#ob-floating-btn {
    position: fixed;
    bottom: 20px;
    left: 20px; /* Góc trái dưới */
    padding: 12px 22px;

    background: #0157FF;
    color: #ffffff;

    border-radius: 12px; /* Mềm hơn nhưng vẫn vuông tinh tế */
    border: none;

    font-size: 15px;
    font-weight: 600;
    font-family: Inter, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;

    cursor: pointer;
    z-index: 99999;

    box-shadow: 0 8px 18px rgba(0, 0, 0, 0.2);

    transition: all .25s ease;
}

#ob-floating-btn:hover {
    background: #0046C0;
    transform: translateY(-2px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.28);
}