body {
    margin: 0;
    padding: 0;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    background-color: #f0f2f5;
    color: #1c1e21;
}

.header {
    background-color: #4267b2;
    color: white;
    padding: 10px 0;
    text-align: center;
    text-shadow: 1px 1px 2px #000;  /* Thêm viền cho tiêu đề */
    position: relative;
}

.header h1 {
    margin: 0;
    font-size: 2.5em;
}

.header .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    position: relative;
}

.container {
    max-width: 800px;
    margin: 20px auto;
    padding: 20px;
    background-color: white;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
}

label, select, textarea, button {
    display: block;
    width: 100%;
    margin: 10px 0;
    padding: 10px;
    font-size: 1em;
    border: 1px solid #ddd;
    border-radius: 4px;
}

button {
    cursor: pointer;
    background-color: #4267b2;
    color: white;
    border: none;
}

button:hover {
    background-color: #365899;
}

.buttons {
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
}

table, th, td {
    border: 1px solid #ddd;
}

th, td {
    padding: 10px;
    text-align: left;
}

th {
    background-color: #f7f7f7;
}

.footer {
    text-align: center;
    margin-top: 10px;
    text-shadow: 1px 1px 2px #000;  /* Thêm viền cho dòng "Code By Nguyễn Vũ Tuấn" */
}

.footer a {
    color: red;
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

.tool-link {
    background-color: #e0e0e0;
    padding: 15px;
    border-radius: 8px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    font-size: 1.3em;
    position: absolute;
    top: 30%;
    right: 20px;
    transform: translateY(-50%);
}

.tool-link a {
    color: red;
    text-decoration: none;
    font-weight: bold;
}

.tool-link a:hover {
    text-decoration: underline;
}

@media screen and (max-width: 768px) {
    .tool-link {
        position: static;
        transform: none;
        margin-top: 20px;
        font-size: 1.1em;
    }
}