body {
    margin: 0;
    padding: 0;
    color: rgba(255, 255, 255, 0.87);
    background-color: #0f0f0f;
}

#app {
    width: 100%;
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

#exit-btn {
    position: fixed;
    top: 12px;
    right: 16px;
    z-index: 1000;
    background: rgba(30, 30, 30, 0.85);
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.35);
    border-radius: 8px;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    text-decoration: none;
    cursor: pointer;
    transition: background 0.15s, border-color 0.15s;
}

#exit-btn:hover {
    background: rgba(200, 50, 50, 0.85);
    border-color: rgba(255, 100, 100, 0.7);
}