/* ===================================== */
/* 0. 過去ページ専用 背景装飾 */
/* ===================================== */
.archive-page {
  position: relative;
  overflow-x: hidden;
  background-color: #020617;
  /* さらに深い紺 */
  background-image:
    /* 極薄のグリッド */
    linear-gradient(rgba(59, 130, 246, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59, 130, 246, 0.03) 1px, transparent 1px);
  background-size: 80px 80px;
}

/* 浮遊する光の塊 */
.archive-page::before,
.archive-page::after {
  content: "";
  position: fixed;
  width: 800px;
  height: 800px;
  border-radius: 50%;
  pointer-events: none;
  z-index: -1;
  filter: blur(120px);
  opacity: 0.15;
}

.archive-page::before {
  top: -200px;
  right: -200px;
  background: radial-gradient(circle, #3b82f6 0%, transparent 70%);
  animation: float 20s infinite alternate ease-in-out;
}

.archive-page::after {
  bottom: -200px;
  left: -200px;
  background: radial-gradient(circle, #8b5cf6 0%, transparent 70%);
  animation: float 25s infinite alternate-reverse ease-in-out;
}

@keyframes float {
  0% {
    transform: translate(0, 0) scale(1);
  }

  50% {
    transform: translate(-100px, 50px) scale(1.1);
  }

  100% {
    transform: translate(50px, -50px) scale(0.9);
  }
}

/* 背景をより深く見せるためのオーバーレイ */
.archive-page main {
  position: relative;
  z-index: 1;
}

/* ===================================== */
/* 1. 年別索引（TOC） */
/* ===================================== */
/* ===================================== */
/* 1. 年度切り替えタブ (Segmented Control) */
/* ===================================== */
.archive-tabs-container {
  display: flex;
  justify-content: center;
  margin-bottom: 60px;
}

.archive-tabs {
  position: relative;
  display: flex;
  background: rgba(17, 24, 39, 0.8);
  border: 1px solid rgba(255, 255, 255, 0.05);
  padding: 6px;
  border-radius: 99px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.tab-btn {
  position: relative;
  padding: 10px 32px;
  font-size: 14px;
  font-weight: 700;
  color: var(--text-muted);
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: 2;
  transition: color 0.3s ease;
  white-space: nowrap;
}

.tab-btn.active {
  color: #fff;
}

.tab-slider {
  position: absolute;
  top: 6px;
  left: 6px;
  height: calc(100% - 12px);
  background: var(--gradient-primary);
  border-radius: 99px;
  z-index: 1;
  transition: all 0.4s cubic-bezier(0.19, 1, 0.22, 1);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

/* ===================================== */
/* 2. コンテンツ表示制御 */
/* ===================================== */
.year-content {
  display: none;
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.5s cubic-bezier(0.19, 1, 0.22, 1);
}

.year-content.active {
  display: block;
  opacity: 1;
  transform: translateY(0);
}

/* ===================================== */
/* 2. 年見出し */
/* ===================================== */
.year-heading {
  font-size: 24px;
  font-weight: 700;
  color: #fff;
  margin-top: 60px;
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 16px;
  padding-left: 8px;
  width: 100%;
  /* 幅を確保 */
}

.year-heading::after {
  content: "";
  flex: 1;
  height: 1px;
  background: linear-gradient(to right, var(--border-subtle), transparent);
}

/* ===================================== */
/* 3. セミナーカード（PC用デフォルト） */
/* ===================================== */
.seminar-card {
  background: var(--card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  margin-bottom: 20px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.seminar-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--gradient-primary);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.seminar-card:hover {
  transform: translateY(-2px);
  border-color: rgba(59, 130, 246, 0.4);
  box-shadow: 0 10px 30px -5px rgba(0, 0, 0, 0.3);
}

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

/* ヘッダー部分 */
.seminar-header {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: center;
  padding: 24px;
  user-select: none;
}

/* PC用のタイトルサイズ */
.seminar-title {
  margin: 0;
  font-size: 18px;
  /* PCでは大きく */
  font-weight: 600;
  color: var(--text);
  line-height: 1.4;
  transition: color 0.3s ease;
}

.seminar-card:hover .seminar-title {
  color: #fff;
}

/* 開閉アイコン */
.toggle-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.05);
  color: var(--accent);
  font-size: 18px;
  transition: all 0.3s ease;
}

.seminar-card:hover .toggle-icon {
  background: var(--accent);
  color: #fff;
}

.seminar-header.open .toggle-icon {
  transform: rotate(45deg);
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-muted);
}

/* セミナー情報のリスト（PC用：横並び） */
.seminar-info-list {
  list-style: none;
  padding: 0 24px 20px;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  /* 縦位置中央揃え */
  gap: 20px;
  font-size: 13px;
  color: var(--text-muted);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease;

  /* 重要：PCでは flex-direction: row (横並び) がデフォルトです */
}

.seminar-header.open+.seminar-info-list {
  border-bottom-color: var(--border-subtle);
}

.seminar-info-list li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.seminar-info-list strong {
  font-weight: 600;
  color: #94a3b8;
  background: rgba(255, 255, 255, 0.05);
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* 概要部分 */
.seminar-abstract {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1), padding 0.4s ease;
  padding: 0 24px;
  background: rgba(0, 0, 0, 0.2);
}

.seminar-abstract.open {
  max-height: 1000px;
  padding: 24px;
}

.seminar-abstract p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: #cbd5e1;
}

/* ===================================== */
/* 4. スマホ用レスポンシブ設定 (640px以下) */
/* ===================================== */
/* このブロックの中身はスマホでのみ有効になります */
@media (max-width: 640px) {

  /* タイトルを少し小さく */
  .seminar-title {
    font-size: 15px;
    line-height: 1.5;
  }

  /* リストを縦並びにする（スマホのみ！） */
  .seminar-info-list {
    flex-direction: column;
    /* 縦並び */
    align-items: flex-start;
    /* 左寄せ */
    gap: 8px;
    padding: 0 16px 16px;
  }

  /* 概要部分の余白調整 */
  .seminar-abstract.open {
    padding: 16px;
  }

  .seminar-abstract p {
    font-size: 14px;
    word-wrap: break-word;
  }
}

/* ===================================== */
/* 5. ヘッダー調整 */
/* ===================================== */
.archive-header {
  position: relative;
  overflow: hidden;
  padding: 40px 0;
}

.header-content {
  position: relative;
  z-index: 2;
}

/* 元のTOCリンクを抹消 */
.archive-toc {
  display: none !important;
}

/* ===================================== */
/* 5. 設立経緯 (Origins Card) */
/* ===================================== */
.origin-card {
  background: linear-gradient(135deg, rgba(88, 28, 135, 0.1) 0%, rgba(17, 24, 39, 0.4) 100%);
  border: 1px solid rgba(139, 92, 246, 0.2);
  border-radius: 24px;
  padding: 32px;
  margin-bottom: 40px;
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
}

.origin-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(to bottom, #8b5cf6, #3b82f6);
}

.origin-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  font-weight: 800;
  color: #a78bfa;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 16px;
}

.origin-title {
  font-size: 20px;
  font-weight: 700;
  color: #fff;
  margin-bottom: 24px;
}

.origin-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.origin-link-item {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 16px;
  background: rgba(255, 255, 255, 0.03);
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.05);
  transition: all 0.3s ease;
}

.origin-link-item:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(139, 92, 246, 0.3);
  transform: translateY(-2px);
}

.origin-link-label {
  font-size: 13px;
  font-weight: 600;
  color: #cbd5e1;
}

.origin-link-url {
  font-size: 13px;
  color: #60a5fa;
  word-break: break-all;
  display: flex;
  align-items: center;
  gap: 6px;
}

.origin-link-url i {
  font-size: 11px;
}

@media (max-width: 768px) {
  .origin-card {
    padding: 24px;
  }

  .origin-title {
    font-size: 18px;
  }
}