:root {
  --bg: #f8fafc;
  --card-bg: rgba(255, 255, 255, 0.7);
  --text: #1e293b;
  --accent: #6366f1;
  --secondary: #10b981;
  --glass-border: rgba(255, 255, 255, 0.4);
}

body.dark {
  --bg: #0f172a;
  --card-bg: rgba(30, 41, 59, 0.7);
  --text: #f1f5f9;
  --glass-border: rgba(255, 255, 255, 0.1);
}

* {
  box-sizing: border-box;
  transition: background 0.4s ease, color 0.4s ease;
}

body {
  margin: 0;
  font-family: 'Inter', sans-serif;
  background-color: var(--bg);
  color: var(--text);
  overflow-x: hidden;
  min-height: 100vh;
}

/* Background Animated Blobs */
.background-blobs {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  z-index: -1;
  background: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.1) 0%, transparent 40%),
              radial-gradient(circle at 90% 80%, rgba(16, 185, 129, 0.1) 0%, transparent 40%);
}

header {
  padding: 60px 20px 40px;
  text-align: center;
}

header h1 {
  font-size: 2.5rem;
  letter-spacing: -1px;
  margin-bottom: 10px;
}

#counter {
  font-size: 0.9rem;
  opacity: 0.7;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 15px;
  margin-top: 30px;
}

.search-wrapper {
  position: relative;
}

#search {
  padding: 14px 25px;
  width: 320px;
  border-radius: 50px;
  border: 1px solid var(--glass-border);
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  color: var(--text);
  font-size: 1rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
  outline: none;
}

#search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.2);
}

#toggleMode {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  border: none;
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  cursor: pointer;
  font-size: 1.2rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}

/* Library Grid */
.library {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 30px;
}

/* Book Card */
.book {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  padding: 30px;
  text-align: center;
  position: relative;
  animation: fadeIn 0.6s ease backwards;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.book:hover {
  transform: translateY(-10px) scale(1.02);
  box-shadow: 0 20px 40px rgba(0,0,0,0.1);
  border-color: var(--accent);
}

.book-icon {
  font-size: 3rem;
  margin-bottom: 15px;
  filter: drop-shadow(0 5px 10px rgba(0,0,0,0.1));
}

.book h3 {
  margin: 0 0 20px;
  font-weight: 600;
  font-size: 1.25rem;
}

.actions {
  display: flex;
  gap: 10px;
}

.actions a {
  flex: 1;
  padding: 12px;
  border-radius: 12px;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  color: white;
  background: var(--accent);
  transition: filter 0.2s;
}

.actions a.dl {
  background: var(--secondary);
}

.actions a:hover {
  filter: brightness(1.1);
}

/* Responsive tweaks */
@media (max-width: 420px) {
  #search { width: 220px; padding: 12px 18px; }
  header { padding-top: 40px; }
  .book { padding: 20px; }
}