/* --- Thiết lập Responsive Container --- */
.hanzi-main-wrapper {
    width: 100%; 
    max-width: 400px; 
    margin: 20px auto; 
    padding: 10px;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.hanzi-writer-container {
    background-color: #f7f7f7;
    border: 1px solid #d4d4d4 !important;
    border-radius: 4px;
    overflow: hidden; 
}

/* --- Định dạng thanh điều khiển (Controls) --- */
.hanzi-controls {
    display: flex;
    justify-content: center; 
    padding: 15px 0 5px;
    gap: 15px; 
}

.hanzi-btn {
    background: #ffffff;
    color: #4CAF50; 
    border: 2px solid #ddd;
    border-radius: 50%; 
    width: 45px;
    height: 45px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    font-size: 18px; 
}

.hanzi-btn:hover {
    background-color: #f0f0f0;
    border-color: #c0c0c0;
}

.hanzi-btn.active {
    background-color: #4CAF50;
    color: white;
    border-color: #388e3c;
}

/* --- Tối ưu cho thiết bị di động --- */
@media (max-width: 600px) {
    .hanzi-main-wrapper {
        padding: 5px;
        margin: 10px auto;
    }
    .hanzi-btn {
        width: 40px; 
        height: 40px;
        font-size: 16px;
    }
}