/* Glassmorphism + Responsive + Modern Animation */

:root {
    --blur-bg: rgba(255, 255, 255, 0.1);
    --border-glow: rgba(255, 255, 255, 0.3);
    --text-glow: rgba(255, 255, 255, 0.8);
    --accent: #00f2fe;
    --accent2: #4facfe;
  }
  
  * {
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  }
  
  body {
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, #1e1e2f, #3a3a5c);
    overflow: hidden;
  }
  
  .glass-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    backdrop-filter: blur(10px);
    animation: fadeIn 1s ease-in-out;
  }
  
  @keyframes fadeIn {
    from { opacity: 0; transform: scale(0.95); }
    to   { opacity: 1; transform: scale(1); }
  }
  
  .calculator {
    background: var(--blur-bg);
    border: 1px solid var(--border-glow);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.37);
    border-radius: 20px;
    padding: 20px;
    width: 320px;
    max-width: 90%;
    backdrop-filter: blur(25px);
    transition: all 0.3s ease;
  }
  
  #display {
    width: 100%;
    padding: 15px;
    margin-bottom: 20px;
    font-size: 1.7rem;
    border: none;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.05);
    color: white;
    text-align: right;
    backdrop-filter: blur(8px);
    box-shadow: inset 0 0 10px rgba(255, 255, 255, 0.1);
    animation: inputGlow 4s infinite alternate;
  }
  
  @keyframes inputGlow {
    0% { box-shadow: inset 0 0 10px var(--accent); }
    100% { box-shadow: inset 0 0 20px var(--accent2); }
  }
  
  #keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
  }
  
  #keys button {
    padding: 15px;
    font-size: 1.3rem;
    border: none;
    border-radius: 12px;
    background: linear-gradient(145deg, #2d2d4a, #1e1e33);
    color: #ffffffcc;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
    transition: transform 0.15s ease, background 0.3s ease;
  }
  
  #keys button:hover {
    transform: scale(1.08);
    background: linear-gradient(145deg, #00f2fe, #4facfe);
    color: white;
  }
  
  #keys button:active {
    transform: scale(0.95);
    background: #14142b;
  }
  
  #keys button[value="="] {
    background: linear-gradient(to right, #00f2fe, #4facfe);
    color: white;
    font-weight: bold;
    animation: pulse 2s infinite;
  }
  
  @keyframes pulse {
    0% { box-shadow: 0 0 10px var(--accent); }
    100% { box-shadow: 0 0 20px var(--accent2); }
  }
  
  #keys button[value="AC"],
  #keys button[value="Del"] {
    background: linear-gradient(to right, #ff416c, #ff4b2b);
    color: white;
  }
  
  footer {
    margin-top: 20px;
    color: #ffffffa8;
    font-size: 0.9rem;
    animation: textPulse 3s infinite alternate;
  }
  
  @keyframes textPulse {
    0% { text-shadow: 0 0 5px var(--accent); }
    100% { text-shadow: 0 0 10px var(--accent2); }
  }