body {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background: linear-gradient(135deg, #000000, #333333);
    color: #fff;
    overflow: hidden;
}

#background-video {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: -1;
}

h1 {
    margin-bottom: 20px;
    font-size: 2.5em;
    text-align: center;
    font-family: 'Courier New', monospace;
}

h1 span {
    display: inline-block;
    animation: glow 2s ease-in-out infinite alternate, type 3s steps(10, end) 1s both;
}

@keyframes type {
    from {
        width: 0;
    }
    to {
        width: 100%;
    }
}

@keyframes glow {
    from {
        text-shadow: 0 0 5px #fff, 0 0 10px #fff, 0 0 15px #fff, 0 0 20px #ff9500;
    }
    to {
        text-shadow: 0 0 10px #fff, 0 0 20px #fff, 0 0 30px #fff, 0 0 40px #ff9500;
    }
}

.calculator {
    background-color: #333;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.2);
    padding: 20px;
    width: 300px;
}

.display {
    margin-bottom: 20px;
}

#display {
    width: 100%;
    height: 60px;
    font-size: 24px;
    text-align: right;
    padding: 10px;
    border: none;
    border-radius: 5px;
    background-color: #fff;
    box-sizing: border-box;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.btn.operator:nth-child(2) {
    background-color: #a6a6a6;
    color: #000;
}

.btn.operator:nth-child(3) {
    background-color: #a6a6a6;
    color: #302d2d;
}

.btn {
    height: 60px;
    font-size: 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn:hover {
    opacity: 0.8;
}

.number {
    background-color: #666;
    color: #fff;
}

.operator {
    background-color: #696269;
    color: #fff;
}

.clear {
    background-color: #a6a6a6;
    color: #000;
}

.equal {
    background-color: #ff9500;
    color: #fff;
    grid-column: span 2;
}

.zero {
    grid-column: span 2;
}

.backspace {
    background-color: #a6a6a6;
    color: #000;
}

p {
    margin-top: 20px;
    font-size: 1.2em;
    text-align: center;
    color: #12d396;
    font-family: 'Courier New', monospace;
    font-weight: bold;
    text-shadow: 0 0 10px #12d396, 0 0 20px #12d396, 0 0 30px #12d396;
}

p span {
    display: inline-block;
    animation: fadeIn 3s ease-in-out, typeP 4s steps(40, end) 1s both;
}

@keyframes typeP {
    from {
        width: 0;
    }
    to {
        width: 100%;
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}