:root {
  /* Core Colors */
  --bg-dark: #0f1115;
  --bg-card: #1a1d24;
  --bg-card-hover: #22262e;
  
  --primary: #8b5cf6;
  --primary-hover: #7c3aed;
  --primary-glow: rgba(139, 92, 246, 0.4);
  
  --secondary: #ec4899;
  --secondary-glow: rgba(236, 72, 153, 0.4);

  --accent: #14b8a6;
  
  /* Text Colors */
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  
  /* Utilities */
  --glass-bg: rgba(26, 29, 36, 0.7);
  --glass-border: rgba(255, 255, 255, 0.08);
  --radius-lg: 16px;
  --radius-xl: 24px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-display: 'Outfit', var(--font-sans);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* Typography Base */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

a {
  color: inherit;
  text-decoration: none;
  transition: var(--transition);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Utility Classes */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.text-gradient {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  color: transparent;
}

.glass-panel {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.875rem 1.75rem;
  border-radius: var(--radius-xl);
  font-weight: 600;
  font-family: var(--font-sans);
  transition: var(--transition);
  cursor: pointer;
  border: none;
  font-size: 1rem;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  box-shadow: 0 4px 14px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px var(--primary-glow);
  opacity: 0.95;
}

.btn-outline {
  background: transparent;
  color: var(--text-main);
  border: 1px solid var(--glass-border);
}

.btn-outline:hover {
  background: var(--glass-border);
}

/* Animations Core */
.fade-up {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.delay-100 { transition-delay: 100ms; }
.delay-200 { transition-delay: 200ms; }
.delay-300 { transition-delay: 300ms; }

/* Typewriter Cursor */
.typewriter-cursor {
  display: inline-block;
  width: 2px;
  height: 1em;
  background-color: var(--primary);
  margin-left: 4px;
  vertical-align: text-bottom;
  animation: blink 0.8s step-end infinite;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 10px;
}
::-webkit-scrollbar-track {
  background: var(--bg-dark);
}
::-webkit-scrollbar-thumb {
  background: var(--bg-card);
  border-radius: 5px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--primary);
}

/* Nav */
nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 1rem 0;
  z-index: 100;
  transition: var(--transition);
}

nav.scrolled {
  background: rgba(15, 17, 21, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--glass-border);
}

.nav-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-link {
  color: var(--text-main);
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition);
}

.nav-link:hover {
  color: var(--primary);
}

.logo {
  font-family: 'Playfair Display', serif;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-icon {
  color: var(--primary);
}

/* Store Badges */
.store-badges {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  align-items: center;
}

.store-badge {
  display: flex;
  align-items: center;
  background-color: var(--bg-card);
  color: white;
  padding: 10px 24px 10px 18px;
  border-radius: 16px;
  text-decoration: none;
  border: 1px solid var(--glass-border);
  transition: var(--transition);
  height: 64px;
}

.store-badge:hover {
  transform: translateY(-2px);
  border-color: rgba(255, 255, 255, 0.3);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.store-badge svg {
  margin-right: 14px;
  width: 32px;
  height: 32px;
}

.store-badge-text {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
}

.store-badge-small {
  font-size: 11px;
  line-height: 1.2;
  opacity: 0.7;
  margin-bottom: 2px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.store-badge-big {
  font-size: 20px;
  font-weight: 600;
  line-height: 1.1;
  font-family: var(--font-sans);
  letter-spacing: -0.5px;
}

.store-badge.rustore .rustore-icon {
  color: #005FF9;
}
.store-badge.apple .apple-icon {
  color: white;
}

/* Modal */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}
.modal-content {
  transform: translateY(20px);
  transition: transform 0.3s ease;
}
.modal-overlay.active .modal-content {
  transform: translateY(0);
}

/* SPA Navigation */
.spa-nav {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--glass-border);
  padding-bottom: 1rem;
}
.spa-nav-item {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 1.1rem;
  cursor: pointer;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-lg);
  transition: var(--transition);
}
.spa-nav-item:hover {
  background: var(--glass-bg);
  color: var(--text-main);
}
.spa-nav-item.active {
  background: var(--primary-glow);
  color: var(--text-main);
  border: 1px solid var(--primary);
}

/* Book Details Modal & Statuses */
.book-card {
  transition: transform 0.2s, box-shadow 0.2s;
  cursor: pointer;
  position: relative;
}
.book-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.5);
}
.book-card-badge {
  position: absolute;
  top: 8px;
  right: 8px;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  border-radius: 50%;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255,255,255,0.1);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  z-index: 2;
}
.book-card-favorite {
  position: absolute;
  top: 8px;
  left: 8px;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  border-radius: 50%;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255,255,255,0.1);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  z-index: 2;
  color: #ef4444;
}
.book-action-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--glass-border);
  color: var(--text-main);
  cursor: pointer;
  transition: all 0.2s;
  font-size: 0.95rem;
  justify-content: center;
  flex: 1;
}
.book-action-btn:hover {
  background: rgba(255,255,255,0.1);
}
.book-action-btn.active-reading {
  background: rgba(20, 184, 166, 0.2);
  border-color: var(--accent);
  color: var(--accent);
}
.book-action-btn.active-recommend {
  background: rgba(16, 185, 129, 0.2);
  border-color: #10b981;
  color: #10b981;
}
.book-action-btn.active-not_recommend {
  background: rgba(239, 68, 68, 0.2);
  border-color: #ef4444;
  color: #ef4444;
}

.auth-modal-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 42px;
  padding: 0 1.5rem;
  border-radius: 10px;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  transition: transform 0.2s ease, filter 0.2s ease;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.auth-modal-btn:hover {
  transform: translateY(-2px);
  filter: brightness(0.95);
}