/* ================================================================
   Base - CSS Reset, Custom Properties & Base Elements
   Theme: Quiet - A clean and quiet Halo 2 theme for long-form writing
   ================================================================ */

/* --- CSS Custom Properties --- */
:root {
  /* Colors - Light Mode */
  --color-bg:          #fafaf9;
  --color-bg-alt:      #f5f5f4;
  --color-bg-elevated: #ffffff;
  --color-text:        #1c1917;
  --color-text-secondary: #57534e;
  --color-text-muted:  #78716c;
  --color-border:      #e7e5e4;
  --color-border-hover:#d6d3d1;
  --color-accent:      #2563eb;
  --color-accent-hover:#1d4ed8;
  --color-accent-bg:   #eff6ff;
  --color-tag-bg:      #f5f5f4;
  --color-tag-text:    #57534e;
  --color-code-bg:     #f5f5f4;
  --color-shadow:      rgba(28, 25, 23, 0.06);
  --color-shadow-lg:   rgba(28, 25, 23, 0.10);

  /* Semantic: link underline (low-opacity accent) */
  --color-link-underline: rgba(37, 99, 235, 0.3);
  /* Semantic: success (copy-code, is-copied) */
  --color-success:        #16a34a;
  /* Semantic: warning (post-progress-notice) */
  --color-warning-text:   #b45309;
  --color-warning-bg:     #fef3c7;
  --color-warning-border: #fde68a;
  /* Semantic: highlight (mark) */
  --color-mark-bg:        #fef08a;
  --color-mark-text:      #1c1917;

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC',
               'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'SFMono-Regular',
               'Consolas', 'Liberation Mono', monospace;

  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;

  /* Radius */
  --radius-sm:  0.25rem;
  --radius-md:  0.5rem;
  --radius-lg:  0.75rem;
  --radius-xl:  1rem;
  --radius-full: 9999px;

  /* Layout */
  --container-width:      720px;
  --container-wide:       960px;
  --container-full:       1560px;
  --header-height:        64px;
}

/* --- Dark Mode Variables --- */
[data-theme="dark"] {
  --color-bg:          #0c0a09;
  --color-bg-alt:      #1c1917;
  --color-bg-elevated: #1c1917;
  --color-text:        #fafaf9;
  --color-text-secondary: #d6d3d1;
  --color-text-muted:  #a8a29e;
  --color-border:      #292524;
  --color-border-hover:#44403c;
  --color-accent:      #3b82f6;
  --color-accent-hover:#60a5fa;
  --color-accent-bg:   #0f172a;
  --color-tag-bg:      #292524;
  --color-tag-text:    #a8a29e;
  --color-code-bg:     #1c1917;
  --color-shadow:      rgba(0, 0, 0, 0.30);
  --color-shadow-lg:   rgba(0, 0, 0, 0.50);

  /* Semantic dark overrides */
  --color-link-underline:   rgba(96, 165, 250, 0.35);
  --color-success:          #4ade80;
  --color-warning-text:     #fbbf24;
  --color-warning-bg:       rgba(180, 83, 9, 0.18);
  --color-warning-border:   rgba(180, 83, 9, 0.4);
  --color-mark-bg:          #854d0e;
  --color-mark-text:        #fef08a;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  overflow-x: hidden;
}

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

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.15s ease;
}

button {
  font: inherit;
  color: inherit;
  background: none;
  border: none;
  cursor: pointer;
}

ul, ol {
  list-style: none;
}

hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-8) 0;
}

/* --- Base Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text);
  letter-spacing: -0.01em;
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
}

/* --- Selection --- */
::selection {
  background-color: var(--color-accent-bg);
  color: var(--color-accent);
}

/* --- Focus States --- */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* --- Scrollbar (webkit) --- */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background-color: var(--color-border);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background-color: var(--color-border-hover);
}

/* --- Transition for theme switch --- */
html[data-theme] body,
html[data-theme] body * {
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

/* --- Skip to content link (a11y) --- */
.skip-link {
  position: absolute;
  top: -100px;
  left: 8px;
  z-index: 9999;
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 500;
  text-decoration: none;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 8px;
  color: white;
  outline: 2px solid white;
  outline-offset: 2px;
}

/* --- Make main remove the focus outline since we used tabindex=-1 --- */
#site-main:focus {
  outline: none;
}

/* --- Reading progress bar (post page) --- */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-hover));
  z-index: 200;
  transition: width 0.1s linear;
  pointer-events: none;
}

/* --- Back to top button --- */
.back-to-top {
  position: fixed;
  right: var(--space-6);
  bottom: var(--space-6);
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-elevated);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  box-shadow: 0 4px 12px var(--color-shadow);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s, color 0.15s ease, border-color 0.15s ease;
  z-index: 50;
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

@media (max-width: 768px) {
  .back-to-top {
    right: var(--space-4);
    bottom: var(--space-4);
    width: 40px;
    height: 40px;
  }
}

/* --- Respect user's motion preferences (a11y) --- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}


/* --- Color Palette Presets ---
   Each palette overrides --color-accent / --color-accent-hover / --color-accent-bg
   and a soft variant for backgrounds. The data-palette attribute is set on
   <html> by modules/theme-tokens.html based on the theme appearance config.
   In light mode every palette honors the user's custom accent color via
   --data-custom-accent (falls back to the palette preset when unset).
   Dark mode always uses the preset so contrast on dark backgrounds is safe.
*/
:root[data-palette="blue"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #2563eb);
  --color-accent-hover: #1d4ed8;
  --color-accent-bg: #eff6ff;
}
:root[data-palette="blue"][data-theme="dark"] {
  --color-accent: #60a5fa;
  --color-accent-hover: #93c5fd;
  --color-accent-bg: #0f172a;
}

:root[data-palette="green"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #16a34a);
  --color-accent-hover: #15803d;
  --color-accent-bg: #f0fdf4;
}
:root[data-palette="green"][data-theme="dark"] {
  --color-accent: #4ade80;
  --color-accent-hover: #86efac;
  --color-accent-bg: #052e16;
}

:root[data-palette="orange"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #ea580c);
  --color-accent-hover: #c2410c;
  --color-accent-bg: #fff7ed;
}
:root[data-palette="orange"][data-theme="dark"] {
  --color-accent: #fb923c;
  --color-accent-hover: #fdba74;
  --color-accent-bg: #431407;
}

:root[data-palette="pink"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #db2777);
  --color-accent-hover: #be185d;
  --color-accent-bg: #fdf2f8;
}
:root[data-palette="pink"][data-theme="dark"] {
  --color-accent: #f472b6;
  --color-accent-hover: #f9a8d4;
  --color-accent-bg: #500724;
}

:root[data-palette="purple"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #7c3aed);
  --color-accent-hover: #6d28d9;
  --color-accent-bg: #f5f3ff;
}
:root[data-palette="purple"][data-theme="dark"] {
  --color-accent: #a78bfa;
  --color-accent-hover: #c4b5fd;
  --color-accent-bg: #2e1065;
}

:root[data-palette="black"][data-theme="light"] {
  --color-accent: var(--data-custom-accent, #0f172a);
  --color-accent-hover: #020617;
  --color-accent-bg: #f1f5f9;
}
:root[data-palette="black"][data-theme="dark"] {
  --color-accent: #e2e8f0;
  --color-accent-hover: #f8fafc;
  --color-accent-bg: #020617;
}

/* The data-custom-accent attribute is read via the CSS variable trick above.
   We need a fallback: when data-custom-accent is set on <html>, expose its
   value as a CSS custom property */
/* removed: attr() not valid for custom properties; use JS style.setProperty() */