/* ==========================================================================
   Modern HTML Base Stylesheet
   ========================================================================== */

/* 1. CSS Custom Properties (Theme Setup) */
:root {
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
  
  /* Light Theme Colors */
  --bg-color: #fcfcfc;
  --text-color: #212529;
  --heading-color: #0f172a;
  --accent-color: #2563eb;
  --border-color: #e2e8f0;
  --code-bg: #f1f5f9;
  --quote-border: #3b82f6;
}

/* Dark Theme Support (Automatic based on user system preference) */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #0f172a;
    --text-color: #cbd5e1;
    --heading-color: #f8fafc;
    --accent-color: #60a5fa;
    --border-color: #334155;
    --code-bg: #1e293b;
    --quote-border: #60a5fa;
  }
}


body.dark-mode {
  --bg-color: #0f172a;
  --text-color: #cbd5e1;
  --primary-color: #60a5fa;
  --border-color: #334155;
  --code-bg: #1e293b;
}

/* 2. Page & Layout Defaults */
*, *::before, *::after {
  box-sizing: border-box;
}

body {
  font-family: var(--font-sans);
  font-size: 1.125rem; /* 18px base for optimal readability */
  line-height: 1.7;
  color: var(--text-color);
  background-color: var(--bg-color);
  max-width: 70ch; /* ~70 characters per line for ideal reading length */
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem 1.5rem;
}

/* 3. Typography */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.25;
  margin-top: 2rem;
  margin-bottom: 1rem;
  font-weight: 700;
  color: var(--text-color); /* Ensures headings shift to white/slate in dark mode */

}

h1 { font-size: 2.25rem; margin-top: 1em; }
h2 { font-size: 1.75rem; }
h3 { font-size: 1.35rem; }

p {
  margin-top: 0;
  margin-bottom: 1.5rem;
}

a {
  color: var(--accent-color);
  text-decoration-skip-ink: auto;
}

a:hover {
  text-decoration: none;
}

/* 4. Lists & Blockquotes */
ul, ol {
  padding-left: 1.5rem;
  margin-bottom: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
}

blockquote {
  margin: 1.5rem 0;
  padding: 0.5rem 1rem 0.5rem 1.25rem;
  border-left: 4px solid var(--quote-border);
  background: var(--code-bg);
  font-style: italic;
}

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

/* 5. Code & Media Elements */
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--code-bg);
  padding: 0.2em 0.4em;
  border-radius: 4px;
}

pre {
  background-color: var(--code-bg);
  padding: 1rem;
  overflow-x: auto;
  border-radius: 6px;
  margin-bottom: 1.5rem;
}

pre code {
  padding: 0;
  background: none;
}

img, video, iframe {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  margin: 1.5rem 0;
}

hr {
  border: 0;
  border-top: 1px solid var(--border-color);
  margin: 3rem 0;
}

/* 6. Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5rem;
}

th, td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

th {
  color: var(--heading-color);
  font-weight: 600;
}