body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    font-family: 'Kanit', Arial, sans-serif;
    font-size: 14px;
    line-height: 1.5;
    margin: 0;
}

#container {
    margin: 20px auto 0 auto;
    width: 95%;
    max-width: 450px;
    padding: 15px;
    border: 1px solid #ccc;
    background-color: #FFFFFF;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    box-sizing: border-box;
}

.logo {
    display: block;
    margin: 0 auto 15px auto;
    width: 80px;
    height: auto;
}

h3 {
    margin-top: 0;
    margin-bottom: 10px;
    font-weight: 700;
    font-size: 18px;
    text-align: center;
}

.intro-text {
    text-align: center;
    margin-bottom: 20px;
    display: block;
}

form {
    margin-top: 10px;
}

.input-group {
    display: flex;
    align-items: stretch;
    margin-top: 5px;
    margin-bottom: 15px;
}

label {
    font-weight: bold;
    display: block;
    margin-bottom: 5px;
}

#callsign {
    flex-grow: 1;
    padding: 10px;
    font-size: 14px;
    border: 1px solid #ccc;
    border-radius: 5px;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

button {
    padding: 10px 15px;
    border: none;
    cursor: pointer;
    background-color: #00874a;
    color: white;
    font-size: 14px;
    font-weight: 700;
    border-radius: 5px;
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #006a3a;
}

#passcode {
    font-size: 16px;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    background-color: #e9e9e9;
}

#passcode b {
    color: #00874a;
}

footer {
    width: 100%;
    padding: 15px 0;
    background-color: #e9ecef;
    color: #6c757d;
    font-size: 0.9em;
    text-align: center;
    margin-top: auto; /* ดัน footer ลงด้านล่าง */
}

footer a {
    color: #007bff;
    text-decoration: none;
    font-weight: 600;
}

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