/* ========================================
   Brand Square - Column Site
   Design System & Styles
   ======================================== */

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

:root {
  /* Colors */
  --color-bg: #ffffff;
  --color-bg-subtle: #f8f8f7;
  --color-bg-card: #ffffff;
  --color-text: #2d2d2d;
  --color-text-light: #6b6b6b;
  --color-text-muted: #999999;
  --color-accent: #3a3a3a;
  --color-accent-hover: #1a1a1a;
  --color-border: #e8e8e6;
  --color-border-light: #f0f0ee;
  --color-highlight: #c9a96e;
  --color-highlight-light: rgba(201, 169, 110, 0.08);

  /* Typography */
  --font-body: 'Noto Sans JP', 'Hiragino Kaku Gothic ProN', 'Yu Gothic', sans-serif;
  --font-heading: 'Noto Serif JP', 'Hiragino Mincho ProN', 'Yu Mincho', serif;
  --font-accent: 'Cormorant Garamond', 'Noto Serif JP', serif;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;

  /* Sizing */
  --max-width: 1100px;
  --max-width-article: 740px;

  /* Transitions */
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.9;
  letter-spacing: 0.02em;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}


/* --- Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border-light);
  transition: box-shadow var(--transition-base);
}

.site-header.scrolled {
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.04);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.2rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  text-decoration: none;
  display: flex;
  align-items: baseline;
  gap: 0.3rem;
}

.site-logo-text {
  font-family: var(--font-accent);
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--color-text);
  letter-spacing: 0.04em;
}

.site-logo-dot {
  color: var(--color-highlight);
  font-size: 1.8rem;
  line-height: 1;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.header-nav a {
  text-decoration: none;
  color: var(--color-text-light);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
  transition: color var(--transition-fast);
  position: relative;
}

.header-nav a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-highlight);
  transition: width var(--transition-base);
}

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

.header-nav a:hover::after {
  width: 100%;
}


/* --- Hero (Index Page) --- */
.hero {
  padding: var(--space-2xl) 2rem;
  text-align: center;
  background: var(--color-bg);
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 1px;
  height: 60px;
  background: linear-gradient(to bottom, transparent, var(--color-border));
}

.hero-label {
  font-family: var(--font-accent);
  font-size: 0.8rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-highlight);
  margin-bottom: var(--space-md);
  display: inline-block;
  padding-top: 80px;
}

.hero h1 {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.6;
  margin-bottom: var(--space-md);
  letter-spacing: 0.04em;
}

.hero-description {
  font-size: 0.95rem;
  color: var(--color-text-light);
  max-width: 560px;
  margin: 0 auto;
  line-height: 2;
}


/* --- Column List --- */
.column-list-section {
  padding: var(--space-xl) 2rem var(--space-2xl);
  max-width: var(--max-width);
  margin: 0 auto;
  width: 100%;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: var(--space-xl);
}

.section-header-line {
  flex: 1;
  height: 1px;
  background: var(--color-border);
}

.section-header-label {
  font-family: var(--font-accent);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  white-space: nowrap;
}

.column-list {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--color-border-light);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.column-item {
  display: grid;
  grid-template-columns: 80px 1fr auto;
  align-items: center;
  gap: var(--space-lg);
  padding: var(--space-lg) var(--space-md);
  background: var(--color-bg);
  text-decoration: none;
  color: inherit;
  transition: background var(--transition-fast), padding-left var(--transition-base);
  position: relative;
}

.column-item:hover {
  background: var(--color-highlight-light);
  padding-left: calc(var(--space-md) + 8px);
}

.column-number {
  font-family: var(--font-accent);
  font-size: 2.2rem;
  font-weight: 300;
  color: var(--color-border);
  line-height: 1;
  transition: color var(--transition-base);
  text-align: center;
}

.column-item:hover .column-number {
  color: var(--color-highlight);
}

.column-content {
  min-width: 0;
}

.column-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.6;
  margin-bottom: 0.4rem;
  transition: color var(--transition-fast);
}

.column-item:hover .column-title {
  color: var(--color-accent-hover);
}

.column-excerpt {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.column-arrow {
  font-size: 1.2rem;
  color: var(--color-border);
  transition: color var(--transition-fast), transform var(--transition-base);
  flex-shrink: 0;
}

.column-item:hover .column-arrow {
  color: var(--color-highlight);
  transform: translateX(4px);
}


/* --- Article Page --- */
.article-header {
  padding: var(--space-2xl) 2rem var(--space-xl);
  text-align: center;
  max-width: var(--max-width-article);
  margin: 0 auto;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-bottom: var(--space-lg);
}

.article-number {
  font-family: var(--font-accent);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-highlight);
  background: var(--color-highlight-light);
  padding: 0.3rem 1rem;
  border-radius: 2px;
}

.article-header h1 {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.7;
  letter-spacing: 0.03em;
}

.article-header-divider {
  width: 40px;
  height: 1px;
  background: var(--color-highlight);
  margin: var(--space-lg) auto 0;
}


/* --- Article Body --- */
.article-body {
  max-width: var(--max-width-article);
  margin: 0 auto;
  padding: 0 2rem var(--space-2xl);
}

.article-body p {
  margin-bottom: 1.8rem;
  font-size: 1rem;
  line-height: 2.1;
  color: var(--color-text);
}

.article-body .emphasis-line {
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--color-accent);
  padding-left: 1.2rem;
  border-left: 2px solid var(--color-highlight);
  margin: 2.5rem 0;
  line-height: 2;
}

.article-body .bullet-list {
  margin: 1.5rem 0 2rem;
  padding: 0;
  list-style: none;
}

.article-body .bullet-list li {
  position: relative;
  padding-left: 1.4rem;
  margin-bottom: 0.6rem;
  font-size: 0.95rem;
  line-height: 1.9;
  color: var(--color-text);
}

.article-body .bullet-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.85rem;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--color-highlight);
}

.article-body .section-break {
  text-align: center;
  margin: 3rem 0;
  color: var(--color-border);
  font-size: 0.9rem;
  letter-spacing: 1em;
}


/* --- Callout Box (引用・補足ボックス) --- */
.article-body .callout-box {
  background: linear-gradient(135deg, var(--color-highlight-light), rgba(201, 169, 110, 0.03));
  border-left: 3px solid var(--color-highlight);
  border-radius: 0 6px 6px 0;
  padding: 1.8rem 2rem;
  margin: 2.5rem 0;
  position: relative;
}

.article-body .callout-box::before {
  content: '✦';
  position: absolute;
  top: -10px;
  left: -12px;
  width: 24px;
  height: 24px;
  background: var(--color-highlight);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.65rem;
}

.article-body .callout-box p {
  margin-bottom: 0;
  font-size: 0.95rem;
  line-height: 2;
  color: var(--color-text);
}


/* --- Case List (業種別事例カード) --- */
.article-body .case-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin: 2rem 0 2.5rem;
}

.article-body .case-item {
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border-light);
  border-radius: 8px;
  padding: 1.5rem 1.8rem;
  position: relative;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.article-body .case-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.04);
}

.article-body .case-label {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-highlight);
  background: rgba(201, 169, 110, 0.12);
  padding: 0.2rem 0.8rem;
  border-radius: 3px;
  margin-bottom: 0.8rem;
  letter-spacing: 0.06em;
}

.article-body .case-item p {
  margin-bottom: 0;
  font-size: 0.93rem;
  line-height: 1.9;
}


/* --- Bullet List Variants (リストバリエーション) --- */
.article-body .bullet-list.accent li::before {
  background: var(--color-highlight);
  width: 6px;
  height: 6px;
}

.article-body .bullet-list.warning li::before {
  background: #c97a6e;
  border-radius: 1px;
  transform: rotate(45deg);
  width: 6px;
  height: 6px;
}

.article-body .bullet-list.scenario li {
  padding-left: 1.6rem;
  margin-bottom: 0.8rem;
  font-size: 0.95rem;
}

.article-body .bullet-list.scenario li::before {
  background: none;
  border: 2px solid var(--color-highlight);
  width: 7px;
  height: 7px;
  top: 0.75rem;
}


/* --- Closing Emphasis (締めの強調) --- */
.article-body .emphasis-line.closing {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text);
  background: linear-gradient(135deg, var(--color-highlight-light), transparent);
  padding: 1.5rem 1.5rem 1.5rem 1.5rem;
  border-left: 3px solid var(--color-highlight);
  border-radius: 0 6px 6px 0;
  margin: 3rem 0 2rem;
  line-height: 2;
}


/* --- Continue Mark (「続く」マーク) --- */
.article-body .continue-mark {
  display: block;
  text-align: center;
  font-family: var(--font-heading);
  font-size: 0.95rem;
  color: var(--color-text-muted);
  letter-spacing: 0.3em;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border-light);
  text-decoration: none;
  transition: color var(--transition-fast), letter-spacing var(--transition-base);
}

.article-body .continue-mark:hover {
  color: var(--color-highlight);
  letter-spacing: 0.5em;
}


/* --- Article Navigation --- */
.article-nav {
  max-width: var(--max-width-article);
  margin: 0 auto;
  padding: 0 2rem var(--space-xl);
}

.article-nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: stretch;
  gap: var(--space-md);
  border-top: 1px solid var(--color-border);
  padding-top: var(--space-lg);
}

.article-nav-link {
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  padding: var(--space-sm);
  border-radius: 4px;
  transition: background var(--transition-fast);
  max-width: 45%;
}

.article-nav-link:hover {
  background: var(--color-bg-subtle);
}

.article-nav-link.next {
  text-align: right;
  margin-left: auto;
}

.article-nav-label {
  font-size: 0.7rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.article-nav-title {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  color: var(--color-text);
  line-height: 1.5;
}

.back-to-list {
  display: block;
  text-align: center;
  margin: 0 auto var(--space-2xl);
  padding: 0.8rem 2rem;
  text-decoration: none;
  color: var(--color-text-light);
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  border: 1px solid var(--color-border);
  border-radius: 2px;
  transition: all var(--transition-fast);
  width: fit-content;
}

.back-to-list:hover {
  color: var(--color-text);
  border-color: var(--color-text-muted);
  background: var(--color-bg-subtle);
}


/* --- Contact Section --- */
.contact-section {
  background: var(--color-bg-subtle);
  padding: var(--space-2xl) 2rem;
  border-top: 1px solid var(--color-border-light);
}

.contact-inner {
  max-width: 680px;
  margin: 0 auto;
  text-align: center;
}

.contact-label {
  font-family: var(--font-accent);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-highlight);
  margin-bottom: var(--space-sm);
}

.contact-heading {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
  line-height: 1.6;
}

.contact-description {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: var(--space-xl);
  line-height: 1.9;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  text-align: left;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.8rem;
  color: var(--color-text-light);
  letter-spacing: 0.05em;
}

.form-group input,
.form-group textarea {
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.9rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 3px;
  background: var(--color-bg);
  color: var(--color-text);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  outline: none;
  letter-spacing: 0.02em;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-highlight);
  box-shadow: 0 0 0 3px var(--color-highlight-light);
}

.form-group textarea {
  resize: vertical;
  min-height: 140px;
  line-height: 1.8;
}

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

.submit-btn {
  font-family: var(--font-body);
  font-size: 0.9rem;
  letter-spacing: 0.1em;
  padding: 1rem 2rem;
  background: var(--color-accent);
  color: #ffffff;
  border: none;
  border-radius: 3px;
  cursor: pointer;
  transition: background var(--transition-fast), transform var(--transition-fast);
  margin-top: var(--space-sm);
}

.submit-btn:hover {
  background: var(--color-accent-hover);
  transform: translateY(-1px);
}

.submit-btn:active {
  transform: translateY(0);
}

.contact-alt {
  margin-top: var(--space-xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  flex-wrap: wrap;
}

.contact-alt-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--color-text-light);
  font-size: 0.85rem;
  text-decoration: none;
  transition: color var(--transition-fast);
}

.contact-alt-item:hover {
  color: var(--color-text);
}

.contact-alt-icon {
  width: 36px;
  height: 36px;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}

.contact-alt-item:hover .contact-alt-icon {
  border-color: var(--color-highlight);
  background: var(--color-highlight-light);
}


/* --- Footer --- */
.site-footer {
  margin-top: auto;
  padding: var(--space-lg) 2rem;
  text-align: center;
  border-top: 1px solid var(--color-border-light);
  background: var(--color-bg);
}

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


/* --- Fade-in Animation --- */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

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


/* --- Responsive --- */
@media (max-width: 768px) {
  :root {
    --space-xl: 3rem;
    --space-2xl: 4rem;
  }

  .header-inner {
    padding: 1rem 1.2rem;
  }

  .site-logo-text {
    font-size: 1.25rem;
  }

  .header-nav {
    gap: 1.2rem;
  }

  .header-nav a {
    font-size: 0.78rem;
  }

  .hero {
    padding: var(--space-xl) 1.2rem;
  }

  .hero h1 {
    font-size: 1.5rem;
  }

  .hero-label {
    padding-top: 50px;
  }

  .hero::before {
    height: 40px;
  }

  .column-list-section {
    padding: var(--space-lg) 1.2rem var(--space-xl);
  }

  .column-item {
    grid-template-columns: 50px 1fr auto;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-sm);
  }

  .column-item:hover {
    padding-left: calc(var(--space-sm) + 4px);
  }

  .column-number {
    font-size: 1.6rem;
  }

  .column-title {
    font-size: 1rem;
  }

  .column-excerpt {
    display: none;
  }

  .article-header {
    padding: var(--space-xl) 1.2rem var(--space-lg);
  }

  .article-header h1 {
    font-size: 1.35rem;
  }

  .article-body {
    padding: 0 1.2rem var(--space-xl);
  }

  .article-nav {
    padding: 0 1.2rem var(--space-lg);
  }

  .article-nav-inner {
    flex-direction: column;
    gap: var(--space-sm);
  }

  .article-nav-link {
    max-width: 100%;
  }

  .article-nav-link.next {
    text-align: left;
  }

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

  .contact-section {
    padding: var(--space-xl) 1.2rem;
  }

  .contact-heading {
    font-size: 1.25rem;
  }

  .contact-alt {
    flex-direction: column;
    align-items: center;
    gap: var(--space-md);
  }

  .article-body .callout-box {
    padding: 1.4rem 1.2rem;
    margin: 2rem 0;
  }

  .article-body .case-item {
    padding: 1.2rem 1.4rem;
  }

  .article-body .emphasis-line.closing {
    font-size: 1.05rem;
    padding: 1.2rem;
  }

  .article-body .case-label {
    font-size: 0.75rem;
  }
}

@media (max-width: 480px) {
  .header-nav {
    display: none;
  }

  .column-item {
    grid-template-columns: 40px 1fr;
  }

  .column-arrow {
    display: none;
  }

  .article-header h1 {
    font-size: 1.2rem;
  }
}