:root {
    --glass: rgba(255, 255, 255, 0.1);
    --glass-border: rgba(255, 255, 255, 0.2);
}

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

body {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: #0f172a;
    overflow: hidden;
}

/* Decoración de fondo */
.bg-decoration .circle {
    position: absolute;
    filter: blur(80px);
    z-index: -1;
    border-radius: 50%;
}
.circle:nth-child(1) { width: 300px; height: 300px; background: #3b82f6; top: 10%; left: 10%; }
.circle:nth-child(2) { width: 250px; height: 250px; background: #db2777; bottom: 10%; right: 10%; }

.calculator {
    background: var(--glass);
    backdrop-filter: blur(15px);
    -webkit-backdrop-filter: blur(15px);
    border: 1px solid var(--glass-border);
    padding: 20px;
    border-radius: 25px;
    width: 320px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.3);
}

.display {
    background: rgba(0, 0, 0, 0.3);
    padding: 20px;
    border-radius: 15px;
    text-align: right;
    margin-bottom: 20px;
    min-height: 90px;
}

.prev-val { color: rgba(255,255,255,0.5); font-size: 0.9rem; margin-bottom: 5px; }
.curr-val { color: white; font-size: 2rem; font-weight: 500; }

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

.btn {
    border: none;
    background: var(--glass);
    color: white;
    padding: 15px;
    font-size: 1.2rem;
    border-radius: 12px;
    cursor: pointer;
    transition: 0.3s;
}

.btn:hover { background: rgba(255,255,255,0.2); }
.btn-op { color: #60a5fa; font-weight: bold; }
.btn-special { color: #f87171; }
.btn-equal { background: #3b82f6; grid-row: span 2; }
.btn-zero { grid-column: span 2; }

@media (max-width: 400px) { .calculator { width: 90%; } }