/* =============================================================
   chenlang.info — Design System
   东方人文风 · Eastern Humanistic Aesthetic
   ============================================================= */

/* ---------------------------------------------------------------
   1. Custom Properties
--------------------------------------------------------------- */
:root {
  /* Backgrounds */
  --color-paper:        #F5F0E8;
  --color-paper-dark:   #EDE7D9;
  --color-paper-rule:   #D8CFBE;

  /* Text */
  --color-ink:          #1C1A16;
  --color-ink-secondary:#4A4538;
  --color-ink-muted:    #7A7162;

  /* Accent: 朱砂红 Cinnabar Red */
  --color-accent:       #B5341C;
  --color-accent-hover: #8C2414;

  /* Secondary: 深靛蓝 Deep Indigo */
  --color-indigo:       #2C3E6E;

  /* Font families */
  --font-serif-zh: 'Noto Serif SC', 'Songti SC', 'STSong', 'SimSun', serif;
  --font-serif-en: 'EB Garamond', 'Garamond', 'Times New Roman', serif;
  --font-base:     var(--font-serif-zh);

  /* Type scale — Major Third (×1.250) */
  --text-xs:    0.64rem;
  --text-sm:    0.80rem;
  --text-base:  1.00rem;
  --text-md:    1.25rem;
  --text-lg:    1.563rem;
  --text-xl:    1.953rem;
  --text-2xl:   2.441rem;

  /* Line heights */
  --leading-tight: 1.35;
  --leading-prose: 1.9;
  --leading-loose: 2.2;

  /* Letter spacing */
  --tracking-heading: 0.08em;
  --tracking-nav:     0.12em;
  --tracking-en:      0.01em;

  /* Spacing (8pt grid) */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Layout */
  --content-width:      680px;
  --content-width-wide: 960px;
  --nav-height:         60px;
}

/* ---------------------------------------------------------------
   2. Reset
--------------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-base);
  font-size: var(--text-base);
  line-height: var(--leading-prose);
  color: var(--color-ink);
  background-color: var(--color-paper);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, svg { display: block; max-width: 100%; }
ul, ol { list-style: none; }
button { cursor: pointer; font-family: inherit; }

/* ---------------------------------------------------------------
   3. Typography
--------------------------------------------------------------- */
h1, h2, h3, h4 {
  font-family: var(--font-base);
  font-weight: 600;
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

h1 {
  font-size: var(--text-xl);
  margin-bottom: var(--space-6);
}

h2 {
  font-size: var(--text-lg);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-paper-rule);
}

h3 {
  font-size: var(--text-md);
  margin-bottom: var(--space-3);
}

p {
  margin-bottom: var(--space-4);
  line-height: var(--leading-prose);
}

/* English text uses EB Garamond */
:lang(en), [lang="en"] {
  font-family: var(--font-serif-en);
  letter-spacing: var(--tracking-en);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}

a:hover {
  color: var(--color-accent-hover);
  border-bottom-color: var(--color-accent-hover);
}

blockquote {
  border-left: 3px solid var(--color-indigo);
  padding: var(--space-4) var(--space-6);
  margin: var(--space-8) 0;
  color: var(--color-ink-secondary);
  font-style: italic;
  background-color: var(--color-paper-dark);
}

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

hr {
  border: none;
  border-top: 1px solid var(--color-paper-rule);
  margin: var(--space-12) 0;
}

/* ---------------------------------------------------------------
   4. Layout Containers
--------------------------------------------------------------- */
.site-wrapper { flex: 1; }

.container {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container--wide {
  max-width: var(--content-width-wide);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

/* ---------------------------------------------------------------
   5. Navigation
--------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-paper-dark);
  border-bottom: 1px solid var(--color-paper-rule);
  height: var(--nav-height);
  display: flex;
  align-items: center;
}

.site-nav {
  display: flex;
  align-items: center;
  height: 100%;
  gap: var(--space-6);
}

.site-nav__identity {
  text-decoration: none;
  border-bottom: none;
  display: flex;
  flex-direction: column;
  justify-content: center;
  line-height: 1.2;
  margin-right: auto;
  flex-shrink: 0;
  gap: 2px;
}

.site-nav__identity:hover .site-nav__name-zh {
  color: var(--color-accent);
}

.site-nav__name-zh {
  font-size: var(--text-md);
  font-weight: 600;
  color: var(--color-ink);
  letter-spacing: 0.15em;
  transition: color 0.15s;
}

.site-nav__name-en {
  font-family: var(--font-serif-en);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.08em;
}

.site-nav__links {
  display: flex;
  gap: var(--space-6);
  align-items: center;
}

.nav-link {
  font-size: var(--text-sm);
  color: var(--color-ink-secondary);
  letter-spacing: var(--tracking-nav);
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: color 0.15s, border-color 0.15s;
}

.nav-link:hover,
.nav-link[aria-current="page"] {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* Language toggle button */
.lang-toggle {
  background: none;
  border: 1px solid var(--color-paper-rule);
  border-radius: 2px;
  padding: var(--space-1) var(--space-3);
  font-family: var(--font-base);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.06em;
  transition: border-color 0.15s, color 0.15s;
  white-space: nowrap;
  flex-shrink: 0;
}

.lang-toggle:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.lang-toggle[aria-pressed="true"] {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ---------------------------------------------------------------
   6. Footer
--------------------------------------------------------------- */
.site-footer {
  background-color: var(--color-paper-dark);
  border-top: 1px solid var(--color-paper-rule);
  padding: var(--space-8) 0;
  margin-top: var(--space-20);
}

.site-footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-4);
}

.site-footer__credit,
.site-footer__contact {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.04em;
}

.site-footer__contact a {
  color: var(--color-ink-muted);
  border-bottom-color: transparent;
}

.site-footer__contact a:hover {
  color: var(--color-accent);
}

/* ---------------------------------------------------------------
   7. Page Title Block (共用)
--------------------------------------------------------------- */
.page-title-block {
  padding-top: var(--space-16);
  padding-bottom: var(--space-8);
  border-bottom: 1px solid var(--color-paper-rule);
  margin-bottom: var(--space-12);
}

.page-title {
  font-size: var(--text-xl);
  letter-spacing: 0.1em;
  margin-bottom: var(--space-2);
  border-bottom: none;
}

.page-subtitle {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  letter-spacing: 0.08em;
  margin-bottom: 0;
}

/* ---------------------------------------------------------------
   8. Bilingual: Language Switching
--------------------------------------------------------------- */
/* Default: Chinese visible, English hidden */
.en { display: none; }
.zh { display: inline; }

p.en { display: none; }
p.zh { display: block; }

li.en { display: none; }
li.zh { display: list-item; }

/* When English active */
html.lang-en .en { display: inline; }
html.lang-en .zh { display: none; }

html.lang-en p.en { display: block; }
html.lang-en p.zh { display: none; }

html.lang-en li.en { display: list-item; }
html.lang-en li.zh { display: none; }

/* ---------------------------------------------------------------
   9. Prose Column
--------------------------------------------------------------- */
.prose {
  padding-top: var(--space-8);
  padding-bottom: var(--space-20);
}

.prose p {
  margin-bottom: var(--space-6);
  line-height: var(--leading-loose);
}

.prose ul, .prose ol {
  padding-left: var(--space-6);
  margin-bottom: var(--space-6);
}

.prose li {
  margin-bottom: var(--space-2);
  line-height: var(--leading-prose);
  list-style: disc;
}

/* ---------------------------------------------------------------
   10. Text Link (→ style links)
--------------------------------------------------------------- */
.text-link {
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  color: var(--color-ink-secondary);
  border-bottom: 1px solid var(--color-paper-rule);
  transition: color 0.15s, border-color 0.15s;
}

.text-link:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* ---------------------------------------------------------------
   11. Post List (首页预览 + 随笔索引共用)
--------------------------------------------------------------- */
.post-list {
  margin: var(--space-6) 0;
}

.post-list__item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: var(--space-4);
  padding: var(--space-5) 0;
  border-bottom: 1px solid var(--color-paper-rule);
  align-items: baseline;
}

.post-list__date {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.04em;
  padding-top: 3px;
}

.post-list__body {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.post-list__title {
  font-size: var(--text-base);
  color: var(--color-ink);
  border-bottom: none;
  line-height: var(--leading-tight);
  font-weight: 500;
}

.post-list__title:hover {
  color: var(--color-accent);
}

.post-list__excerpt {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  line-height: 1.6;
  margin-bottom: 0;
}

/* ---------------------------------------------------------------
   12. Home Page
--------------------------------------------------------------- */
.home-hero {
  padding: var(--space-24) 0 var(--space-16);
  text-align: center;
  border-bottom: 1px solid var(--color-paper-rule);
}

.home-hero__seal {
  font-size: 4rem;
  color: var(--color-ink);
  letter-spacing: 0;
  margin-bottom: var(--space-8);
  font-weight: 700;
  opacity: 0.08;
  line-height: 1;
  user-select: none;
}

.home-hero__name {
  font-size: var(--text-2xl);
  letter-spacing: 0.2em;
  margin-bottom: var(--space-3);
  border-bottom: none;
}

.home-hero__title {
  font-size: var(--text-base);
  color: var(--color-ink-secondary);
  letter-spacing: 0.2em;
  margin-bottom: var(--space-8);
  line-height: var(--leading-tight);
}

.home-hero__tagline {
  font-size: var(--text-md);
  color: var(--color-ink-secondary);
  line-height: var(--leading-loose);
  max-width: 520px;
  margin: 0 auto;
}

.home-intro {
  padding: var(--space-16) 0;
  border-bottom: 1px solid var(--color-paper-rule);
}

.home-intro__links {
  display: flex;
  gap: var(--space-8);
  margin-top: var(--space-8);
}

.home-recent {
  padding: var(--space-12) 0 var(--space-16);
}

.home-recent__more {
  margin-top: var(--space-6);
}

/* ---------------------------------------------------------------
   13. About Page
--------------------------------------------------------------- */
.about-portrait {
  float: right;
  margin: 0 0 var(--space-8) var(--space-8);
}

.about-portrait img {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  object-fit: cover;
  filter: grayscale(15%) sepia(8%);
  border: 3px solid var(--color-paper-rule);
}

.about-section {
  margin-bottom: var(--space-12);
}

.about-section ul {
  padding-left: var(--space-6);
}

.about-section li {
  list-style: disc;
  margin-bottom: var(--space-3);
  line-height: var(--leading-prose);
}

/* ---------------------------------------------------------------
   14. Publications Page
--------------------------------------------------------------- */
.pub-section {
  margin-bottom: var(--space-16);
}

.pub-list {
  margin-top: var(--space-6);
  list-style: none;
  padding-left: 0;
}

.pub-list li,
.pub-item {
  list-style: none !important;
  padding: var(--space-6) 0;
  border-bottom: 1px solid var(--color-paper-rule);
}

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

.pub-item__title {
  font-size: var(--text-base);
  font-weight: 500;
  margin-bottom: var(--space-1);
  line-height: var(--leading-tight);
}

.pub-item__title.en {
  font-style: italic;
  font-weight: 400;
}

.pub-item__meta {
  font-size: var(--text-sm);
  color: var(--color-ink-secondary);
  margin-bottom: var(--space-2);
  line-height: 1.6;
}

.pub-item__links {
  margin-top: var(--space-2);
}

.pub-link {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  border-bottom: 1px dotted var(--color-paper-rule);
  letter-spacing: 0.04em;
  margin-right: var(--space-4);
}

.pub-link:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* ---------------------------------------------------------------
   15. Medici Project Page
--------------------------------------------------------------- */
.medici-section {
  margin-bottom: var(--space-12);
}

.medici-intro {
  font-size: var(--text-md);
  color: var(--color-ink-secondary);
  line-height: var(--leading-loose);
  margin-bottom: var(--space-8);
  padding-bottom: var(--space-8);
  border-bottom: 1px solid var(--color-paper-rule);
}

/* ---------------------------------------------------------------
   16. Blog Index
--------------------------------------------------------------- */
.blog-year-group {
  margin-bottom: var(--space-4);
}

.blog-year-heading {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  letter-spacing: 0.2em;
  border-bottom: none;
  padding-bottom: 0;
  margin-bottom: var(--space-4);
  margin-top: var(--space-12);
}

.blog-year-group:first-of-type .blog-year-heading {
  margin-top: 0;
}

/* ---------------------------------------------------------------
   17. Blog Post
--------------------------------------------------------------- */
.blog-post {
  padding-top: var(--space-16);
  padding-bottom: var(--space-24);
}

.blog-post__header {
  margin-bottom: var(--space-12);
  padding-bottom: var(--space-8);
  border-bottom: 1px solid var(--color-paper-rule);
}

.blog-post__title {
  font-size: var(--text-xl);
  line-height: var(--leading-tight);
  letter-spacing: 0.06em;
  border-bottom: none;
  margin-bottom: var(--space-4);
}

.blog-post__meta {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.06em;
}

.blog-post__body {
  max-width: 640px;
}

.blog-post__footer {
  margin-top: var(--space-16);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-paper-rule);
}

/* ---------------------------------------------------------------
   18. Responsive
--------------------------------------------------------------- */
@media (max-width: 768px) {
  :root {
    --text-2xl: 1.953rem;
    --text-xl:  1.563rem;
  }

  .site-nav {
    gap: var(--space-3);
  }

  .site-nav__links {
    gap: var(--space-3);
  }

  .nav-link {
    font-size: 0.72rem;
    letter-spacing: 0.08em;
  }

  .home-hero {
    padding: var(--space-16) 0 var(--space-12);
  }

  .home-intro__links {
    flex-direction: column;
    gap: var(--space-4);
  }

  .about-portrait {
    float: none;
    margin: 0 auto var(--space-8);
    display: flex;
    justify-content: center;
  }

  .post-list__item {
    grid-template-columns: 1fr;
    gap: var(--space-1);
  }

  .post-list__date {
    padding-top: 0;
  }
}

@media (max-width: 480px) {
  .site-nav__name-en {
    display: none;
  }

  .site-nav__links {
    gap: var(--space-2);
  }

  .nav-link {
    font-size: 0.68rem;
  }

  .home-hero__seal {
    font-size: 3rem;
  }

  .container {
    padding: 0 var(--space-4);
  }
}