:root {
  --primary: #2563eb;
  --primary-light: #eff6ff;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --orange: #f5a623;
  
  /* 試験区分カラー */
  --color-sap: #d97706;
  --color-sap-light: #fef3c7;
  --color-saa: #2563eb;
  --color-saa-light: #dbeafe;
  --color-soa: #059669;
  --color-soa-light: #d1fae5;
  --color-scs: #db2777;
  --color-scs-light: #fce7f3;
  --color-dva: #7c3aed;
  --color-dva-light: #ede9fe;
  --color-ans: #0891b2;
  --color-ans-light: #cffafe;
  --color-dop: #ea580c;
  --color-dop-light: #ffedd5;
  --color-aif: #4f46e5;
  --color-aif-light: #e0e7ff;
  --color-dea: #0d9488;
  --color-dea-light: #ccfbf1;
  --color-mla: #c026d3;
  --color-mla-light: #fae8ff;
  --color-mls: #be123c;
  --color-mls-light: #ffe4e6;
}

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

body {
  font-family: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 2.5rem 1.25rem;
}

/* アニメーション定義 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

/* ヘッダー */
header {
  text-align: center;
  margin-bottom: 2.5rem;
  animation: fadeInUp 0.6s ease-out;
}

.logo {
  width: 180px;
  height: auto;
  margin-bottom: 1.25rem;
  animation: scaleIn 0.5s ease-out;
}

h1 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.5rem;
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* 統計 */
.stats {
  display: flex;
  justify-content: center;
  gap: 3rem;
  margin: 1.5rem 0;
}

.stat-item {
  text-align: center;
  animation: fadeInUp 0.6s ease-out;
  animation-fill-mode: both;
}

.stat-item:nth-child(1) { animation-delay: 0.1s; }
.stat-item:nth-child(2) { animation-delay: 0.2s; }

.stat-number {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--orange);
  line-height: 1.2;
  transition: transform 0.3s ease;
}

.stat-number.counting {
  transform: scale(1.1);
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* フィルタータブ */
.filter-tabs {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  animation: fadeIn 0.4s ease-out 0.3s both;
}

.filter-tab {
  padding: 0.5rem 1rem;
  border: 2px solid var(--border);
  border-radius: 20px;
  background: var(--card-bg);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.25s ease;
}

/* デフォルト（すべて）のホバー */
.filter-tab:hover {
  border-color: var(--orange);
  color: var(--orange);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(245, 166, 35, 0.2);
}

/* 試験区分ごとのホバー色 */
.filter-tab[data-exam="sap"]:hover {
  border-color: var(--color-sap);
  color: var(--color-sap);
  box-shadow: 0 4px 12px rgba(217, 119, 6, 0.2);
}

.filter-tab[data-exam="saa"]:hover {
  border-color: var(--color-saa);
  color: var(--color-saa);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.filter-tab[data-exam="soa"]:hover {
  border-color: var(--color-soa);
  color: var(--color-soa);
  box-shadow: 0 4px 12px rgba(5, 150, 105, 0.2);
}

.filter-tab[data-exam="scs"]:hover {
  border-color: var(--color-scs);
  color: var(--color-scs);
  box-shadow: 0 4px 12px rgba(219, 39, 119, 0.2);
}

.filter-tab[data-exam="dva"]:hover {
  border-color: var(--color-dva);
  color: var(--color-dva);
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.2);
}

.filter-tab[data-exam="ans"]:hover {
  border-color: var(--color-ans);
  color: var(--color-ans);
  box-shadow: 0 4px 12px rgba(8, 145, 178, 0.2);
}

.filter-tab[data-exam="dop"]:hover {
  border-color: var(--color-dop);
  color: var(--color-dop);
  box-shadow: 0 4px 12px rgba(234, 88, 12, 0.2);
}

.filter-tab[data-exam="aif"]:hover {
  border-color: var(--color-aif);
  color: var(--color-aif);
  box-shadow: 0 4px 12px rgba(79, 70, 229, 0.2);
}

.filter-tab[data-exam="dea"]:hover {
  border-color: var(--color-dea);
  color: var(--color-dea);
  box-shadow: 0 4px 12px rgba(13, 148, 136, 0.2);
}

.filter-tab[data-exam="mla"]:hover {
  border-color: var(--color-mla);
  color: var(--color-mla);
  box-shadow: 0 4px 12px rgba(192, 38, 211, 0.2);
}

.filter-tab[data-exam="mls"]:hover {
  border-color: var(--color-mls);
  color: var(--color-mls);
  box-shadow: 0 4px 12px rgba(190, 18, 60, 0.2);
}

/* アクティブ状態 */
.filter-tab.active {
  background: var(--orange);
  border-color: var(--orange);
  color: white;
  transform: translateY(0);
  box-shadow: 0 2px 8px rgba(245, 166, 35, 0.3);
}

/* アクティブ状態のホバー（文字色を白に保つ） */
.filter-tab.active:hover {
  color: white;
  transform: translateY(-2px);
}

/* 試験区分ごとのアクティブ色 */
.filter-tab[data-exam="sap"].active {
  background: var(--color-sap);
  border-color: var(--color-sap);
  box-shadow: 0 2px 8px rgba(217, 119, 6, 0.3);
}
.filter-tab[data-exam="sap"].active:hover {
  background: var(--color-sap);
  border-color: var(--color-sap);
  color: white;
  box-shadow: 0 6px 16px rgba(217, 119, 6, 0.35);
}

.filter-tab[data-exam="saa"].active {
  background: var(--color-saa);
  border-color: var(--color-saa);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}
.filter-tab[data-exam="saa"].active:hover {
  background: var(--color-saa);
  border-color: var(--color-saa);
  color: white;
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.35);
}

.filter-tab[data-exam="soa"].active {
  background: var(--color-soa);
  border-color: var(--color-soa);
  box-shadow: 0 2px 8px rgba(5, 150, 105, 0.3);
}
.filter-tab[data-exam="soa"].active:hover {
  background: var(--color-soa);
  border-color: var(--color-soa);
  color: white;
  box-shadow: 0 6px 16px rgba(5, 150, 105, 0.35);
}

.filter-tab[data-exam="scs"].active {
  background: var(--color-scs);
  border-color: var(--color-scs);
  box-shadow: 0 2px 8px rgba(219, 39, 119, 0.3);
}
.filter-tab[data-exam="scs"].active:hover {
  background: var(--color-scs);
  border-color: var(--color-scs);
  color: white;
  box-shadow: 0 6px 16px rgba(219, 39, 119, 0.35);
}

.filter-tab[data-exam="dva"].active {
  background: var(--color-dva);
  border-color: var(--color-dva);
  box-shadow: 0 2px 8px rgba(124, 58, 237, 0.3);
}
.filter-tab[data-exam="dva"].active:hover {
  background: var(--color-dva);
  border-color: var(--color-dva);
  color: white;
  box-shadow: 0 6px 16px rgba(124, 58, 237, 0.35);
}

.filter-tab[data-exam="ans"].active {
  background: var(--color-ans);
  border-color: var(--color-ans);
  box-shadow: 0 2px 8px rgba(8, 145, 178, 0.3);
}
.filter-tab[data-exam="ans"].active:hover {
  background: var(--color-ans);
  border-color: var(--color-ans);
  color: white;
  box-shadow: 0 6px 16px rgba(8, 145, 178, 0.35);
}

.filter-tab[data-exam="dop"].active {
  background: var(--color-dop);
  border-color: var(--color-dop);
  box-shadow: 0 2px 8px rgba(234, 88, 12, 0.3);
}
.filter-tab[data-exam="dop"].active:hover {
  background: var(--color-dop);
  border-color: var(--color-dop);
  color: white;
  box-shadow: 0 6px 16px rgba(234, 88, 12, 0.35);
}

.filter-tab[data-exam="aif"].active {
  background: var(--color-aif);
  border-color: var(--color-aif);
  box-shadow: 0 2px 8px rgba(79, 70, 229, 0.3);
}
.filter-tab[data-exam="aif"].active:hover {
  background: var(--color-aif);
  border-color: var(--color-aif);
  color: white;
  box-shadow: 0 6px 16px rgba(79, 70, 229, 0.35);
}

.filter-tab[data-exam="dea"].active {
  background: var(--color-dea);
  border-color: var(--color-dea);
  box-shadow: 0 2px 8px rgba(13, 148, 136, 0.3);
}
.filter-tab[data-exam="dea"].active:hover {
  background: var(--color-dea);
  border-color: var(--color-dea);
  color: white;
  box-shadow: 0 6px 16px rgba(13, 148, 136, 0.35);
}

.filter-tab[data-exam="mla"].active {
  background: var(--color-mla);
  border-color: var(--color-mla);
  box-shadow: 0 2px 8px rgba(192, 38, 211, 0.3);
}
.filter-tab[data-exam="mla"].active:hover {
  background: var(--color-mla);
  border-color: var(--color-mla);
  color: white;
  box-shadow: 0 6px 16px rgba(192, 38, 211, 0.35);
}

.filter-tab[data-exam="mls"].active {
  background: var(--color-mls);
  border-color: var(--color-mls);
  box-shadow: 0 2px 8px rgba(190, 18, 60, 0.3);
}
.filter-tab[data-exam="mls"].active:hover {
  background: var(--color-mls);
  border-color: var(--color-mls);
  color: white;
  box-shadow: 0 6px 16px rgba(190, 18, 60, 0.35);
}

.filter-tab .tab-count {
  font-size: 0.75rem;
  opacity: 0.8;
  margin-left: 0.25rem;
}

/* セクション */
.history-section {
  margin-bottom: 1.5rem;
  opacity: 0;
  transform: translateY(15px);
  animation: fadeInUp 0.5s ease-out forwards;
}

.history-section:nth-child(1) { animation-delay: 0.1s; }
.history-section:nth-child(2) { animation-delay: 0.15s; }
.history-section:nth-child(3) { animation-delay: 0.2s; }
.history-section:nth-child(4) { animation-delay: 0.25s; }
.history-section:nth-child(5) { animation-delay: 0.3s; }

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem;
  background: var(--card-bg);
  border-radius: 8px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all 0.25s ease;
  user-select: none;
}

.section-header:hover {
  background: #fef6e8;
  transform: translateX(4px);
}

.section-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
  margin: 0;
  padding: 0;
  border: none;
}

.section-count {
  font-size: 0.75rem;
  font-weight: 600;
  color: white;
  background: var(--orange);
  padding: 0.2rem 0.6rem;
  border-radius: 12px;
}

.section-toggle {
  width: 20px;
  height: 20px;
  color: var(--text-muted);
  transition: transform 0.3s ease;
}

.history-section.open .section-toggle {
  transform: rotate(180deg);
}

.history-list {
  display: none;
  flex-direction: column;
  gap: 1.25rem;
  margin-top: 1rem;
  padding-left: 0.5rem;
}

.history-section.open .history-list {
  display: flex;
}

/* 日付カード */
.date-card {
  background: var(--card-bg);
  border-radius: 12px;
  box-shadow: var(--shadow);
  overflow: hidden;
  opacity: 0;
  transform: translateY(10px);
  animation: fadeInUp 0.4s ease-out forwards;
}

.date-card:nth-child(1) { animation-delay: 0.05s; }
.date-card:nth-child(2) { animation-delay: 0.1s; }
.date-card:nth-child(3) { animation-delay: 0.15s; }
.date-card:nth-child(4) { animation-delay: 0.2s; }
.date-card:nth-child(5) { animation-delay: 0.25s; }

.date-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  background: #fef6e8;
  border-bottom: 1px solid var(--border);
}

.date-badge {
  background: var(--orange);
  color: white;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
}

.date-count {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* アイテムリスト */
.items-list {
  padding: 0.5rem 0;
}

.history-item {
  display: flex;
  gap: 0.75rem;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--border);
  transition: background 0.2s ease;
}

.history-item:hover {
  background: #fafafa;
}

.history-item:last-child {
  border-bottom: none;
}

.item-id {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.problem-id {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text);
}

/* 試験バッジ */
.exam-badge {
  font-size: 0.6rem;
  font-weight: 600;
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  text-transform: uppercase;
  letter-spacing: 0.3px;
}

.exam-sap { background: var(--color-sap-light); color: #92400e; }
.exam-saa { background: var(--color-saa-light); color: #1e40af; }
.exam-soa { background: var(--color-soa-light); color: #065f46; }
.exam-scs { background: var(--color-scs-light); color: #9d174d; }
.exam-dva { background: var(--color-dva-light); color: #5b21b6; }
.exam-ans { background: var(--color-ans-light); color: #0e7490; }
.exam-dop { background: var(--color-dop-light); color: #c2410c; }
.exam-aif { background: var(--color-aif-light); color: #3730a3; }
.exam-dea { background: var(--color-dea-light); color: #0f766e; }
.exam-mla { background: var(--color-mla-light); color: #a21caf; }
.exam-mls { background: var(--color-mls-light); color: #9f1239; }

.item-summary {
  flex: 1;
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* フッター */
footer {
  text-align: center;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.85rem;
  animation: fadeIn 0.5s ease-out 0.5s both;
}

footer a {
  color: var(--orange);
  text-decoration: none;
  transition: color 0.2s ease;
}

footer a:hover {
  color: #e09000;
  text-decoration: underline;
}

/* ローディング・エラー */
.loading {
  text-align: center;
  padding: 3rem;
  color: var(--text-muted);
  animation: fadeIn 0.3s ease-out;
}

.error {
  text-align: center;
  padding: 2rem;
  color: #dc2626;
  background: #fef2f2;
  border-radius: 8px;
  animation: fadeIn 0.3s ease-out;
}

/* レスポンシブ */
@media (max-width: 600px) {
  .container {
    padding: 1.5rem 1rem;
  }
  
  .logo {
    width: 140px;
  }
  
  h1 {
    font-size: 1.4rem;
  }

  .stats {
    gap: 2rem;
  }

  .stat-number {
    font-size: 1.75rem;
  }

  .history-item {
    flex-direction: column;
    gap: 0.4rem;
  }

  .item-summary {
    padding-left: 0;
  }
  
  .filter-tab:hover {
    transform: none;
  }
}