* {
    box-sizing: border-box;
}
body {
    margin: 0;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: url('https://source.unsplash.com/1600x900/?glass,technology') no-repeat center/cover;
    background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
    color: white;
    font-family: sans-serif;
}
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.calculator {
    background-color: rgba(255, 255, 255, 0.1); /* fallback */    
    background: rgba(255, 255, 255, 0.15);
    border-radius: 20px;
    padding: 20px;
    width: 320px;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
}
.display {
    width: 100%;
    height: 50px;
    font-size: 24px;
    border: none;
    border-radius: 10px;
    padding: 10px;
    margin-bottom: 10px;
    background: rgba(255,255,255,0.25);
    color: #fff;
    text-align: right;
}
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}
button {
    padding: 20px;
    font-size: 18px;
    background: rgba(255,255,255,0.2);
    border: none;
    border-radius: 10px;
    color: #fff;
    cursor: pointer;
    -webkit-backdrop-filter: blur(5px);
    backdrop-filter: blur(5px);
    transition: background 0.3s;
}

button.active {
  background-color: rgba(255, 255, 255, 0.2); /* light glow */
    transform: scale(1.05);
    box-shadow: 0 0 10px #ffffff80;
}

button {
    transition: all 0.1s ease;
}


button:hover {
    background: rgba(255,255,255,0.35);
}
button.zero {
    grid-column: span 2;
}

.calculator {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 20px;
    -webkit-backdrop-filter: blur(15px);
    backdrop-filter: blur(15px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.37);
    border: 1px solid rgba(255, 255, 255, 0.18);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.calculator:hover {
    transform: scale(1.01);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
}

button {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.25);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    border-radius: 12px;
    padding: 12px;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

button:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.3);
}

@keyframes popIn {
    0% {
    opacity: 0;
    transform: translateY(50px) scale(0.95);
}
    100% {
    opacity: 1;
    transform: translateY(0) scale(1);
}
}

.calculator {
    animation: popIn 0.5s ease-out;
}

/* Title (GlassCalc 🔮) */
.title {
    font-family: 'Orbitron', sans-serif;
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: 2px;
    margin-bottom: 10px;
    background: linear-gradient(90deg, #00ffe7, #fff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: pulseGlow 1s infinite alternate;
    text-align: center;
}

/* Tagline below title */
.tagline {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.7);
    font-style: italic;
    text-align: center;
    margin-bottom: 15px;
}

/* Text below display */
.helper-text {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.5);
    margin-top: 20px;
    margin-bottom: 0px;
    text-align: center;
}

/* Footer */
.footer-text {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.4);
    margin-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 10px;
    text-align: center;

}

/* Neon glow animation for title */
@keyframes pulseGlow {
  from {
    text-shadow: 0 0 8px #ccccccaf, 0 0 12px #00ffe7;
  }
  to {
    text-shadow: 0 0 15px #ccc, 0 0 35px #00ffe7;
  }
}