/* ===== リセット・基本設定 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #f9f9f7;
  --color-surface: #ffffff;
  --color-text: #1a1a1a;
  --color-text-muted: #6b6b6b;
  --color-accent: #2c5f8a;
  --color-accent-light: #e8f0f7;
  --color-border: #e5e5e5;
  --color-tag-bg: #f0f4f8;
  --font-sans: 'Noto Sans JP', 'Helvetica Neue', Arial, sans-serif;
  --radius: 8px;
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  font-size: 16px;
}

a {
  color: var(--color-accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* ===== ヘッダー ===== */
header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: 0.02em;
}

.site-title a {
  color: inherit;
}

nav {
  display: flex;
  gap: 28px;
}

nav a {
  font-size: 14px;
  color: var(--color-text-muted);
  font-weight: 500;
  transition: color 0.2s;
}

nav a:hover, nav a.active {
  color: var(--color-accent);
  text-decoration: none;
}

nav a.nav-home {
  background: var(--color-accent);
  color: #fff;
  padding: 5px 14px;
  border-radius: 100px;
  font-size: 13px;
  font-weight: 600;
  transition: opacity 0.2s;
}

nav a.nav-home:hover {
  opacity: 0.85;
  color: #fff;
  text-decoration: none;
}

/* ===== メインコンテンツ ===== */
main {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px 80px;
}

/* ===== ヒーローセクション ===== */
.hero {
  margin-top: 40px;
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
  background: #1a1a1a;
}

.hero img {
  width: 100%;
  max-height: 420px;
  object-fit: cover;
  display: block;
  opacity: 0.92;
}

.hero-text {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 32px 36px;
  background: linear-gradient(to top, rgba(0,0,0,0.65) 0%, transparent 100%);
  color: #fff;
}

.hero-text h1 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: 0.02em;
}

.hero-text p {
  font-size: 14px;
  opacity: 0.88;
}

/* ===== セクション共通 ===== */
section {
  margin-top: 56px;
}

.section-title {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 24px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-accent);
  display: inline-block;
}

/* ===== 記事一覧 ===== */
.article-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.article-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: box-shadow 0.2s;
  cursor: pointer;
}

.article-card:hover {
  box-shadow: var(--shadow);
}

.article-meta {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.article-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.tag {
  background: var(--color-tag-bg);
  color: var(--color-accent);
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 100px;
  font-weight: 500;
}

.article-card {
  display: block;
  color: inherit;
  text-decoration: none !important;
}

.article-thumb {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
  border-radius: 4px;
  margin-bottom: 10px;
  display: block;
}

.article-card h2 {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--color-text);
  line-height: 1.5;
}

.article-card p {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.6;
}

.article-source-link {
  display: inline-block;
  margin-top: 10px;
  font-size: 12px;
  color: var(--color-accent);
  font-weight: 500;
}

/* ===== カテゴリタブ ===== */
.category-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.tab-btn {
  padding: 7px 16px;
  border: 1px solid var(--color-border);
  border-radius: 100px;
  background: var(--color-surface);
  color: var(--color-text-muted);
  font-size: 13px;
  font-weight: 500;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.tab-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.tab-btn.active {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

/* ===== 過去記事リンク ===== */
.archive-link-wrap {
  margin-top: 20px;
  text-align: right;
}

.archive-link {
  font-size: 13px;
  color: var(--color-accent);
  font-weight: 500;
}

.archive-link:hover {
  text-decoration: underline;
}

/* ===== アーカイブページ 検索 ===== */
.archive-search {
  margin-bottom: 20px;
}

.archive-search input {
  width: 100%;
  max-width: 400px;
  padding: 10px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 14px;
  font-family: var(--font-sans);
  background: var(--color-surface);
  outline: none;
  transition: border-color 0.2s;
}

.archive-search input:focus {
  border-color: var(--color-accent);
}

/* ===== YouTube動画一覧 ===== */
.youtube-section {
  margin-top: 56px;
}

.video-toolbar {
  display: flex;
  gap: 10px;
  margin-bottom: 24px;
  align-items: center;
}

.video-toolbar input {
  flex: 1;
  padding: 10px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 14px;
  font-family: var(--font-sans);
  background: var(--color-surface);
  outline: none;
  transition: border-color 0.2s;
}

.video-toolbar input:focus {
  border-color: var(--color-accent);
}

.channel-link-btn {
  display: inline-block;
  padding: 10px 18px;
  background: #ff0000;
  color: #fff !important;
  border-radius: var(--radius);
  font-size: 13px;
  font-weight: 600;
  white-space: nowrap;
  transition: opacity 0.2s;
  text-decoration: none !important;
}

.channel-link-btn:hover {
  opacity: 0.85;
}

#load-more-btn {
  padding: 12px 36px;
  background: var(--color-accent);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: opacity 0.2s;
}

#load-more-btn:hover {
  opacity: 0.85;
}

#load-more-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.video-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: box-shadow 0.2s;
}

.video-card:hover {
  box-shadow: var(--shadow);
}

.video-card img {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
  display: block;
}

.video-card-body {
  padding: 12px 14px;
}

.video-card-body h3 {
  font-size: 13px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--color-text);
  margin-bottom: 4px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-card-body p {
  font-size: 11px;
  color: var(--color-text-muted);
}

.search-message {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 14px;
  padding: 40px 0;
}

.api-notice {
  background: var(--color-accent-light);
  border: 1px solid #c0d8ee;
  border-radius: var(--radius);
  padding: 14px 18px;
  font-size: 13px;
  color: var(--color-accent);
  margin-bottom: 20px;
}

/* ===== フッター ===== */
footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  text-align: center;
  padding: 24px;
  font-size: 12px;
  color: var(--color-text-muted);
  margin-top: 80px;
}

/* ===== レスポンシブ ===== */
@media (max-width: 640px) {
  .header-inner {
    padding: 0 16px;
  }

  main {
    padding: 0 16px 60px;
  }

  .hero-text h1 {
    font-size: 18px;
  }

  nav {
    gap: 16px;
  }

  .video-grid {
    grid-template-columns: 1fr;
  }

  .video-toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .channel-link-btn {
    text-align: center;
  }
}