body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #f4f7f6;
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
}
.container {
    background-color: #ffffff;
    padding: 20px 30px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    width: 100%;
    max-width: 600px;
    box-sizing: border-box;
}
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid #eee;
    padding-bottom: 10px;
}
h1 {
    color: #333;
    margin-top: 0;
}
h2 {
    color: #555;
    border-bottom: 1px solid #eee;
    padding-bottom: 5px;
}
input[type="email"],
input[type="password"] {
    width: calc(100% - 22px); /* 100% - padding*2 - border*2 */
    padding: 10px;
    margin: 10px 0;
    border: 1px solid #ddd;
    border-radius: 4px;
}
input[type="file"] {
    width: 100%;
    margin: 10px 0;
}
button {
    background-color: #007bff;
    color: white;
    padding: 12px 18px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    margin: 5px;
    transition: background-color 0.2s;
}
button:hover {
    background-color: #0056b3;
}
button:disabled {
    background-color: #cccccc;
    cursor: not-allowed;
}
#logout-btn {
    background-color: #dc3545;
    font-size: 14px;
    padding: 8px 12px;
}
#logout-btn:hover {
    background-color: #c82333;
}
#auth-message, #upload-message {
    margin-top: 15px;
    font-size: 14px;
    word-wrap: break-word;
}
.success {
    color: green;
}
.error {
    color: red;
}

/* Spinner animation */
.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 20px;
    height: 20px;
    animation: spin 1s linear infinite;
    display: inline-block;
    margin-left: 10px;
    vertical-align: middle;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }

}