body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: linear-gradient(to bottom, #BBDEFB, #C8E6C9);
    min-height: 100vh;
}
.container, .login-container {
    max-width: 600px;
    margin: auto;
    padding: 20px;
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 90%;
    max-width: 600px; /* FitFun-Design */
}
h1, h2 {
    text-align: center;
    color: #333;
    font-size: 22px;
    margin: 10px 0;
}
p {
    text-align: center;
    color: #555;
    margin-bottom: 15px;
}
.date-picker {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    margin: 10px 0;
}
.date-picker form {
    width: 100%;
    text-align: center;
}
.date-picker input[type="date"] {
    padding: 8px;
    font-size: 16px;
    border: 1px solid #ccc;
    border-radius: 4px;
    width: 160px;
    text-align: center;
}
.button-group {
    display: flex;
    gap: 10px;
    justify-content: center;
}
.members-button, .export-button, .logout-button {
    padding: 8px 16px;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    width: 160px;
    min-width: 160px;
    max-width: 160px;
    text-align: center;
    text-decoration: none;
    box-sizing: border-box;
    display: inline-block;
}
.members-button {
    background-color: #FF9800;
}
.members-button:hover {
    background-color: #F57C00;
}
.export-button {
    background-color: #4CAF50;
}
.logout-container {
    display: flex;
    justify-content: center;
    margin-bottom: 10px;
}
.back-button-container {
    display: flex;
    justify-content: center;
    margin-bottom: 10px;
}
.logout-button {
    background-color: #2196F3;
}
.export-button:hover {
    background-color: #45a049;
}
.logout-button:hover {
    background-color: #1976D2;
}
table {
    width: 100%;
    border-collapse: collapse;
    background-color: #fff;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
th, td {
    padding: 10px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}
th {
    background-color: #4CAF50;
    color: white;
    font-weight: bold;
}
tr:nth-child(even) {
    background-color: #f9f9f9;
}
tr:hover {
    background-color: #f1f1f1;
}
input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}
.login-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    max-width: 600px;
    margin: 20px auto;
}
.login-container form {
    width: 100%;
}
.login-container label {
    font-size: 14px;
    color: #555;
    margin-bottom: 5px;
    display: block;
}
.login-container input[type="text"], .login-container input[type="password"] {
    width: 100%;
    padding: 10px;
    margin: 8px 0;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
    box-sizing: border-box;
}
.login-container button {
    width: 100%;
    padding: 10px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 16px;
    cursor: pointer;
}
.login-container button:hover {
    background-color: #45a049;
}
.error-message {
    color: red;
    text-align: center;
    margin-top: 10px;
    font-size: 14px;
}
.success-message {
    color: green;
    text-align: center;
    margin-top: 10px;
    font-size: 14px;
}
.add-participant {
    margin: 20px 0;
    text-align: center;
}
.add-participant input[type="text"] {
    padding: 8px;
    font-size: 16px;
    border: 1px solid #ccc;
    border-radius: 4px;
    width: 200px;
    margin-right: 10px;
}
.add-button, .delete-button {
    padding: 8px 16px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
}
.delete-button {
    background-color: #f44336;
}
.add-button:hover {
    background-color: #45a049;
}
.delete-button:hover {
    background-color: #d32f2f;
}
.back-button {
    display: inline-block;
    padding: 8px 16px;
    background-color: #2196F3;
    color: white;
    border-radius: 4px;
    text-decoration: none;
    font-size: 16px;
    text-align: center;
    width: 160px;
    min-width: 160px;
    max-width: 160px;
    box-sizing: border-box;
}
.back-button:hover {
    background-color: #1976D2;
}
footer {
    text-align: center;
    padding: 10px 0;
    color: #555;
    font-size: 14px;
}
@media (max-width: 400px) {
    .container, .login-container {
        padding: 8px;
        max-width: 90%;
    }
    h1, h2 {
        font-size: 18px;
        margin: 8px 0;
    }
    .date-picker {
        gap: 6px;
        margin: 8px 0;
    }
    .date-picker input[type="date"] {
        font-size: 14px;
        width: 140px;
    }
    .button-group {
        flex-direction: column;
        gap: 6px;
    }
    .members-button, .export-button, .logout-button, .back-button {
        font-size: 14px;
        padding: 6px 12px;
        width: 140px;
        min-width: 140px;
        max-width: 140px;
    }
    th, td {
        padding: 6px;
        font-size: 12px;
    }
    input[type="checkbox"] {
        width: 16px;
        height: 16px;
    }
    .login-container input[type="text"], .login-container input[type="password"], .login-container button {
        font-size: 14px;
        padding: 8px;
    }
    .add-participant input[type="text"] {
        width: 100%;
        margin-bottom: 10px;
        margin-right: 0;
    }
    .add-button, .delete-button {
        font-size: 14px;
        padding: 6px 12px;
        width: 100%;
    }
}