* {
    box-sizing: border-box;
    font-family: 'Segoe UI', sans-serif;
}

body {
    margin: 0;
    height: 100vh;
    background: radial-gradient(circle at top, #1a1a1a, #000);
    display: flex;
    align-items: center;
    justify-content: center;
}

.calculator {
    background: rgba(255, 255, 255, 0.06); /* more subtle transparency */
    border-radius: 20px;
    padding: 20px;
    width: 320px;
    box-shadow: 
        0 8px 25px rgba(0, 0, 0, 0.6); /* remove neon glow */
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.display {
    background: rgba(0, 0, 0, 0.85);
    color: #00e6d8;
    font-size: 2.2rem;
    padding: 15px;
    border-radius: 12px;
    text-align: right;
    margin-bottom: 15px;
    box-shadow: inset 0 0 5px rgba(0, 255, 255, 0.15);
}


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

button {
    padding: 15px;
    font-size: 1.1rem;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    background: #111;
    color: #fff;
    transition: all 0.2s ease;
}

button:hover {
    transform: translateY(-1px);
    box-shadow: 0 0 6px rgba(0, 255, 255, 0.25);
}

button:active {
    transform: scale(0.95);
}

.operator {
    background: #003333;
    color: #00ffe7;
}

.equal {
    background: linear-gradient(135deg, #00ffe7, #007777);
    color: #000;
    grid-column: span 2;
    font-weight: bold;
}

.clear {
    background: #330000;
    color: #ff4d4d;
}

.delete {
    background: #003333;
    color: #00ffe7;
}