/* ============================================================
   100 Excel - はじめての方に（welcome）
   ============================================================ */

:root {
  /* Base palette */
  --excel-green:    #1d6f42;
  --excel-green-l:  #2f8456;
  --excel-green-d:  #155a35;
  --excel-green-ll: #4a9d6d;
  --excel-green-soft: rgba(29, 111, 66, 0.08);
  --ink:        #1a1a1a;
  --ink-soft:   #555;
  --ink-mute:   #999;
  --line:       #e8e8e8;
  --paper:      #ffffff;
  --cream:      #f8f8f5;

  /* Typography */
  --font-jp:        "Zen Maru Gothic", "Noto Sans JP", -apple-system, sans-serif;
  --font-mono:      "DM Mono", "JetBrains Mono", "Roboto Mono", monospace;
  --font-body:      "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

html, body {
  width: 100%;
  min-height: 100vh;
  background: var(--cream);
  color: var(--ink);
  font-family: var(--font-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: none; background: none; }

/* ============================================================
   列ヘッダー（A〜I の Excel風）
   ============================================================ */
.col-headers-top {
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  height: 26px;
  background: #f3f3f3;
  border-bottom: 1px solid #d4d4d4;
  display: flex;
  font-family: var(--font-mono);
  font-size: 10px;
  color: #595959;
  z-index: 100;
  letter-spacing: 0.05em;
}
.col-headers-top span {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border-right: 1px solid #d4d4d4;
}
.col-headers-top span:last-child { border-right: none; }

[data-time="night"] .col-headers-top {
  background: #0e1626;
  color: #8b95a8;
  border-bottom: none;
  box-shadow: none;
}
[data-time="night"] .col-headers-top span {
  border-right-color: rgba(255, 255, 255, 0.06);
  opacity: 0.7;
}

/* ============================================================
   サイトヘッダー
   ============================================================ */
.site-header {
  position: sticky;
  top: 26px;
  left: 0; right: 0;
  background: var(--paper);
  border-bottom: 1px solid var(--line);
  padding: 14px 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 99;
}
.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: 0.15em;
}
.brand-dot {
  width: 8px; height: 8px;
  background: var(--excel-green);
  border-radius: 50%;
}
.top-nav {
  display: flex;
  align-items: center;
  gap: 24px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.15em;
}
.top-nav a {
  color: var(--ink-soft);
  transition: color 0.2s ease;
}
.top-nav a:hover { color: var(--excel-green); }

/* ============================================================
   テーマ切替トグル
   ============================================================ */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 100px;
  padding: 3px;
  margin-left: 8px;
}
.theme-toggle-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  color: var(--ink-mute);
  cursor: pointer;
  transition: all 0.2s ease;
  padding: 0;
}
.theme-toggle-btn:hover {
  color: var(--ink-soft);
  background: var(--cream);
}
.theme-toggle-btn.is-active {
  background: var(--excel-green);
  color: var(--paper);
}
.theme-toggle-btn svg { width: 14px; height: 14px; }

/* ============================================================
   メイン
   ============================================================ */
.main {
  max-width: 880px;
  margin: 0 auto;
  padding: 40px 32px 80px;
}

/* パンくず */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-mute);
  letter-spacing: 0.08em;
  margin-bottom: 32px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.breadcrumb a {
  color: var(--ink-soft);
  transition: color 0.2s ease;
}
.breadcrumb a:hover { color: var(--excel-green); }
.bc-sep { color: var(--ink-mute); opacity: 0.5; }
.bc-current { color: var(--ink); }

/* ============================================================
   ヒーロー
   ============================================================ */
.welcome-hero {
  text-align: center;
  margin-bottom: 56px;
  padding-bottom: 48px;
  border-bottom: 1px solid var(--line);
}
.welcome-kicker {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.32em;
  color: var(--excel-green);
  margin-bottom: 14px;
}
.welcome-title {
  font-family: var(--font-jp);
  font-size: clamp(2rem, 5vw, 2.8rem);
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 18px;
  letter-spacing: 0.04em;
}
.welcome-subtitle {
  font-family: var(--font-body);
  font-size: 1rem;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
}

/* ============================================================
   セクション共通
   ============================================================ */
.welcome-section-title {
  font-family: var(--font-jp);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 28px;
  padding-bottom: 14px;
  border-bottom: 2px solid var(--excel-green);
  letter-spacing: 0.04em;
}

/* ============================================================
   ご挨拶
   ============================================================ */
.welcome-greeting {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 40px 44px;
  margin-bottom: 56px;
}
.welcome-greeting-body p {
  font-family: var(--font-body);
  font-size: 0.98rem;
  line-height: 1.9;
  color: var(--ink);
  margin-bottom: 18px;
}
.welcome-greeting-body p:last-child { margin-bottom: 0; }
.welcome-greeting-body strong {
  color: var(--excel-green-d);
  font-weight: 700;
}

/* ============================================================
   学習のすすめ方（4カード）
   ============================================================ */
.welcome-howto {
  margin-bottom: 56px;
}
.howto-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.howto-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 28px 26px;
  transition: all 0.25s ease;
}
.howto-card:hover {
  border-color: var(--excel-green);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(29, 111, 66, 0.08);
}
.howto-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: var(--excel-green-soft);
  color: var(--excel-green);
  margin-bottom: 18px;
}
.howto-title {
  font-family: var(--font-jp);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 12px;
  letter-spacing: 0.03em;
}
.howto-text {
  font-family: var(--font-body);
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--ink-soft);
}
.howto-text a {
  color: var(--excel-green);
  font-weight: 500;
  border-bottom: 1px solid currentColor;
  transition: color 0.2s ease;
}
.howto-text a:hover {
  color: var(--excel-green-d);
}
.howto-text strong {
  color: var(--excel-green-d);
  font-weight: 700;
}

/* ============================================================
   CTA
   ============================================================ */
.welcome-cta {
  text-align: center;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 44px 32px;
}
.welcome-cta-text {
  font-family: var(--font-jp);
  font-size: 1.05rem;
  color: var(--ink);
  margin-bottom: 28px;
  letter-spacing: 0.03em;
}
.welcome-cta-buttons {
  display: inline-flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
}
.welcome-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 32px;
  font-family: var(--font-jp);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  border-radius: 100px;
  transition: all 0.25s ease;
}
.welcome-btn-primary {
  background: var(--excel-green);
  color: var(--paper);
  box-shadow: 0 3px 0 var(--excel-green-d);
}
.welcome-btn-primary:hover {
  background: var(--excel-green-d);
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(29, 111, 66, 0.3);
}
.welcome-btn-secondary {
  background: var(--paper);
  color: var(--excel-green);
  border: 1.5px solid var(--excel-green);
}
.welcome-btn-secondary:hover {
  background: var(--excel-green-soft);
}

/* ============================================================
   フッター（ダークグレー #1a1a1a）
   ============================================================ */
.site-footer {
  background: #1a1a1a;
  border-top: 1px solid #2a2a2a;
  padding: 32px 0 24px;
  font-family: var(--font-jp);
  color: #d0d0d0;
}
.site-footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px;
}
.site-footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 20px;
  margin-bottom: 18px;
  border-bottom: 1px solid #2e2e2e;
  gap: 20px;
  flex-wrap: wrap;
}
.footer-brand {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
  color: #e8e8e8;
}
.footer-logo-img {
  height: 32px;
  width: auto;
  display: inline-block;
}
.footer-logo-text {
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.18em;
  color: #e8e8e8;
  font-weight: 500;
}
.footer-brand-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #21a366;
}
.footer-nav {
  display: flex;
  gap: 24px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.15em;
  flex-wrap: wrap;
}
.footer-nav a {
  color: #a0a0a0;
  text-decoration: none;
  transition: color 0.2s ease;
}
.footer-nav a:hover {
  color: #21a366;
}
.site-footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-jp);
  font-size: 0.78rem;
  color: #888;
  gap: 16px;
  flex-wrap: wrap;
}

/* ============================================================
   レスポンシブ
   ============================================================ */
@media (max-width: 767px) {
  .site-header {
    padding: 12px 16px;
    flex-direction: column;
    gap: 10px;
    align-items: flex-start;
  }
  .top-nav { gap: 14px; font-size: 10px; flex-wrap: wrap; }
  .theme-toggle { margin-left: 0; margin-top: 4px; }
  .theme-toggle-btn { width: 26px; height: 26px; }
  .theme-toggle-btn svg { width: 12px; height: 12px; }

  .main { padding: 24px 16px 48px; }

  .welcome-hero {
    margin-bottom: 36px;
    padding-bottom: 32px;
  }
  .welcome-subtitle { font-size: 0.9rem; }

  .welcome-greeting {
    padding: 24px 20px;
    margin-bottom: 36px;
  }
  .welcome-greeting-body p {
    font-size: 0.92rem;
    line-height: 1.85;
  }

  .welcome-howto { margin-bottom: 36px; }
  .howto-grid {
    grid-template-columns: 1fr;
    gap: 14px;
  }
  .howto-card { padding: 22px 20px; }
  .howto-icon {
    width: 44px;
    height: 44px;
    margin-bottom: 14px;
  }
  .howto-icon svg { width: 26px; height: 26px; }
  .howto-title { font-size: 1.02rem; margin-bottom: 10px; }
  .howto-text { font-size: 0.85rem; line-height: 1.75; }

  .welcome-section-title {
    font-size: 1.2rem;
    margin-bottom: 22px;
  }

  .welcome-cta {
    padding: 32px 20px;
  }
  .welcome-cta-text { font-size: 0.95rem; }
  .welcome-btn {
    padding: 12px 24px;
    font-size: 0.88rem;
  }

  /* フッター */
  .site-footer { padding: 24px 0 20px; }
  .site-footer-inner { padding: 0 20px; }
  .site-footer-top {
    padding-bottom: 16px;
    margin-bottom: 14px;
    gap: 14px;
  }
  .footer-logo-img { height: 28px; }
  .footer-logo-text { font-size: 11px; }
  .footer-nav { gap: 14px; font-size: 10px; }
  .site-footer-bottom {
    flex-direction: column;
    text-align: center;
    gap: 6px;
  }
  .site-footer-left,
  .site-footer-right { font-size: 0.72rem; }
}

/* ============================================================
   夜モード
   ============================================================ */
body[data-time="night"] {
  --ink: #e8e8e8;
  --ink-soft: #b0b0b0;
  --ink-mute: #888;
  --line: #2a3142;
  --paper: #1a1f2e;
  --cream: #141822;
  --excel-green:    #6dba8e;
  --excel-green-l:  #8ccfaa;
  --excel-green-d:  #4a9d6d;
  --excel-green-ll: #a4d9bc;
  --excel-green-soft: rgba(109, 186, 142, 0.12);
}
body[data-time="night"] .site-header {
  background: var(--paper);
  border-color: var(--line);
}
body[data-time="night"] .welcome-title { color: var(--ink); }
body[data-time="night"] .welcome-section-title { color: var(--ink); }
body[data-time="night"] .welcome-greeting,
body[data-time="night"] .howto-card,
body[data-time="night"] .welcome-cta {
  background: var(--paper);
  border-color: var(--line);
}
body[data-time="night"] .howto-card:hover {
  border-color: var(--excel-green);
  box-shadow: 0 6px 20px rgba(109, 186, 142, 0.1);
}
body[data-time="night"] .welcome-greeting-body strong,
body[data-time="night"] .howto-text strong {
  color: var(--excel-green-ll);
}
body[data-time="night"] .welcome-btn-primary {
  background: var(--excel-green);
  color: #0a0e1a;
  box-shadow: 0 3px 0 var(--excel-green-d);
}
body[data-time="night"] .welcome-btn-primary:hover {
  background: var(--excel-green-l);
}
body[data-time="night"] .welcome-btn-secondary {
  background: var(--paper);
  border-color: var(--excel-green);
  color: var(--excel-green-ll);
}
body[data-time="night"] .welcome-btn-secondary:hover {
  background: var(--excel-green-soft);
}