* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #091921;
    overflow: hidden;
}

/* Animated Background */
.bg-circles {
    position: absolute;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.circle {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    animation: move 10s infinite alternate;
}

.circle:nth-child(1) {
    width: 300px; height: 300px;
    background: #ff0057;
    top: -50px; left: -50px;
}

.circle:nth-child(2) {
    width: 250px; height: 250px;
    background: #00d2ff;
    bottom: -50px; right: -50px;
    animation-delay: -5s;
}

@keyframes move {
    from { transform: translate(0, 0); }
    to { transform: translate(100px, 100px); }
}

/* Glass Calculator */
.calculator {
    position: relative;
    width: 320px;
    padding: 20px;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.05);
    box-shadow: 0 25px 45px rgba(0,0,0,0.2);
    border: 1px solid rgba(255,255,255,0.1);
    backdrop-filter: blur(15px);
}

#display {
    width: 100%;
    background: transparent;
    border: none;
    outline: none;
    font-size: 2.5rem;
    color: #fff;
    text-align: right;
    margin-bottom: 20px;
    padding: 10px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

button {
    height: 60px;
    border-radius: 12px;
    border: 1px solid rgba(255,255,255,0.1);
    background: rgba(255, 255, 255, 0.05);
    color: #fff;
    font-size: 1.2rem;
    cursor: pointer;
    transition: 0.3s;
}

/* Hover & Click Animations */
button:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

button:active {
    transform: translateY(0px);
}

.operator { color: #00d2ff; font-weight: bold; }
.action { color: #ff0057; }
.equal { 
    background: #00d2ff; 
    color: #091921; 
    font-weight: bold;
}
.equal:hover { background: #fff; }
.span-two { grid-column: span 2; }