body {
    background: linear-gradient(135deg, #2b5876 0%, #4e4376 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.button-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2em;
    max-width: 30em;
}

.btn {
    position: relative;
    width: 7em;
    height: 7em;
    border-radius: 50%;
    outline: none;
    border: none;
    background: linear-gradient(145deg, #444245, #2c2c2c);
    box-shadow: 8px 8px 15px rgba(0, 0, 0, 0.5), -8px -8px 15px rgba(255, 255, 255, 0.1);
    color: #ffffff;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:hover {
    transform: scale(1.1);
    box-shadow: 12px 12px 20px rgba(0, 0, 0, 0.7), -12px -12px 20px rgba(255, 255, 255, 0.2);
}

.btn span {
    font-size: 2.5em;
    transition: color 0.3s ease;
}

.btn::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    border-radius: 50%;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, rgba(0, 0, 0, 0) 70%);
    width: 8em;
    height: 8em;
    z-index: -1;
    transition: background 0.3s ease;
}

.btn.button-clicked {
    background: linear-gradient(-185deg, #131313, #444245);
    box-shadow: inset -2px -2px 0px #5e5e5e, inset 2px 2px 0px #1c1c1c;
}

.btn.button-clicked span {
    color: cyan;
}

.btn:active {
    transform: scale(0.95);
}
