:root {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-card-hover: #273549;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --accent: #2dd4bf;
  --accent-hover: #5eead4;
  --border: #334155;
  --tag-bg: #132e2a;
  --tag-text: #2dd4bf;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
}

a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-hover); }

/* Nav */
nav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
}
.nav-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 2rem;
  display: flex; justify-content: space-between; align-items: center;
}
.nav-brand { font-size: 1.25rem; font-weight: 700; color: var(--text); }
.nav-links { display: flex; gap: 2rem; list-style: none; }
.nav-links a { color: var(--text-muted); font-weight: 500; font-size: 0.95rem; }
.nav-links a:hover, .nav-links a.active { color: var(--accent); }

/* Container */
.container { max-width: 1100px; margin: 0 auto; padding: 0 2rem; }

/* Hero */
.hero {
  padding: 3rem 0 2.5rem;
  text-align: center;
}
.hero h1 { font-size: 2.75rem; font-weight: 800; margin-bottom: 1rem; line-height: 1.2; }
.hero .subtitle { font-size: 1.2rem; color: var(--text-muted); max-width: 600px; margin: 0 auto 2rem; }
.hero-links { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }
.hero-links a {
  padding: 0.5rem 1.25rem; border-radius: 8px; font-weight: 500; font-size: 0.95rem;
}
.btn-primary { background: var(--accent); color: var(--bg); }
.btn-primary:hover { background: var(--accent-hover); color: var(--bg); }
.btn-outline { border: 1px solid var(--border); color: var(--text-muted); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }

/* Section */
.section { padding: 1rem 0; }
.section-title { font-size: 1.75rem; font-weight: 700; margin-bottom: 0.5rem; }
.section-subtitle { color: var(--text-muted); margin-bottom: 2.5rem; }

/* Book Cards */
.book-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 2rem; }
.book-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 12px;
  padding: 2rem; transition: all 0.3s;
}
.book-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.book-card h3 { font-size: 1.25rem; margin-bottom: 0.5rem; }
.book-card .price { color: var(--accent); font-weight: 700; font-size: 1.1rem; margin-bottom: 0.75rem; }
.book-card p { color: var(--text-muted); font-size: 0.95rem; margin-bottom: 1.25rem; }
.book-card .tags { display: flex; gap: 0.5rem; flex-wrap: wrap; margin-bottom: 1.25rem; }
.tag {
  background: var(--tag-bg); color: var(--tag-text); padding: 0.2rem 0.6rem;
  border-radius: 4px; font-size: 0.8rem; font-weight: 500;
}
.book-card .btn-primary { display: inline-block; }

/* Blog Cards */
.blog-grid { display: grid; gap: 1.5rem; }
.blog-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 12px;
  padding: 1.75rem; transition: all 0.3s; display: block; color: var(--text);
}
.blog-card:hover { border-color: var(--accent); background: var(--bg-card-hover); color: var(--text); }
.blog-card .meta { color: var(--text-muted); font-size: 0.85rem; margin-bottom: 0.5rem; }
.blog-card h3 { font-size: 1.15rem; margin-bottom: 0.5rem; }
.blog-card p { color: var(--text-muted); font-size: 0.95rem; }
.blog-card .read-more { color: var(--accent); font-size: 0.9rem; margin-top: 0.75rem; display: inline-block; }

/* About */
.about-content { display: grid; grid-template-columns: 1fr 2fr; gap: 3rem; align-items: start; }
.about-photo {
  width: 200px; height: 200px; border-radius: 50%; background: var(--bg-card);
  border: 3px solid var(--border); display: flex; align-items: center; justify-content: center;
  font-size: 4rem; color: var(--text-muted);
}
.about-text p { color: var(--text-muted); margin-bottom: 1rem; }

/* Blog Post Page */
.blog-post { max-width: 750px; margin: 0 auto; padding: 4rem 2rem; }
.blog-post h1 { font-size: 2rem; margin-bottom: 0.5rem; }
.blog-post .meta { color: var(--text-muted); margin-bottom: 2rem; }
.blog-post p { margin-bottom: 1.25rem; }
.blog-post h2 { margin-top: 2rem; margin-bottom: 1rem; font-size: 1.4rem; }
.blog-post code { background: var(--bg-card); padding: 0.15rem 0.4rem; border-radius: 4px; font-size: 0.9rem; }
.blog-post pre { background: var(--bg-card); padding: 1.25rem; border-radius: 8px; overflow-x: auto; margin-bottom: 1.5rem; }
.blog-post pre code { background: none; padding: 0; }
.blog-post ul, .blog-post ol { padding-left: 1.5rem; margin-bottom: 1.25rem; }
.blog-post li { margin-bottom: 0.4rem; }

/* Footer */
footer {
  border-top: 1px solid var(--border); padding: 2rem 0; margin-top: 4rem;
  text-align: center; color: var(--text-muted); font-size: 0.9rem;
}

/* About flex layout */
.about-flex {
  display: flex;
  gap: 2.5rem;
  align-items: flex-start;
}
.about-photo-img {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--border);
  flex-shrink: 0;
}
.about-bio {
  flex: 1;
  min-width: 280px;
}

/* Filter buttons */
.filter-btn { cursor: pointer; border: none; transition: all 0.2s; }
.filter-btn:hover { background: var(--accent); color: var(--bg); }
.filter-btn.active { background: var(--accent); color: var(--bg); }

/* Responsive */
@media (max-width: 900px) {
  .hero h1 { font-size: 2rem; }
  .about-content { grid-template-columns: 1fr; justify-items: center; text-align: center; }
  .nav-links { gap: 1rem; }
  .about-flex { flex-direction: column; align-items: center; text-align: center; }
  .about-photo-img { margin: 0 auto; }
  .book-grid { grid-template-columns: 1fr; }
}