/* CSS 2.1 / CSS 3 cơ bản, tương thích thiết bị cũ */
html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
    overflow: hidden;
    background-color: #f4f4f4;
    font-family: Arial, sans-serif;
    -webkit-user-select: none;
    user-select: none;
}

/* Thanh công cụ (Header) */
#toolbar {
    height: 50px;
    background-color: #333;
    color: #fff;
    display: table;
    width: 100%;
    box-sizing: border-box;
    padding: 0 10px;
}

.toolbar-content {
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}

button, .btn-upload {
    background-color: #555;
    color: white;
    border: 1px solid #777;
    padding: 8px 15px;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
    margin: 0 5px;
    display: inline-block;
    text-decoration: none;
}

.auth-user {
    color: #fff;
    font-size: 13px;
    margin-left: 8px;
}

button:active, .btn-upload:active {
    background-color: #777;
}

input[type="file"] {
    display: none;
}

/* Chân trang hiển thị số trang */
#footer {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 30px;
    background-color: #e0e0e0;
    color: #333;
    text-align: center;
    line-height: 30px;
    font-size: 14px;
    border-top: 1px solid #ccc;
}

/* Màn hình chờ tải */
#loading {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.7);
    color: white;
    z-index: 9999;
    display: none;
    text-align: center;
    padding-top: 40%;
    font-size: 18px;
}