: var(--color-text-muted);
  text-decoration: none;
}

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

.footer-copy {
  font-size: 0.75rem;
  color: var(--color-text-subtle);
}

/* ----------------------------------------------------------------
   RESPONSIVE — Tablet (< 900px)
---------------------------------------------------------------- */
@media (max-width: 900px) {
  .philosophy-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .philosophy-item {
    display: flex;
    gap: 1.25rem;
    align-items: flex-start;
    padding: 1.5rem;
  }

  .philosophy-icon {
    margin-bottom: 0;
    flex-shrink: 0;
  }

  .philosophy-content {
    flex: 1;
  }

  .company-profile dt {
    width: 100px;
    padding: 1rem 1rem;
  }

  .company-profile dd {
    padding: 1rem 1.25rem;
  }
}

/* ----------------------------------------------------------------
   RESPONSIVE — Mobile (< 640px)
---------------------------------------------------------------- */
@media (max-width: 640px) {
  :root {
    --section-padding: 4rem 1.25rem;
  }

  /* Header nav — mobile drawer */
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--color-header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-header-border);
    padding: 0.75rem 0;
  }

  .site-nav.is-open {
    display: block;
  }

  .site-nav ul {
    flex-direction: column;
    gap: 0;
  }

  .site-nav a {
    padding: 0.9rem 1.5rem;
    border-radius: 0;
    letter-spacing: 0.1em;
  }

  /* Hero */
  .hero-title {
    font-size: clamp(1.25rem, 6.5vw, 2.5rem);
  }

  .d-pc-none {
    display: block;
  }

  .hero-actions {
    flex-direction: column;
    align-items: flex-start;
  }

  .btn {
    text-align: center;
  }

  /* Services */
  .service-item {
    flex-direction: column;
    gap: 0.75rem;
    padding: 1.5rem;
  }

  /* Company */
  .profile-row {
    flex-direction: column;
  }

  .company-profile dt {
    width: 100%;
    padding: 0.6rem 1.25rem;
    border-right: none;
    border-bottom: 1px solid var(--color-border-light);
  }

  .company-profile dd {
    padding: 0.75rem 1.25rem 1rem;
  }

  /* Footer */
  .site-footer-inner {
    padding: 2.5rem 1.25rem 1.5rem;
  }
}

/* ----------------------------------------------------------------
   Reduced Motion
---------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  * {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}