/* ============================================================
   CSS Custom Properties — Light & Dark Themes
   ============================================================ */
:root,
[data-theme="light"] {
  --color-bg:           #ffffff;
  --color-bg-secondary: #f7f7f5;
  --color-surface:      #f0efeb;
  --color-border:       #e2e2df;
  --color-text:         #1a1a18;
  --color-text-muted:   #6b6b67;
  --color-text-faint:   #9b9b97;
  --color-accent:       #0f7c5a;
  --color-accent-hover: #0a5e44;
  --color-link:         #0f7c5a;
  --color-code-bg:      #f4f4f1;
  --color-code-text:    #2d2d2b;
  --color-blockquote:   #e8f5f0;
  --color-blockquote-border: #0f7c5a;
  --shadow-card:        0 1px 3px rgba(0,0,0,0.08);
  --shadow-card-hover:  0 4px 12px rgba(0,0,0,0.12);
}

[data-theme="dark"] {
  --color-bg:           #141413;
  --color-bg-secondary: #1c1c1a;
  --color-surface:      #242422;
  --color-border:       #333331;
  --color-text:         #e8e8e4;
  --color-text-muted:   #9b9b97;
  --color-text-faint:   #6b6b67;
  --color-accent:       #3dd68c;
  --color-accent-hover: #5ee8a4;
  --color-link:         #3dd68c;
  --color-code-bg:      #1e1e1c;
  --color-code-text:    #d4d4d0;
  --color-blockquote:   #1a2e24;
  --color-blockquote-border: #3dd68c;
  --shadow-card:        0 1px 3px rgba(0,0,0,0.3);
  --shadow-card-hover:  0 4px 12px rgba(0,0,0,0.4);
}

/* ============================================================
   Reset & Base
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  transition: background-color 0.2s ease, color 0.2s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

#main-content { flex: 1; }

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--color-link);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

/* ============================================================
   Typography
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-text);
  line-height: 1.25;
  font-weight: 700;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h2 { font-size: clamp(1.35rem, 3vw, 1.875rem); border-bottom: 1px solid var(--color-border); padding-bottom: 0.4rem; }
h3 { font-size: clamp(1.1rem, 2.5vw, 1.375rem); }
h4 { font-size: 1.1rem; }

p  { margin-bottom: 1.25rem; }
ul, ol { margin-bottom: 1.25rem; padding-left: 1.5rem; }
li { margin-bottom: 0.4rem; }

strong { font-weight: 600; }
em     { font-style: italic; }

blockquote {
  background: var(--color-blockquote);
  border-left: 4px solid var(--color-blockquote-border);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  border-radius: 0 6px 6px 0;
  color: var(--color-text-muted);
  font-style: italic;
}
blockquote p:last-child { margin-bottom: 0; }

hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0;
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
  overflow-x: auto;
  display: block;
}
th, td {
  padding: 0.6rem 1rem;
  border: 1px solid var(--color-border);
  text-align: left;
}
th {
  background: var(--color-surface);
  font-weight: 600;
}
tr:nth-child(even) { background: var(--color-bg-secondary); }

/* Code */
code {
  font-family: "SF Mono", "Fira Code", "Consolas", monospace;
  font-size: 0.875em;
  background: var(--color-code-bg);
  color: var(--color-code-text);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}

pre {
  background: var(--color-code-bg);
  color: var(--color-code-text);
  padding: 1.25rem 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  line-height: 1.6;
  border: 1px solid var(--color-border);
}
pre code {
  background: none;
  padding: 0;
  font-size: 0.875rem;
  border-radius: 0;
}

/* ============================================================
   Layout Containers
   ============================================================ */
.header-inner,
.footer-inner,
.post-container,
.series-container,
.home-container,
.search-container {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* ============================================================
   Header
   ============================================================ */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}
.header-inner {
  max-width: 960px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  gap: 1rem;
}

.site-logo {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  white-space: nowrap;
}
.site-logo:hover { text-decoration: none; color: var(--color-accent); }
.logo-dot { color: var(--color-accent); }

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}
.nav-link {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  padding: 0.35rem 0.7rem;
  border-radius: 6px;
  text-decoration: none;
  transition: color 0.15s, background 0.15s;
  white-space: nowrap;
}
.nav-link:hover,
.nav-link--active {
  color: var(--color-text);
  background: var(--color-surface);
  text-decoration: none;
}

.header-actions { display: flex; align-items: center; }

.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 0.35rem 0.6rem;
  cursor: pointer;
  color: var(--color-text-muted);
  font-size: 1rem;
  line-height: 1;
  transition: border-color 0.15s, color 0.15s;
}
.theme-toggle:hover { border-color: var(--color-text-muted); color: var(--color-text); }

[data-theme="light"] .theme-icon--dark,
[data-theme="dark"]  .theme-icon--light { display: none; }

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  margin-top: 4rem;
}
.footer-inner {
  max-width: 960px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  text-align: center;
}
.footer-links {
  display: flex;
  gap: 1.5rem;
}
.footer-links a {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}
.footer-links a:hover { color: var(--color-accent); }
.footer-copy {
  font-size: 0.8rem;
  color: var(--color-text-faint);
  margin: 0;
}

/* ============================================================
   Post Layout
   ============================================================ */
.post-container {
  padding-top: 3rem;
  padding-bottom: 4rem;
}

.post-series-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}
.post-series-label a { color: var(--color-accent); text-decoration: none; }
.post-series-label a:hover { text-decoration: underline; }

.post-title {
  margin-top: 0;
  margin-bottom: 0.75rem;
}

.post-description {
  font-size: 1.15rem;
  color: var(--color-text-muted);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.post-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.875rem;
  color: var(--color-text-faint);
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.post-hero-image {
  width: 100%;
  border-radius: 10px;
  margin-bottom: 2.5rem;
  object-fit: cover;
  max-height: 480px;
}

.post-content {
  font-size: 1.05rem;
  line-height: 1.8;
}
.post-content > *:first-child { margin-top: 0; }

.post-footer {
  margin-top: 3.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* ============================================================
   Share Buttons
   ============================================================ */
.share-section { }
.share-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
  margin-bottom: 0.6rem;
}
.share-buttons {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.share-btn {
  display: inline-block;
  padding: 0.45rem 1rem;
  border-radius: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: opacity 0.15s;
  border: 1px solid transparent;
}
.share-btn:hover { opacity: 0.85; text-decoration: none; }
.share-btn--linkedin { background: #0077b5; color: #fff; }
.share-btn--twitter  { background: #1a1a1a; color: #fff; }
.share-btn--copy     { background: var(--color-surface); color: var(--color-text); border-color: var(--color-border); }

/* ============================================================
   Series Navigation
   ============================================================ */
.series-nav { }
.series-nav-home {
  display: inline-block;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 1rem;
  text-decoration: none;
}
.series-nav-home:hover { color: var(--color-accent); text-decoration: none; }

.series-nav-links {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}
.series-nav-link {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.85rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  text-decoration: none;
  transition: border-color 0.15s, box-shadow 0.15s;
  background: var(--color-bg);
}
.series-nav-link:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-card);
  text-decoration: none;
}
.series-nav-link--prev { grid-column: 1; }
.series-nav-link--next { grid-column: 2; text-align: right; }

.series-nav-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
}
.series-nav-title {
  font-size: 0.9rem;
  color: var(--color-text);
  font-weight: 500;
  line-height: 1.3;
}

/* ============================================================
   Series Landing Page
   ============================================================ */
.series-container {
  padding-top: 3rem;
  padding-bottom: 4rem;
}

.series-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
  margin-bottom: 0.5rem;
}

.series-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  margin-top: 0;
  margin-bottom: 0.75rem;
}

.series-description {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.series-meta {
  font-size: 0.875rem;
  color: var(--color-text-faint);
  margin-bottom: 2.5rem;
}

.series-post-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.series-post-item { margin: 0; }

.series-post-link {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  text-decoration: none;
  background: var(--color-bg);
  transition: border-color 0.15s, box-shadow 0.15s, background 0.15s;
}
.series-post-link:hover {
  border-color: var(--color-accent);
  background: var(--color-bg-secondary);
  box-shadow: var(--shadow-card);
  text-decoration: none;
}

.series-post-number {
  flex-shrink: 0;
  width: 2rem;
  height: 2rem;
  background: var(--color-surface);
  color: var(--color-text-muted);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 600;
  margin-top: 0.1rem;
}

.series-post-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.series-post-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.3;
}

.series-post-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.4;
}

.series-post-audience {
  font-size: 0.775rem;
  color: var(--color-text-faint);
  font-weight: 500;
}

/* ============================================================
   Home Page
   ============================================================ */
.home-container {
  padding-top: 3rem;
  padding-bottom: 4rem;
}

.home-header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--color-border);
}

.home-title {
  font-size: clamp(2rem, 5vw, 3rem);
  margin-top: 0;
  margin-bottom: 0.5rem;
}

.home-subtitle {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  margin: 0;
}

.section-title {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
  margin-top: 0;
  margin-bottom: 1rem;
  border-bottom: none;
  padding-bottom: 0;
}

.series-section { margin-bottom: 3rem; }

.series-grid {
  display: grid;
  gap: 1rem;
}

.series-card {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  text-decoration: none;
  background: var(--color-bg-secondary);
  transition: border-color 0.15s, box-shadow 0.15s;
}
.series-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-card-hover);
  text-decoration: none;
}

.series-card-label {
  font-size: 0.775rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-accent);
}

.series-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 0;
}

.series-card-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.5;
  margin: 0;
}

.series-card-cta {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-top: 0.5rem;
}

.recent-section { }

.post-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.post-card {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  text-decoration: none;
  background: var(--color-bg);
  transition: border-color 0.15s, box-shadow 0.15s;
}
.post-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-card);
  text-decoration: none;
}

.post-card-meta {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  font-size: 0.775rem;
  color: var(--color-text-faint);
}

.post-card-series {
  font-weight: 600;
  color: var(--color-accent);
  font-size: 0.775rem;
}

.post-card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.3;
  margin: 0;
}

.post-card-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.4;
  margin: 0;
}

/* ============================================================
   Search Page
   ============================================================ */
.search-container {
  padding-top: 3rem;
  padding-bottom: 4rem;
}

.search-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin-top: 0;
  margin-bottom: 1.5rem;
}

.search-form {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

#search-input {
  flex: 1;
  padding: 0.7rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-bg);
  color: var(--color-text);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.15s;
}
#search-input:focus { border-color: var(--color-accent); }
#search-input::placeholder { color: var(--color-text-faint); }

.search-results { display: flex; flex-direction: column; gap: 0.5rem; }

.search-result-item {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  text-decoration: none;
  background: var(--color-bg);
  transition: border-color 0.15s;
}
.search-result-item:hover {
  border-color: var(--color-accent);
  text-decoration: none;
}

.search-result-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
}
.search-result-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}
.search-no-results {
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 640px) {
  .header-inner { height: 52px; }

  .site-nav .nav-link:not(.nav-link--active) { display: none; }
  .site-nav .nav-link:last-child { display: inline-block; }

  .series-nav-links { grid-template-columns: 1fr; }
  .series-nav-link--next { grid-column: 1; text-align: left; }

  .post-meta { flex-direction: column; gap: 0.25rem; }

  .share-buttons { flex-direction: column; }
  .share-btn { text-align: center; }

  .series-post-link { flex-direction: column; gap: 0.5rem; }
}

@media (min-width: 641px) and (max-width: 900px) {
  .site-nav .nav-link { font-size: 0.85rem; padding: 0.3rem 0.5rem; }
}

/* ============================================================
   Utility
   ============================================================ */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

/* Print */
@media print {
  .site-header, .site-footer, .share-section, .series-nav, .theme-toggle { display: none; }
  body { color: #000; background: #fff; }
  a { color: #000; }
}

/* ============================================================
   Tag Chips — used on posts and tags page
   ============================================================ */
.tag-chip {
  display: inline-block;
  padding: 0.25rem 0.65rem;
  background: var(--color-surface);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  font-size: 0.775rem;
  font-weight: 500;
  text-decoration: none;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
  white-space: nowrap;
}
.tag-chip:hover {
  background: var(--color-accent);
  color: var(--color-bg);
  border-color: var(--color-accent);
  text-decoration: none;
}
.tag-chip--heading {
  font-size: 0.9rem;
  padding: 0.3rem 0.85rem;
}

/* Tag row on post header */
.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
  margin-bottom: 0.25rem;
}

/* ============================================================
   Tags Page
   ============================================================ */
.tags-container {
  max-width: 760px;
  margin: 0 auto;
  padding: 3rem 1.25rem 4rem;
}

.tags-header {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.tags-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  margin-top: 0;
  margin-bottom: 0.4rem;
}

.tags-subtitle {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0;
}

/* Jump list — all tags at top for quick navigation */
.tag-jump-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 3rem;
  padding: 1.25rem;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 10px;
}

.tag-jump {
  display: inline-block;
  padding: 0.3rem 0.75rem;
  background: var(--color-bg);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 500;
  text-decoration: none;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}
.tag-jump:hover {
  background: var(--color-accent);
  color: var(--color-bg);
  border-color: var(--color-accent);
  text-decoration: none;
}

/* Each tag section */
.tag-section {
  margin-bottom: 2.5rem;
  scroll-margin-top: 72px;
}

.tag-section-title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1rem;
  margin-top: 0;
  margin-bottom: 1rem;
  border-bottom: none;
  padding-bottom: 0;
}

.tag-section-count {
  font-size: 0.8rem;
  color: var(--color-text-faint);
  font-weight: 400;
}

.tag-post-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.tag-post-item { margin: 0; }

.tag-post-link {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  text-decoration: none;
  background: var(--color-bg);
  transition: border-color 0.15s, background 0.15s;
}
.tag-post-link:hover {
  border-color: var(--color-accent);
  background: var(--color-bg-secondary);
  text-decoration: none;
}

.tag-post-title {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.4;
}

.tag-post-meta {
  font-size: 0.775rem;
  color: var(--color-text-faint);
  white-space: nowrap;
  flex-shrink: 0;
}

/* Inline post images */
.post-inline-image {
  border-radius: 8px;
  margin: 1.75rem 0;
  width: 100%;
  height: auto;
}

@media (max-width: 640px) {
  .tag-post-link { flex-direction: column; gap: 0.2rem; }
  .tag-post-meta { align-self: flex-start; }
}