/* ============================================
   syusai - Corporate Site
   Design: Achromatic, Minimal, Refined
   ============================================ */

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

:root {
  /* Colors */
  --sumi: #1a1a1a;
  --tetsu: #17202a;
  --hai: #9ea1a3;
  --hai-light: #c8c9ca;
  --shiro: #e8e6e1;
  --shiro-pure: #f5f4f0;
  --bg-dark: #111111;
  --bg-section: #0d0d0d;

  /* Typography */
  --font-primary: "Noto Sans JP", "Helvetica Neue", Arial, sans-serif;
  --font-en: "Inter", "Helvetica Neue", Arial, sans-serif;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 2rem;
  --space-lg: 4rem;
  --space-xl: 8rem;
  --space-2xl: 12rem;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --duration: 0.6s;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-primary);
  background-color: var(--bg-dark);
  color: var(--shiro);
  line-height: 1.8;
  letter-spacing: 0.04em;
  overflow-x: hidden;
}

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

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

/* --- Utility --- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.container--narrow {
  max-width: 800px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* --- Fade-in Animation --- */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--duration) var(--ease-out),
              transform var(--duration) var(--ease-out);
}

.fade-in.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Noise Texture Overlay --- */
body::before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.03;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 9999;
}

/* ============================================
   Header
   ============================================ */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  padding: var(--space-md) 0;
  transition: background-color 0.4s ease, padding 0.4s ease;
}

.header.is-scrolled {
  background-color: rgba(17, 17, 17, 0.95);
  backdrop-filter: blur(12px);
  padding: var(--space-sm) 0;
}

.header__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header__logo {
  font-family: var(--font-en);
  font-size: 1.25rem;
  font-weight: 300;
  letter-spacing: 0.2em;
  text-transform: lowercase;
  color: var(--shiro);
}

.header__nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.header__nav-link {
  font-family: var(--font-en);
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--hai);
  transition: color 0.3s ease;
  position: relative;
}

.header__nav-link::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--shiro);
  transition: width 0.4s var(--ease-out);
}

.header__nav-link:hover {
  color: var(--shiro);
}

.header__nav-link:hover::after {
  width: 100%;
}

/* Mobile Menu */
.header__menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  width: 32px;
  height: 24px;
  position: relative;
  z-index: 1001;
}

.header__menu-btn span {
  display: block;
  width: 100%;
  height: 1px;
  background-color: var(--shiro);
  position: absolute;
  left: 0;
  transition: all 0.3s ease;
}

.header__menu-btn span:nth-child(1) { top: 0; }
.header__menu-btn span:nth-child(2) { top: 50%; }
.header__menu-btn span:nth-child(3) { bottom: 0; }

.header__menu-btn.is-active span:nth-child(1) {
  top: 50%;
  transform: rotate(45deg);
}
.header__menu-btn.is-active span:nth-child(2) {
  opacity: 0;
}
.header__menu-btn.is-active span:nth-child(3) {
  bottom: 50%;
  transform: rotate(-45deg);
}

/* ============================================
   Hero
   ============================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.hero__content {
  text-align: center;
  position: relative;
  z-index: 1;
}

.hero__logo-text {
  font-family: var(--font-en);
  font-size: clamp(3rem, 8vw, 7rem);
  font-weight: 200;
  letter-spacing: 0.3em;
  text-transform: lowercase;
  color: var(--shiro);
  margin-bottom: var(--space-md);
  opacity: 0;
  animation: heroFadeIn 1.5s var(--ease-out) 0.3s forwards;
}

.hero__tagline {
  font-size: 0.85rem;
  font-weight: 300;
  letter-spacing: 0.25em;
  color: var(--hai);
  opacity: 0;
  animation: heroFadeIn 1.5s var(--ease-out) 0.8s forwards;
}

.hero__line {
  width: 1px;
  height: 80px;
  background-color: var(--hai);
  margin: var(--space-lg) auto 0;
  opacity: 0;
  animation: heroLineIn 1.5s var(--ease-out) 1.2s forwards;
}

@keyframes heroFadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes heroLineIn {
  from {
    opacity: 0;
    height: 0;
  }
  to {
    opacity: 0.5;
    height: 80px;
  }
}

/* Subtle gradient background */
.hero__bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(ellipse at 30% 50%, rgba(23, 32, 42, 0.4) 0%, transparent 60%),
              radial-gradient(ellipse at 70% 50%, rgba(26, 26, 26, 0.3) 0%, transparent 60%);
}

/* ============================================
   Section Common
   ============================================ */
.section {
  padding: var(--space-2xl) 0;
}

.section--alt {
  background-color: var(--bg-section);
}

.section__label {
  font-family: var(--font-en);
  font-size: 0.7rem;
  font-weight: 400;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--hai);
  margin-bottom: var(--space-xs);
}

.section__title {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 300;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-lg);
  line-height: 1.4;
}

.section__divider {
  width: 40px;
  height: 1px;
  background-color: var(--hai);
  margin-bottom: var(--space-lg);
  opacity: 0.5;
}

/* ============================================
   Service - 事業紹介
   ============================================ */
.service-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

.service-card {
  border: 1px solid rgba(158, 161, 163, 0.15);
  padding: var(--space-lg);
  transition: border-color 0.4s ease, background-color 0.4s ease;
  position: relative;
  overflow: hidden;
}

.service-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(158, 161, 163, 0.03) 0%, transparent 50%);
  opacity: 0;
  transition: opacity 0.4s ease;
}

.service-card:hover {
  border-color: rgba(158, 161, 163, 0.35);
}

.service-card:hover::before {
  opacity: 1;
}

.service-card__number {
  font-family: var(--font-en);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  color: var(--hai);
  margin-bottom: var(--space-md);
}

.service-card__title {
  font-size: 1.5rem;
  font-weight: 300;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-sm);
}

.service-card__subtitle {
  font-family: var(--font-en);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--hai);
  margin-bottom: var(--space-md);
}

.service-card__desc {
  font-size: 0.875rem;
  color: var(--hai-light);
  line-height: 2;
  margin-bottom: var(--space-md);
}

.service-card__link {
  font-family: var(--font-en);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--hai);
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  transition: color 0.3s ease;
}

.service-card__link::after {
  content: "→";
  transition: transform 0.3s var(--ease-out);
}

.service-card__link:hover {
  color: var(--shiro);
}

.service-card__link:hover::after {
  transform: translateX(4px);
}

/* ============================================
   Sub Services (Web制作 details)
   ============================================ */
.sub-services {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  margin-top: var(--space-lg);
}

.sub-service {
  padding: var(--space-md);
  border-top: 1px solid rgba(158, 161, 163, 0.15);
  transition: border-color 0.3s ease;
}

.sub-service:hover {
  border-color: rgba(158, 161, 163, 0.4);
}

.sub-service__title {
  font-size: 1rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  margin-bottom: var(--space-xs);
}

.sub-service__en {
  font-family: var(--font-en);
  font-size: 0.65rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--hai);
  margin-bottom: var(--space-sm);
}

.sub-service__desc {
  font-size: 0.8rem;
  color: var(--hai-light);
  line-height: 1.9;
}

/* ============================================
   Works - 実績紹介
   ============================================ */
.works-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2px;
  margin-top: var(--space-lg);
}

.work-item {
  aspect-ratio: 4 / 3;
  background-color: var(--sumi);
  position: relative;
  overflow: hidden;
  cursor: pointer;
}

.work-item__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.6s var(--ease-out), opacity 0.6s ease;
}

.work-item__overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  padding: var(--space-md);
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
  transform: translateY(100%);
  transition: transform 0.4s var(--ease-out);
}

.work-item:hover .work-item__img {
  transform: scale(1.05);
  opacity: 0.7;
}

.work-item:hover .work-item__overlay {
  transform: translateY(0);
}

.work-item__title {
  font-size: 0.875rem;
  font-weight: 400;
  letter-spacing: 0.06em;
}

.work-item__category {
  font-family: var(--font-en);
  font-size: 0.65rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--hai);
  margin-top: var(--space-xs);
}

/* ============================================
   About - 会社概要
   ============================================ */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-xl);
  align-items: start;
  margin-top: var(--space-lg);
}

.about__message {
  font-size: 1.125rem;
  font-weight: 300;
  line-height: 2.2;
  letter-spacing: 0.06em;
  margin-bottom: var(--space-md);
}

.about__text {
  font-size: 0.875rem;
  color: var(--hai-light);
  line-height: 2;
}

.about-info {
  border-top: 1px solid rgba(158, 161, 163, 0.15);
}

.about-info__row {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: var(--space-md);
  padding: var(--space-sm) 0;
  border-bottom: 1px solid rgba(158, 161, 163, 0.08);
  font-size: 0.85rem;
}

.about-info__label {
  color: var(--hai);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
}

.about-info__value {
  color: var(--hai-light);
}

/* ============================================
   News / Blog
   ============================================ */
.news-list {
  margin-top: var(--space-lg);
}

.news-item {
  display: grid;
  grid-template-columns: 120px auto 1fr;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-bottom: 1px solid rgba(158, 161, 163, 0.1);
  align-items: baseline;
  transition: background-color 0.3s ease;
}

.news-item:hover {
  background-color: rgba(158, 161, 163, 0.03);
}

.news-item__date {
  font-family: var(--font-en);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--hai);
}

.news-item__tag {
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  color: var(--hai);
  border: 1px solid rgba(158, 161, 163, 0.3);
  padding: 0.15em 0.8em;
  display: inline-block;
}

.news-item__title {
  font-size: 0.875rem;
  font-weight: 400;
  transition: color 0.3s ease;
}

.news-item:hover .news-item__title {
  color: var(--shiro);
}

/* ============================================
   Contact
   ============================================ */
.contact {
  text-align: center;
  padding: var(--space-2xl) 0;
}

.contact__heading {
  font-family: var(--font-en);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 200;
  letter-spacing: 0.2em;
  text-transform: lowercase;
  margin-bottom: var(--space-md);
}

.contact__text {
  font-size: 0.875rem;
  color: var(--hai-light);
  margin-bottom: var(--space-lg);
  line-height: 2;
}

.contact__btn {
  display: inline-block;
  font-family: var(--font-en);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--shiro);
  border: 1px solid rgba(158, 161, 163, 0.4);
  padding: 1.2em 3.5em;
  transition: all 0.4s var(--ease-out);
}

.contact__btn:hover {
  background-color: var(--shiro);
  color: var(--bg-dark);
  border-color: var(--shiro);
}

/* ============================================
   Footer
   ============================================ */
.footer {
  border-top: 1px solid rgba(158, 161, 163, 0.1);
  padding: var(--space-lg) 0;
}

.footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer__logo {
  font-family: var(--font-en);
  font-size: 0.9rem;
  font-weight: 300;
  letter-spacing: 0.2em;
  text-transform: lowercase;
}

.footer__nav {
  display: flex;
  gap: var(--space-md);
}

.footer__nav-link {
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: var(--hai);
  transition: color 0.3s ease;
}

.footer__nav-link:hover {
  color: var(--shiro);
}

.footer__copy {
  font-family: var(--font-en);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  color: var(--hai);
  text-align: center;
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid rgba(158, 161, 163, 0.06);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
  .header__nav {
    display: none;
  }

  .header__menu-btn {
    display: block;
  }

  .header__nav.is-open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background-color: var(--bg-dark);
    justify-content: center;
    align-items: center;
    gap: var(--space-lg);
    z-index: 1000;
  }

  .header__nav.is-open .header__nav-link {
    font-size: 1rem;
  }

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

  .sub-services {
    grid-template-columns: 1fr;
  }

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

  .about-grid {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }

  .news-item {
    grid-template-columns: 1fr;
    gap: var(--space-xs);
  }

  .footer__inner {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .footer__nav {
    flex-wrap: wrap;
    justify-content: center;
  }
}