* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: radial-gradient(circle at top left, #1e1e2f, #0f0c29);
}

.calculator {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: 25px;
    border-radius: 30px;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.6);
    width: 420px;
}

#screen {
    width: 100%;
    height: 80px;
    background: rgba(0, 0, 0, 0.3);
    border: none;
    outline: none;
    border-radius: 15px;
    color: #00ffcc;
    text-align: right;
    padding: 0 20px;
    font-size: 2.2rem;
    margin-bottom: 25px;
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.5);
}

.buttons {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 12px;
}

.btn {
    height: 60px;
    border-radius: 15px;
    border: none;
    background: rgba(255, 255, 255, 0.08);
    color: #fff;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
}

.btn:active {
    transform: translateY(0);
}

.sci {
    background: rgba(138, 43, 226, 0.15);
    color: #bb86fc;
    font-size: 0.95rem;
}

.operator {
    background: rgba(255, 159, 10, 0.15);
    color: #ff9f0a;
    font-weight: bold;
}

.special {
    background: rgba(255, 69, 58, 0.15);
    color: #ff453a;
}

.equal {
    grid-row: span 2;
    height: 100%;
    background: linear-gradient(135deg, #00d2ff, #3a7bd5);
    color: white;
    font-weight: bold;
    font-size: 1.5rem;
}

.zero {
    grid-column: span 2;
}