/* ============================================
   思考經典學堂 — 溫暖、低飽和、手機友善樣式
   ============================================ */

/* --- 設計變數（溫潤米白／深灰／墨綠）--- */
:root {
  --color-bg: #FDFBF7;
  --color-text: #333333;
  --color-heading: #2D433D;
  --color-muted: #5C6B65;
  --color-border: #E8E4DE;
  --color-link: #3D5A52;
  --color-link-hover: #2D433D;
  --font-size-body: 18px;
  --line-height-body: 1.8;
  --space-paragraph: 1.5em;
  --space-section: 2.5rem;
  --max-width-content: 52rem;
  --radius: 6px;
}

/* --- 基礎重置與全域 --- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 100%;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-size: var(--font-size-body);
  line-height: var(--line-height-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  font-family: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- 語義化區塊：header --- */
.site-header {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 1.25rem;
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner {
  max-width: var(--max-width-content);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-name {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-heading);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.site-name:hover {
  color: var(--color-link-hover);
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
}

.site-nav a {
  color: var(--color-muted);
  text-decoration: none;
  font-size: 0.95rem;
}

.site-nav a:hover {
  color: var(--color-heading);
}

/* --- 語義化區塊：main --- */
.main {
  flex: 1;
  width: 100%;
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 1.25rem 1.25rem 2.5rem;
}

/* --- 語義化區塊：section（首頁）--- */
.home-intro {
  margin-bottom: var(--space-section);
}

.home-title {
  font-size: 1.75rem;
  color: var(--color-heading);
  margin: 0 0 0.5em;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.home-tagline {
  color: var(--color-muted);
  margin: 0;
  font-size: 1rem;
}

.section-title {
  font-size: 1.15rem;
  color: var(--color-heading);
  margin: 0 0 1rem;
  font-weight: 600;
}

.section-desc {
  color: var(--color-muted);
  font-size: 0.95rem;
  margin: -0.5rem 0 1rem;
}

.section-more {
  margin: 1rem 0 0;
}

.section-more a {
  color: var(--color-link);
  text-decoration: none;
  font-size: 0.95rem;
}

.section-more a:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

/* --- 故事目錄（首頁置頂 + 目錄頁）--- */
.story-catalog-top {
  margin-bottom: var(--space-section);
  padding-bottom: var(--space-section);
  border-bottom: 1px solid var(--color-border);
}

.catalog-series {
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: catalog;
}

.catalog-series-item {
  counter-increment: catalog;
  padding: 0.75em 0;
  border-bottom: 1px solid var(--color-border);
}

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

.catalog-series-link {
  display: block;
  color: var(--color-link);
  text-decoration: none;
  font-weight: 500;
}

.catalog-series-link:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

.catalog-series-title::before {
  content: counter(catalog) ". ";
  color: var(--color-muted);
  font-weight: 400;
}

.catalog-series-desc {
  margin: 0.35em 0 0 1.5em;
  font-size: 0.9rem;
  color: var(--color-muted);
  line-height: 1.5;
}

.catalog-series--compact .catalog-series-desc {
  display: none;
}

.catalog-series--compact .catalog-series-item {
  padding: 0.45em 0;
}

.catalog-series--compact .catalog-series-title::before {
  content: counter(catalog) ". ";
}

.story-catalog-list .catalog-series {
  margin-top: 0.5rem;
}

.vault-preview {
  margin-top: var(--space-section);
  padding-top: var(--space-section);
  border-top: 1px solid var(--color-border);
}

.section-header {
  margin-bottom: var(--space-section);
}

.section-header .section-desc {
  margin: 0.25em 0 0;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.post-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.post-list li {
  padding: 0.6em 0;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.75em;
}

.post-list a {
  color: var(--color-link);
  text-decoration: none;
  flex: 1 1 auto;
}

.post-list a:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

.post-list time {
  font-size: 0.9rem;
  color: var(--color-muted);
}

.no-posts {
  color: var(--color-muted);
}

/* --- 文章頁：article（h1 唯一標題、h2 故事轉折小標）--- */
.article {
  max-width: 100%;
}

.article-header {
  margin-bottom: var(--space-section);
}

.article-title {
  font-size: 1.65rem;
  color: var(--color-heading);
  margin: 0 0 0.4em;
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: 0.02em;
}

.article-date {
  font-size: 0.95rem;
  color: var(--color-muted);
}

/* 字體呼吸感：字距稍寬，抒情文體更有質感 */
.article-content {
  margin: 0;
  letter-spacing: 0.05em;
}

/* KaTeX 數學公式：區塊公式與內文協調 */
.article-content .katex-display {
  margin: 1em 0;
  overflow-x: auto;
  overflow-y: hidden;
}
.article-content .katex {
  font-size: 1.1em;
}

/* 內文：段落間距大，方便手機滑動閱讀 */
.article-content p {
  margin: 0 0 var(--space-paragraph);
}

.article-content p:last-child {
  margin-bottom: 0;
}

/* 故事轉折小標 h2 */
.article-content h2 {
  font-size: 1.25rem;
  color: var(--color-heading);
  margin: 2em 0 0.75em;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: 0.02em;
}

.article-content h2:first-of-type {
  margin-top: 1.5em;
}

/* 避免文章內誤用 h1，僅保留一個 h1 在 .article-title */
.article-content h1 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-heading);
  margin: 1.5em 0 0.6em;
}

.article-content h3,
.article-content h4 {
  font-size: 1.1rem;
  color: var(--color-heading);
  margin: 1.4em 0 0.5em;
  font-weight: 600;
}

.article-content ul,
.article-content ol {
  margin: 0 0 var(--space-paragraph);
  padding-left: 1.5em;
}

.article-content li {
  margin-bottom: 0.4em;
}

.article-content blockquote {
  margin: var(--space-paragraph) 0;
  padding: 0.8em 1.2em;
  border-left: 4px solid var(--color-border);
  background: rgba(45, 67, 61, 0.04);
  color: var(--color-muted);
  border-radius: 0 var(--radius) var(--radius) 0;
}

.article-content blockquote p:last-child {
  margin-bottom: 0;
}

.article-content a {
  color: var(--color-link);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.article-content a:hover {
  color: var(--color-link-hover);
}

.article-content img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  margin: var(--space-paragraph) 0;
}

.article-content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2em 0;
}

/* --- 文章內「下一集」導覽（nav + rel="next"）--- */
.article-nav-next {
  margin-top: 2.5rem;
}

.article-nav-next-btn {
  display: block;
  width: 100%;
  padding: 1rem 1.25rem;
  font-size: 18px;
  line-height: 1.5;
  color: #fff;
  background-color: #2D433D;
  text-align: center;
  text-decoration: none;
  border: none;
  border-radius: var(--radius);
  transition: background-color 0.25s ease, box-shadow 0.25s ease;
  -webkit-tap-highlight-color: transparent;
}

.article-nav-next-btn:hover {
  background-color: #3d5a52;
  box-shadow: 0 4px 12px rgba(45, 67, 61, 0.25);
}

.article-nav-next-btn:active {
  background-color: #2a3d36;
}

.article-nav-next-btn.article-nav-back {
  background-color: var(--color-muted);
}

.article-nav-next-btn.article-nav-back:hover {
  background-color: var(--color-heading);
  box-shadow: 0 4px 12px rgba(45, 67, 61, 0.2);
}

/* --- 語義化區塊：footer --- */
.site-footer {
  background: rgba(232, 228, 222, 0.6);
  border-top: 1px solid var(--color-border);
  padding: 1.25rem 1.25rem;
  margin-top: auto;
}

.footer-inner {
  max-width: var(--max-width-content);
  margin: 0 auto;
  text-align: center;
}

.site-footer p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--color-muted);
}

/* --- 下一集按鈕（僅手機、滑動 30% 後顯示）--- */
.next-episode-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 20;
  padding: 0.75rem 1.25rem;
  padding-bottom: max(0.75rem, env(safe-area-inset-bottom));
  background: rgba(253, 251, 247, 0.98);
  border-top: 1px solid var(--color-border);
  box-shadow: 0 -4px 12px rgba(45, 67, 61, 0.08);
  opacity: 0;
  transform: translateY(100%);
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.next-episode-bar--visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.next-episode-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 0.4em 0;
  color: var(--color-link);
  text-decoration: none;
  font-size: 0.95rem;
  text-align: center;
}

.next-episode-link:hover {
  color: var(--color-link-hover);
}

.next-episode-label {
  font-size: 0.8rem;
  color: var(--color-muted);
  letter-spacing: 0.05em;
}

.next-episode-title {
  font-weight: 500;
  color: var(--color-heading);
}

/* 僅在手機顯示此區塊（與 JS 判斷一致）*/
@media (min-width: 769px) {
  .next-episode-bar {
    display: none;
  }
}

/* --- 手機優先：較大螢幕微調（版面加寬、適度減少空白）--- */
@media (min-width: 640px) {
  .main {
    padding: 1.5rem 1.25rem 2.5rem;
  }

  .article-title {
    font-size: 1.85rem;
  }

  .article-content h2 {
    font-size: 1.35rem;
  }

  .home-title {
    font-size: 2rem;
  }
}