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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Noto Sans JP", "Hiragino Sans", "Yu Gothic UI", Meiryo, sans-serif;
  color: #1a1a1a;
  background: #f5f5f7;
}

/* ===== ヘッダー ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 12, 20, 0.92);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 800;
  font-size: 20px;
  letter-spacing: 2px;
  color: #fff;
  text-decoration: none;
  white-space: nowrap;
}

.nav ul {
  list-style: none;
  display: flex;
  gap: 8px;
}

.nav a {
  display: block;
  padding: 8px 14px;
  color: #cfd3e0;
  text-decoration: none;
  font-size: 14px;
  letter-spacing: 1px;
  border-radius: 6px;
  transition: color 0.2s, background 0.2s;
}

.nav a:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.08);
}

.nav a.active {
  color: #fff;
  background: rgba(255, 255, 255, 0.12);
}

/* ===== スライダー ===== */
.slider {
  position: relative;
  height: calc(100vh - 64px);
  min-height: 480px;
  overflow: hidden;
}

.slides,
.slide,
.slide img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.slide {
  opacity: 0;
  transition: opacity 1s ease;
}

.slide.active {
  opacity: 1;
}

.slide img {
  object-fit: cover;
}

/* 中央タイトル */
.slide-title {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  z-index: 10;
}

.site-title {
  color: #fff;
  font-size: clamp(40px, 8vw, 110px);
  font-weight: 900;
  letter-spacing: 12px;
  text-shadow: 0 4px 30px rgba(0, 0, 0, 0.7);
  user-select: none;
}

/* ===== スライダー操作ボタン ===== */
.slide-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  z-index: 20;
  width: 48px;
  height: 48px;
  border: none;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.35);
  color: #fff;
  font-size: 22px;
  cursor: pointer;
  transition: background 0.2s;
}

.slide-btn:hover {
  background: rgba(0, 0, 0, 0.6);
}

.slide-btn.prev {
  left: 20px;
}

.slide-btn.next {
  right: 20px;
}

/* ドット */
.slide-dots {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 20;
  display: flex;
  gap: 10px;
}

.slide-dots .dot {
  width: 12px;
  height: 12px;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.4);
  cursor: pointer;
  transition: background 0.2s, transform 0.2s;
}

.slide-dots .dot.active {
  background: #fff;
  transform: scale(1.25);
}

/* ===== セクション ===== */
.section {
  padding: 80px 24px;
}

.section:nth-child(even) {
  background: #fff;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
}

.container h2 {
  font-size: 28px;
  margin-bottom: 16px;
  letter-spacing: 2px;
}

.container p {
  color: #555;
  line-height: 1.9;
}

/* ===== 参加方法 ===== */
.join-steps {
  list-style: none;
  margin-top: 24px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.join-step {
  position: relative;
  background: #fff;
  border: 1px solid #e5e7ec;
  border-radius: 14px;
  padding: 28px 24px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.05);
  transition: transform 0.2s, box-shadow 0.2s;
}

.join-step:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.1);
}

.join-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, #1f3a93, #3a5bd9);
  color: #fff;
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 14px;
}

.join-step h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.join-step p {
  font-size: 14px;
  margin-bottom: 14px;
}

.join-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: linear-gradient(135deg, #5865f2, #7c4dff);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  padding: 10px 18px;
  border-radius: 999px;
  transition: opacity 0.2s;
}

.join-link:hover {
  opacity: 0.85;
}

.join-ip {
  display: inline-block;
  background: #10131a;
  color: #7ce58c;
  font-family: Consolas, "Courier New", monospace;
  font-size: 14px;
  padding: 8px 14px;
  border-radius: 8px;
  user-select: all;
}

.ip-field {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
}

.ip-field:last-child {
  margin-bottom: 0;
}

.ip-label {
  flex: 0 0 auto;
  min-width: 48px;
  font-size: 13px;
  font-weight: 700;
  color: #333;
}

.ip-toggle {
  display: inline-flex;
  background: #e8eaf0;
  border-radius: 999px;
  padding: 4px;
  margin-bottom: 12px;
  gap: 4px;
}

.ip-tab {
  border: none;
  background: transparent;
  color: #666;
  font-size: 14px;
  font-weight: 600;
  padding: 8px 20px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.ip-tab.active {
  background: #fff;
  color: #1f3a93;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12);
}

/* ===== 遊び方 ===== */
.play-content p {
  margin-bottom: 16px;
}

.play-content strong {
  color: #1f3a93;
}

.play-content .accent {
  margin-top: 8px;
  padding: 18px 20px;
  background: #eef2ff;
  border-left: 4px solid #3a5bd9;
  border-radius: 8px;
}

.play-content .accent strong {
  color: #c0392b;
}

/* ===== ルール ===== */
.rule-ch {
  background: #fff;
  border: 1px solid #e5e7ec;
  border-radius: 10px;
  margin-bottom: 12px;
  overflow: hidden;
}

.rule-ch > summary {
  list-style: none;
  cursor: pointer;
  padding: 16px 20px;
  font-size: 17px;
  font-weight: 700;
  color: #1a1a1a;
  position: relative;
  padding-right: 40px;
  transition: background 0.2s;
}

.rule-ch > summary::-webkit-details-marker {
  display: none;
}

.rule-ch > summary:hover {
  background: #f1f3f9;
}

.rule-ch > summary::after {
  content: "+";
  position: absolute;
  right: 18px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 22px;
  font-weight: 400;
  color: #3a5bd9;
  transition: transform 0.2s;
}

.rule-ch[open] > summary::after {
  content: "-";
}

.rule-body {
  padding: 4px 20px 20px;
  border-top: 1px solid #eef0f6;
  overflow: hidden;
  transition: height 0.28s ease;
}

.rule-body h4 {
  font-size: 15px;
  color: #1f3a93;
  margin: 18px 0 8px;
}

.rule-body h4:first-child {
  margin-top: 16px;
}

.rule-body p {
  margin-bottom: 10px;
  font-size: 14px;
}

.rule-list {
  padding-left: 20px;
  margin-bottom: 10px;
}

.rule-list li {
  font-size: 14px;
  line-height: 1.9;
  color: #444;
}

.rule-list .rule-list {
  margin-top: 2px;
}

.rule-body strong {
  color: #1a1a1a;
}

.rule-body .rule-list strong {
  color: #1f3a93;
}

.rule-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 8px;
  font-size: 14px;
}

.rule-table th,
.rule-table td {
  border: 1px solid #e5e7ec;
  padding: 10px 14px;
  text-align: left;
}

.rule-table th {
  background: #1f3a93;
  color: #fff;
  font-weight: 600;
}

.rule-table tr:nth-child(even) td {
  background: #f7f8fc;
}

/* ===== 列島について ===== */
.about-block {
  margin-top: 28px;
}

.about-block > h3 {
  font-size: 22px;
  margin-bottom: 14px;
  padding-left: 12px;
  border-left: 4px solid #3a5bd9;
  color: #1a1a1a;
}

.detail-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.detail {
  flex: 1 1 180px;
  background: #fff;
  border: 1px solid #e5e7ec;
  border-radius: 10px;
  padding: 14px 18px;
}

.detail dt {
  font-size: 12px;
  color: #888;
  letter-spacing: 1px;
  margin-bottom: 4px;
}

.detail dd {
  font-size: 16px;
  font-weight: 700;
  color: #1a1a1a;
}

.theme-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
}

.theme-card {
  background: #fff;
  border: 1px solid #e5e7ec;
  border-radius: 10px;
  padding: 18px;
}

.theme-card p {
  font-size: 14px;
  margin: 10px 0 0;
}

.theme-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  color: #3a5bd9;
  background: #fff;
  border: 2px solid #3a5bd9;
  padding: 3px 12px;
  border-radius: 999px;
  white-space: nowrap;
}

.theme-nogyo {
  color: #2e9e5b;
  border-color: #2e9e5b;
}

.theme-chikusan {
  color: #b5622e;
  border-color: #b5622e;
}

.theme-kotsu {
  color: #8a5bd9;
  border-color: #8a5bd9;
}

.theme-shukuse {
  color: #3a5bd9;
  border-color: #3a5bd9;
}

.theme-build {
  color: #d1467c;
  border-color: #d1467c;
}

.theme-ringyo {
  color: #6b7d2e;
  border-color: #6b7d2e;
}

.theme-sub {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.theme-sub span {
  font-size: 12px;
  font-weight: 700;
  color: #444;
  background: #f2f3f7;
  border: 1px solid #ced2dd;
  border-radius: 999px;
  padding: 4px 12px;
}

.build-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  color: #555;
  background: #fff;
  border: 1px solid #b9bec9;
  border-radius: 999px;
  padding: 3px 10px;
  white-space: nowrap;
}

.build-wa {
  color: #2e6e3e;
  border-color: #2e6e3e;
}

.build-gen {
  color: #1f4f8f;
  border-color: #1f4f8f;
}

.build-sel {
  color: #777;
  border-color: #b0b5bf;
}

.region {
  background: #fff;
  border: 1px solid #e5e7ec;
  border-radius: 10px;
  margin-bottom: 12px;
  overflow: hidden;
  max-width: 560px;
  scroll-margin-top: 90px;
}

.region-body {
  overflow: hidden;
  transition: height 0.28s ease;
}

.region > summary {
  list-style: none;
  cursor: pointer;
  padding: 14px 18px;
  font-size: 16px;
  font-weight: 700;
  color: #1a1a1a;
  position: relative;
  padding-right: 36px;
  transition: background 0.2s;
}

.region > summary::-webkit-details-marker {
  display: none;
}

.region > summary:hover {
  background: #f1f3f9;
}

.region > summary::after {
  content: "+";
  position: absolute;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  font-weight: 400;
  color: #3a5bd9;
}

.region[open] > summary::after {
  content: "-";
}

.region-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  border-top: 1px solid #eef0f6;
}

.region-table th,
.region-table td {
  border-bottom: 1px solid #eef0f6;
  padding: 9px 16px;
  text-align: left;
}

.region-table th {
  background: #f7f8fc;
  color: #333;
  font-weight: 700;
}

/* ===== フッター ===== */
.footer {
  padding: 24px;
  text-align: center;
  background: #10131a;
  color: #8a8f9e;
  font-size: 13px;
}

@media (max-width: 768px) {
  .header-inner {
    height: auto;
    flex-direction: column;
    padding: 12px 16px;
  }

  .nav ul {
    flex-wrap: wrap;
    justify-content: center;
    gap: 4px;
  }

  .nav a {
    font-size: 13px;
    padding: 6px 10px;
  }

  .slider {
    height: calc(100vh - 110px);
  }

  .slide-btn {
    width: 40px;
    height: 40px;
    font-size: 18px;
  }
}