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

:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-muted: #555555;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e5e7eb;
  --max-width: 820px;
}

body {
  font-family: system-ui, -apple-system, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  margin: 0;
  padding: 0;
  line-height: 1.7;
}

.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  background: var(--color-accent);
  color: white;
  padding: 0.5rem 1rem;
  text-decoration: none;
  z-index: 100;
}
.skip-link:focus {
  top: 0;
}

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

nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
}

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

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

nav ul a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.95rem;
}

nav ul a:hover,
nav ul a:focus {
  color: var(--color-accent);
  text-decoration: underline;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem 2rem;
}

footer {
  border-top: 1px solid var(--color-border);
  padding: 1.5rem 2rem;
  text-align: center;
  color: var(--color-muted);
  font-size: 0.9rem;
  margin-top: 4rem;
}

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

h1, h2, h3 {
  line-height: 1.3;
}
h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; margin-top: 2.5rem; }
h3 { font-size: 1.15rem; }

/* Hero */
.hero {
  display: flex;
  gap: 2.5rem;
  align-items: center;
  margin-bottom: 3rem;
}

.hero-image img {
  width: 180px;
  height: 180px;
  object-fit: cover;
  border-radius: 50%;
  border: 2px solid var(--color-border);
}

.hero h1 {
  margin: 0 0 0.5rem 0;
}

.hero p {
  margin: 0 0 1rem 0;
  color: var(--color-muted);
}

.button {
  display: inline-block;
  background: var(--color-accent);
  color: white;
  padding: 0.55rem 1.3rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
}
.button:hover,
.button:focus {
  background: var(--color-accent-hover);
  color: white;
}

/* Home feature cards */
.home-features {
  border-top: 1px solid var(--color-border);
  padding-top: 2rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  padding: 1.25rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
}

.feature-card h2 {
  margin: 0 0 0.5rem 0;
  font-size: 1.1rem;
}

.feature-card p {
  margin: 0 0 0.75rem 0;
  font-size: 0.95rem;
  color: var(--color-muted);
}

/* Project list */
.project-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.project-card {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1.5rem;
}

.project-card h3 {
  margin: 0 0 0.5rem 0;
}

.project-card p {
  margin: 0;
  color: var(--color-muted);
  font-size: 0.95rem;
}

.tag {
  display: inline-block;
  font-size: 0.75rem;
  background: #f3f4f6;
  color: var(--color-muted);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  margin-bottom: 0.5rem;
}

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

.article-header h1 {
  margin: 0 0 0.25rem 0;
}

.article-date {
  color: var(--color-muted);
  font-size: 0.9rem;
}

.article-body {
  max-width: 65ch;
}

.article-body img {
  max-width: 100%;
  height: auto;
  border-radius: 6px;
  border: 1px solid var(--color-border);
  display: block;
  margin: 1.5rem 0;
}

.back-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
  color: var(--color-muted);
  text-decoration: none;
}
.back-link:hover,
.back-link:focus {
  color: var(--color-accent);
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 600px) {
  .hero {
    flex-direction: column;
    text-align: center;
  }

  nav {
    flex-direction: column;
    gap: 0.75rem;
  }

  nav ul {
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
  }
}

:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
}