:root {
  --bg-color: #0b0f19;
  --card-bg: rgba(18, 24, 38, 0.75);
  --text-main: #f3f4f6;
  --text-sub: #9ca3af;
  --primary-glow: rgba(59, 130, 246, 0.5);
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --wa-color: #25d366;
  --wa-glow: rgba(37, 211, 102, 0.5);
  --border-color: rgba(255, 255, 255, 0.1);
}

[data-theme="light"] {
  --bg-color: #f0f4f8;
  --card-bg: rgba(255, 255, 255, 0.85);
  --text-main: #1f2937;
  --text-sub: #4b5563;
  --primary-glow: rgba(59, 130, 246, 0.25);
  --accent-color: #2563eb;
  --accent-hover: #1d4ed8;
  --border-color: rgba(0, 0, 0, 0.08);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  transition: background-color 0.3s ease, color 0.3s ease;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Loading Overlay */
.loader-overlay {
  position: fixed;
  inset: 0;
  background: var(--bg-color);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity 0.4s ease, visibility 0.4s ease;
}
.loader-overlay.fade-out {
  opacity: 0;
  visibility: hidden;
}
.spinner {
  width: 50px;
  height: 50px;
  border: 4px solid var(--border-color);
  border-top-color: var(--accent-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: 12px;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* Navbar */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 40px;
  backdrop-filter: blur(10px);
}
.logo {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: 1px;
}
.logo span { color: var(--accent-color); }
.nav-controls {
  display: flex;
  gap: 12px;
  align-items: center;
}

/* Glowing Buttons Effect */
.glow-btn {
  border: 1px solid var(--border-color);
  padding: 10px 18px;
  border-radius: 12px;
  cursor: pointer;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  position: relative;
  overflow: hidden;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  text-decoration: none;
}
.glow-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 20px var(--primary-glow);
}
.glow-btn:active {
  transform: translateY(0);
}

.wa-mini-btn {
  background: var(--wa-color);
  color: #fff;
  width: 42px;
  height: 42px;
  padding: 0;
  font-size: 1.2rem;
  border-radius: 10px;
}
.wa-mini-btn:hover {
  box-shadow: 0 0 20px var(--wa-glow);
}

.theme-btn {
  background: var(--card-bg);
  color: var(--text-main);
  width: 42px;
  height: 42px;
  padding: 0;
  border-radius: 10px;
}

/* Container & Glass Card */
.container {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.glass-card {
  background: var(--card-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  padding: 35px;
  width: 100%;
  max-width: 500px;
  box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}

.header h1 { font-size: 1.8rem; margin-bottom: 8px; }
.header p { color: var(--text-sub); font-size: 0.95rem; margin-bottom: 25px; }

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 25px;
}
.stat-item {
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border-color);
  border-radius: 14px;
  padding: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.stat-item i { font-size: 1.2rem; color: var(--accent-color); }
.stat-label { font-size: 0.7rem; color: var(--text-sub); display: block; }
.stat-value { font-size: 0.85rem; font-weight: 700; color: var(--text-main); }

/* Form */
.pairing-form .input-group {
  margin-bottom: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.input-group label { font-size: 0.85rem; color: var(--text-sub); }
.input-group input {
  padding: 14px 16px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  background: rgba(0,0,0,0.1);
  color: var(--text-main);
  outline: none;
  font-size: 1rem;
}
.input-group input:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 10px var(--primary-glow);
}

.btn-submit {
  width: 100%;
  padding: 14px;
  background: var(--accent-color);
  color: #fff;
  font-size: 1rem;
}

/* Result Box */
.code-result-box {
  margin-top: 25px;
  padding: 20px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px dashed var(--accent-color);
  border-radius: 16px;
  text-align: center;
}
.code-display {
  font-size: 1.8rem;
  font-weight: 900;
  letter-spacing: 4px;
  color: var(--accent-color);
  margin: 12px 0;
  user-select: all;
}
.code-hint { font-size: 0.75rem; color: var(--text-sub); }
.hidden { display: none; }

/* Modal */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.7);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}
.modal-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 30px;
  max-width: 400px;
  text-align: center;
}
.modal-icon i { font-size: 3rem; color: var(--wa-color); margin-bottom: 15px; }
.modal-card h2 { margin-bottom: 10px; }
.modal-card p { font-size: 0.9rem; color: var(--text-sub); margin-bottom: 20px; }
.modal-actions { display: flex; gap: 10px; justify-content: center; }
.btn-primary { background: var(--wa-color); color: #fff; }
.btn-secondary { background: transparent; color: var(--text-sub); }