:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-accent: #1d4ed8;
  --color-muted: #6b7280;
  --color-border: #e5e7eb;
  --max-width: 720px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

*, *::before, *::after {
  box-sizing: border-box;
}

body {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  margin: 0;
  padding: 0;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.skip-link:focus {
  position: static;
  width: auto;
  height: auto;
  display: block;
  padding: 0.5rem 1rem;
  background: var(--color-accent);
  color: #fff;
  text-decoration: none;
}

/* Header */
header {
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 1.5rem;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.site-branding {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}

.site-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
}

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

.site-tagline {
  font-size: 0.8125rem;
  color: var(--color-muted);
  margin: 0;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}

nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.9375rem;
}

nav a:hover,
nav a[aria-current="page"] {
  color: var(--color-accent);
  text-decoration: underline;
}

/* Main content */
main {
  max-width: var(--max-width);
  margin: 2.5rem auto;
  padding: 0 1.5rem;
}

/* Footer */
footer {
  border-top: 1px solid var(--color-border);
  padding: 1.5rem;
  text-align: center;
  color: var(--color-muted);
  font-size: 0.875rem;
  margin-top: 3rem;
}

.footer-social {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 0.75rem;
}

.footer-social a {
  color: var(--color-muted);
  text-decoration: none;
}

.footer-social a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

/* Typography */
h1 {
  font-size: 2rem;
  line-height: 1.25;
  margin-top: 0;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.4rem;
  margin-top: 2rem;
  margin-bottom: 0.5rem;
}

h3 {
  font-size: 1.15rem;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
}

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

a:hover {
  text-decoration: underline;
}

/* Home intro */
.intro {
  margin-bottom: 2.5rem;
}

.intro h1 {
  margin-bottom: 0.75rem;
}

/* Post list on home page */
.post-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.post-list li {
  border-top: 1px solid var(--color-border);
  padding: 1.25rem 0;
}

.post-list li:last-child {
  border-bottom: 1px solid var(--color-border);
}

.post-list .post-meta {
  color: var(--color-muted);
  font-size: 0.875rem;
  margin: 0 0 0.25rem;
}

.post-list .post-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 0.5rem;
}

.post-list .post-excerpt {
  margin: 0;
  color: #374151;
}

/* Post page */
.post-header {
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border);
}

.post-header h1 {
  margin-bottom: 0.25rem;
}

.post-date {
  color: var(--color-muted);
  font-size: 0.9375rem;
  margin: 0;
}

.post-content h2 {
  margin-top: 2rem;
}

/* Responsive */
@media (max-width: 600px) {
  h1 {
    font-size: 1.6rem;
  }

  .header-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}