/* =========================================
   ROTA+ Brand Site
   ========================================= */

:root {
  --color-bg: #fafaf8;
  --color-bg-alt: #ffffff;
  --color-text: #2a2a2a;
  --color-sub: #888888;
  --color-line: #ececea;

  /* Logo-derived gradient */
  --grad: linear-gradient(
    90deg,
    #6ab8e6 0%,
    #a07bd4 25%,
    #e87aa8 50%,
    #f0a866 75%,
    #8fcba1 100%
  );

  --max-width: 1200px;
  --font-en: "Jost", "Helvetica Neue", Arial, sans-serif;
  --font-jp: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
}

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

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

body {
  font-family: var(--font-jp);
  font-weight: 300;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.9;
  font-size: 15px;
  letter-spacing: 0.04em;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
  text-decoration: none;
  transition: opacity 0.3s ease;
}

a:hover {
  opacity: 0.6;
}

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 32px;
}

/* =========================================
   Header
   ========================================= */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: rgba(250, 250, 248, 0.85);
  z-index: 100;
}

.site-header::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 1px;
  background: var(--grad);
  opacity: 0.35;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 20px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: block;
}

.logo-img {
  height: 28px;
  width: auto;
  mix-blend-mode: multiply;
}

.global-nav ul {
  display: flex;
  gap: 40px;
}

.global-nav a {
  font-family: var(--font-en);
  font-size: 0.8rem;
  font-weight: 300;
  letter-spacing: 0.25em;
  text-transform: uppercase;
}

.nav-toggle {
  display: none;
  width: 32px;
  height: 32px;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  justify-content: space-between;
  padding: 10px 4px;
}

.nav-toggle span {
  display: block;
  height: 1px;
  background: var(--color-text);
}

/* =========================================
   Hero
   ========================================= */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg);
  padding: 120px 32px 80px;
  position: relative;
}

.hero-inner {
  text-align: center;
  max-width: 960px;
  width: 100%;
}

.hero-logo {
  width: 100%;
  max-width: 820px;
  height: auto;
  margin: 0 auto 48px;
  mix-blend-mode: multiply;
}

.hero-sub {
  font-size: 0.85rem;
  letter-spacing: 0.5em;
  margin-bottom: 20px;
  color: var(--color-sub);
  font-weight: 300;
}

.hero-lead {
  font-size: 1rem;
  letter-spacing: 0.3em;
  color: var(--color-text);
  font-weight: 300;
}

/* =========================================
   Section common
   ========================================= */
.section {
  padding: 140px 0;
  position: relative;
}

.section + .section::before {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 120px;
  height: 1px;
  background: var(--grad);
  opacity: 0.6;
}

.section-title {
  font-family: var(--font-en);
  font-size: 2rem;
  font-weight: 200;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  margin-bottom: 72px;
  text-align: center;
  position: relative;
}

.section-title .ja {
  display: block;
  font-family: var(--font-jp);
  font-size: 0.75rem;
  font-weight: 300;
  color: var(--color-sub);
  letter-spacing: 0.4em;
  margin-top: 16px;
}

/* =========================================
   Concept
   ========================================= */
.concept-body {
  max-width: 680px;
  margin: 0 auto;
  text-align: center;
}

.concept-body .lead {
  font-size: 1.3rem;
  font-weight: 300;
  margin-bottom: 40px;
  line-height: 1.8;
  letter-spacing: 0.15em;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.concept-body p + p {
  margin-top: 1.6em;
}

/* =========================================
   Story
   ========================================= */
.story .section-title {
  text-transform: none;
  font-style: italic;
  letter-spacing: 0.15em;
}

.story-body {
  max-width: 880px;
  margin: 0 auto;
}

.story-steps {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
}

.story-step {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 56px;
  align-items: start;
  position: relative;
  padding: 64px 0;
  border-top: 1px solid var(--color-line);
}

.story-step:first-child {
  border-top: none;
  padding-top: 8px;
}

.story-step:last-child {
  padding-bottom: 8px;
}

.step-head {
  display: flex;
  flex-direction: column;
  gap: 12px;
  position: sticky;
  top: 100px;
}

.step-num {
  font-family: var(--font-en);
  font-size: 3rem;
  font-weight: 200;
  letter-spacing: 0.05em;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1;
  display: block;
}

.step-label {
  font-family: var(--font-en);
  font-size: 0.75rem;
  font-weight: 300;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--color-sub);
}

.step-body {
  min-width: 0;
}

.step-title {
  font-size: 1.25rem;
  font-weight: 500;
  margin-bottom: 20px;
  letter-spacing: 0.12em;
  color: var(--color-text);
}

.step-lead {
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 20px;
  line-height: 1.8;
  letter-spacing: 0.08em;
}

.story-step .step-body p:not(.step-lead) {
  font-size: 0.9rem;
  color: var(--color-sub);
  line-height: 2;
  letter-spacing: 0.05em;
}

/* =========================================
   Material
   ========================================= */
.material-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 56px;
}

.material-card {
  text-align: center;
}

.material-thumb {
  aspect-ratio: 4 / 3;
  background: var(--color-bg-alt);
  margin-bottom: 28px;
  position: relative;
  overflow: hidden;
}

.material-thumb::after {
  content: "";
  position: absolute;
  inset: 0;
  border: 1px solid var(--color-line);
  pointer-events: none;
}

.material-card h3 {
  font-family: var(--font-en);
  font-size: 0.95rem;
  font-weight: 300;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.material-card p {
  font-size: 0.88rem;
  color: var(--color-sub);
  line-height: 1.9;
}

/* =========================================
   News
   ========================================= */
.news-list {
  max-width: 820px;
  margin: 0 auto;
}

.news-list li {
  display: grid;
  grid-template-columns: 140px 100px 1fr;
  align-items: center;
  gap: 32px;
  padding: 28px 8px;
  border-bottom: 1px solid var(--color-line);
}

.news-list li:first-child {
  border-top: 1px solid var(--color-line);
}

.news-list time {
  font-family: var(--font-en);
  font-weight: 300;
  letter-spacing: 0.08em;
  font-size: 0.9rem;
}

.news-cat {
  display: inline-block;
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  padding: 5px 14px;
  text-align: center;
  font-family: var(--font-en);
  font-weight: 300;
  text-transform: uppercase;
  color: var(--color-sub);
  border: 1px solid var(--color-line);
}

.news-list p {
  font-size: 0.9rem;
}

/* =========================================
   Contact
   ========================================= */
.contact {
  text-align: center;
}

.contact-lead {
  margin-bottom: 56px;
  color: var(--color-sub);
  font-size: 0.9rem;
  letter-spacing: 0.1em;
}

.contact-button {
  display: inline-block;
  padding: 22px 72px;
  font-family: var(--font-en);
  font-weight: 300;
  font-size: 0.85rem;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--color-text);
  background: transparent;
  position: relative;
  border: 1px solid transparent;
  background-image:
    linear-gradient(var(--color-bg), var(--color-bg)),
    var(--grad);
  background-origin: border-box;
  background-clip: padding-box, border-box;
  transition: color 0.4s ease, background 0.4s ease, opacity 0.3s;
}

.contact-button:hover {
  color: #ffffff;
  background-image:
    var(--grad),
    var(--grad);
  opacity: 1;
}

/* =========================================
   Footer
   ========================================= */
.site-footer {
  padding: 56px 0;
  text-align: center;
  position: relative;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 400px;
  height: 1px;
  background: var(--grad);
  opacity: 0.4;
}

.footer-logo {
  margin-bottom: 16px;
}

.footer-logo img {
  height: 24px;
  width: auto;
  margin: 0 auto;
  opacity: 0.9;
  mix-blend-mode: multiply;
}

.copyright {
  font-family: var(--font-en);
  font-size: 0.7rem;
  color: var(--color-sub);
  letter-spacing: 0.15em;
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 768px) {
  body {
    font-size: 14px;
  }

  .container {
    padding: 0 24px;
  }

  .global-nav {
    display: none;
  }

  .nav-toggle {
    display: flex;
  }

  .header-inner {
    padding: 16px 24px;
  }

  .logo-img {
    height: 20px;
  }

  .hero {
    min-height: 80vh;
    padding: 100px 24px 60px;
  }

  .hero-logo {
    max-width: 100%;
    margin-bottom: 32px;
  }

  .hero-sub {
    font-size: 0.75rem;
    letter-spacing: 0.4em;
  }

  .hero-lead {
    font-size: 0.85rem;
    letter-spacing: 0.2em;
  }

  .section {
    padding: 90px 0;
  }

  .section-title {
    font-size: 1.4rem;
    margin-bottom: 48px;
    letter-spacing: 0.25em;
  }

  .concept-body .lead {
    font-size: 1.05rem;
  }

  .material-grid {
    grid-template-columns: 1fr;
    gap: 56px;
  }

  .story .section-title {
    font-size: 1.25rem;
    letter-spacing: 0.1em;
  }

  .story-step {
    grid-template-columns: 1fr;
    gap: 20px;
    padding: 40px 0;
  }

  .step-head {
    position: static;
    flex-direction: row;
    align-items: baseline;
    gap: 16px;
  }

  .step-num {
    font-size: 2rem;
  }

  .step-label {
    font-size: 0.7rem;
    letter-spacing: 0.25em;
  }

  .step-title {
    font-size: 1.05rem;
    margin-bottom: 14px;
    letter-spacing: 0.08em;
  }

  .step-lead {
    font-size: 0.95rem;
    margin-bottom: 16px;
  }

  .story-step .step-body p:not(.step-lead) {
    font-size: 0.85rem;
  }

  .news-list li {
    grid-template-columns: 1fr;
    gap: 10px;
    padding: 22px 4px;
  }

  .news-cat {
    justify-self: start;
  }

  .contact-button {
    padding: 20px 48px;
    width: 100%;
    max-width: 320px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 20px;
  }

  .header-inner {
    padding: 14px 20px;
  }

  .logo-img {
    height: 18px;
  }
}