/* ===== THEME VARIABLES ===== */
:root {
  --bg: #111118;
  --bg-surface: #1c1c28;
  --bg-hover: #25253a;
  --border: #2d2d45;
  --accent: #8b7cf8;
  --accent-hover: #a594ff;
  --text: #e8e8f2;
  --text-muted: #8888aa;
  --code-bg: #161622;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
  --radius: 8px;
  --transition: 0.2s ease;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Cascadia Code", "Consolas", monospace;
}

[data-theme="light"] {
  --bg: #f5f5fa;
  --bg-surface: #ffffff;
  --bg-hover: #ebebf5;
  --border: #dddded;
  --accent: #6254d4;
  --accent-hover: #7b6ee8;
  --text: #1a1a2e;
  --text-muted: #666688;
  --code-bg: #eeeef8;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

[data-theme="darker"] {
  --bg: #000000;
  --bg-surface: #000000;
  --bg-hover: #000000;
  --border: #000000;
  --accent: #000000;
  --text: #000000;
  --text-muted: #000000;
  --code-bg: #000000;
  --shadow: none;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background var(--transition), color var(--transition);
}

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

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

img {
  max-width: 100%;
}

/* ===== LAYOUT ===== */
.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== HEADER ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  transition: background var(--transition), border-color var(--transition);
}

.header-inner {
  max-width: 860px;
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
  white-space: nowrap;
  transition: color var(--transition);
}

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

.header-right {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.site-nav {
  display: flex;
  gap: 1.5rem;
  transition: opacity var(--transition);
}

.site-nav a {
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--text);
}

/* ===== THEME CONTROLS ===== */
.theme-controls {
  display: flex;
  gap: 0.4rem;
  align-items: center;
  position: relative;
  z-index: 200;
}

.theme-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.3rem 0.7rem;
  border-radius: var(--radius);
  font-size: 0.78rem;
  font-family: var(--font-sans);
  font-weight: 500;
  line-height: 1.5;
  transition: background var(--transition), border-color var(--transition), color var(--transition);
}

.theme-btn:hover {
  background: var(--bg-hover);
  border-color: var(--accent);
  color: var(--text);
}

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

/* ===== DARKER MODE ===== */
[data-theme="darker"] body {
  background: #000;
}

[data-theme="darker"] .site-header {
  background: #000;
  border-color: #000;
}

[data-theme="darker"] .site-title,
[data-theme="darker"] .site-nav {
  opacity: 0;
  pointer-events: none;
}

[data-theme="darker"] .site-content,
[data-theme="darker"] .site-footer {
  opacity: 0;
  pointer-events: none;
}

[data-theme="darker"] .theme-btn {
  background: #1c1c1c;
  border-color: #444;
  color: #bbb;
  opacity: 1;
}

[data-theme="darker"] .theme-btn:hover {
  border-color: #888;
  color: #fff;
  background: #2a2a2a;
}

[data-theme="darker"] #darker-btn {
  background: #2a2a2a;
  border-color: #777;
  color: #eee;
}

/* ===== MAIN ===== */
.site-content {
  flex: 1;
  padding: 3rem 0;
  transition: opacity var(--transition);
}

/* ===== HERO ===== */
.hero {
  padding: 4rem 0 3.5rem;
}

.hero-eyebrow {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
}

.hero h1 {
  font-size: 2.6rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.15;
  margin-bottom: 1.25rem;
}

.hero h1 span {
  color: var(--accent);
}

.hero p {
  font-size: 1.05rem;
  color: var(--text-muted);
  max-width: 540px;
  margin-bottom: 2rem;
  line-height: 1.8;
}

.hero-cta {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-block;
  padding: 0.6rem 1.3rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  border: 1px solid transparent;
  transition: all var(--transition);
  cursor: pointer;
}

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

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

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border-color: var(--border);
}

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

/* ===== SECTION HEADING ===== */
.section-heading {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-heading::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* ===== POST CARDS ===== */
.post-grid {
  display: grid;
  gap: 1rem;
}

.post-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem 1.5rem;
  transition: border-color var(--transition), transform 0.15s ease, box-shadow 0.15s ease;
}

.post-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.post-card-link {
  display: block;
  color: inherit;
  text-decoration: none;
}

.post-card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 0.5rem;
}

.post-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
  transition: color var(--transition);
}

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

.post-date {
  font-size: 0.78rem;
  color: var(--text-muted);
  white-space: nowrap;
  flex-shrink: 0;
  margin-top: 0.15rem;
}

.post-excerpt {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.65;
  margin-bottom: 1rem;
}

/* ===== TAGS ===== */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  display: inline-block;
  padding: 0.18rem 0.6rem;
  border-radius: 99px;
  font-size: 0.72rem;
  font-weight: 600;
  background: var(--bg-hover);
  color: var(--text-muted);
  border: 1px solid var(--border);
  text-decoration: none;
  transition: all var(--transition);
  cursor: pointer;
  letter-spacing: 0.02em;
}

.tag:hover,
.tag.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* ===== TAG FILTER BAR ===== */
.tag-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  padding: 0.9rem 1.1rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 1.75rem;
}

.tag-filter-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-right: 0.25rem;
}

/* ===== PAGE HEADER ===== */
.page-header {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}

.page-header h1 {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.4rem;
}

.page-header p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* ===== BLOG POST ===== */
.post-header {
  padding: 3rem 0 2.5rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}

.post-header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 1.1rem;
}

.post-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.post-meta-divider {
  color: var(--border);
}

.post-body {
  font-size: 1.02rem;
  line-height: 1.85;
}

.post-body h2 {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 2.5rem 0 0.9rem;
  color: var(--text);
}

.post-body h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin: 2rem 0 0.7rem;
  color: var(--text);
}

.post-body p {
  margin-bottom: 1.4rem;
}

.post-body ul,
.post-body ol {
  margin: 0.5rem 0 1.4rem 1.5rem;
}

.post-body li {
  margin-bottom: 0.4rem;
}

.post-body strong {
  color: var(--text);
  font-weight: 600;
}

.post-body a {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.post-body blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.75rem 1.25rem;
  margin: 1.5rem 0;
  background: var(--bg-surface);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--text-muted);
  font-style: italic;
}

.post-body code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--code-bg);
  padding: 0.15em 0.45em;
  border-radius: 4px;
  border: 1px solid var(--border);
  color: var(--accent-hover);
}

.post-body pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.4rem;
  overflow-x: auto;
  margin: 1.5rem 0;
}

.post-body pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--text);
}

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

.post-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

.post-nav a {
  font-size: 0.875rem;
  font-weight: 500;
}

/* ===== ABOUT ===== */
.about-body {
  display: grid;
  gap: 3rem;
}

.about-intro p {
  font-size: 1.05rem;
  line-height: 1.85;
  margin-bottom: 1.2rem;
  color: var(--text-muted);
}

.about-intro p:first-child {
  font-size: 1.15rem;
  color: var(--text);
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 1rem;
}

.topic-card {
  display: block;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  text-decoration: none;
  color: inherit;
  transition: border-color var(--transition), transform 0.15s ease, box-shadow 0.15s ease;
}

.topic-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.topic-icon {
  font-size: 1.4rem;
  margin-bottom: 0.75rem;
  display: block;
}

.topic-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
  color: var(--text);
}

.topic-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ===== EMPTY STATE ===== */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* ===== FOOTER ===== */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.25rem 0;
  transition: opacity var(--transition);
}

.footer-inner {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  color: var(--text-muted);
  font-size: 0.8rem;
}

.footer-inner a {
  color: var(--text-muted);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.footer-inner a:hover {
  color: var(--accent);
}

.indented {
    text-indent: 2em;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.9rem; }
  .post-header h1 { font-size: 1.65rem; }
  .header-inner { padding: 0.75rem 1rem; }
  .container { padding: 0 1rem; }
  .header-right { gap: 1rem; }
  .site-nav { gap: 1rem; }
  .post-card-top { flex-direction: column; gap: 0.25rem; }
  .hero { padding: 2.5rem 0 2rem; }
  .site-content { padding: 2rem 0; }
  .topic-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 400px) {
  .site-nav { display: none; }
  .topic-grid { grid-template-columns: 1fr; }
}