:root {
  --bg-color: #e0f2fe; /* Light blue background */
  --text-color: #0f172a;
  --glass-bg: rgba(255, 255, 255, 0.4);
  --glass-border: rgba(255, 255, 255, 0.2);
  --accent-blue: #3b82f6;
  --card-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.15);
  --transition: all 0.3s ease;
}

[data-theme="dark"] {
  --bg-color: #0f172a; /* Deep blue/black background */
  --text-color: #f1f5f9;
  --glass-bg: rgba(30, 41, 59, 0.4);
  --glass-border: rgba(255, 255, 255, 0.1);
  --accent-blue: #60a5fa;
  --card-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.3);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: var(--transition);
  min-height: 100vh;
  padding: 2rem;
  overflow-x: hidden;
}

.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: 15px;
  border: 1px solid var(--glass-border);
  box-shadow: var(--card-shadow);
}

.btn {
  background-color: var(--accent-blue);
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  transition: var(--transition);
}

.btn:hover {
  opacity: 0.9;
  transform: translateY(-2px);
}

.input {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  padding: 0.5rem;
  border-radius: 8px;
  color: var(--text-color);
  width: 100%;
  margin-bottom: 1rem;
}

.theme-toggle {
  position: fixed;
  top: 1rem;
  right: 1rem;
  z-index: 1000;
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 50%;
  background: var(--glass-bg);
  backdrop-filter: blur(5px);
  -webkit-backdrop-filter: blur(5px);
  border: 1px solid var(--glass-border);
  color: var(--accent-blue);
  font-size: 1.5rem;
  width: 45px;
  height: 45px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem;
}

.back-btn {
  position: fixed;
  top: 1rem;
  left: 1rem;
  text-decoration: none;
  color: var(--accent-blue);
  font-weight: bold;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}