body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #eef1f5;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}
.container {
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 450px;
    text-align: left;
}
.text-center {
    text-align: center;
}
h1 {
    color: #1a1a2e;
    margin-bottom: 20px;
}
h2 {
    color: #3e5c76;
    border-bottom: 1px solid #f0f0f0;
    padding-bottom: 10px;
    margin-top: 15px;
    margin-bottom: 20px;
}
.card {
    border: 1px solid #e0e0e0;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 25px;
}
input {
    width: 100%;
    padding: 12px;
    margin-bottom: 15px;
    border: 1px solid #ced4da;
    border-radius: 6px;
    box-sizing: border-box;
    transition: border-color 0.3s;
}
input:focus {
    border-color: #007bff;
    outline: none;
}
button {
    width: 100%;
    padding: 12px;
    margin-top: 10px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: background-color 0.3s;
}
.btn-primary {
    background-color: #007bff;
    color: white;
}
.btn-primary:hover {
    background-color: #0056b3;
}
.btn-secondary {
    background-color: #6c757d;
    color: white;
}
.btn-secondary:hover {
    background-color: #5a6268;
}
.btn-danger {
    background-color: #dc3545;
    color: white;
    margin-top: 20px;
}
.btn-danger:hover {
    background-color: #c82333;
}
.error {
    color: #dc3545;
    background-color: #f8d7da;
    border: 1px solid #f5c6cb;
    padding: 10px;
    border-radius: 6px;
    font-weight: 500;
    margin-bottom: 20px;
    display: none; /* Controlled by JS */
    text-align: center;
}
.success {
    color: #28a745;
    font-weight: bold;
}
.details {
    color: #6c757d;
}

/* New styles for the Tabbed Interface */
.container {
    /* Ensure text-align: left for general content */
    text-align: left;
}

/* Tab Navigation Styling */
.tab-nav {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 2px solid #eef1f5;
}

.tab-button {
    flex-grow: 1;
    padding: 15px 10px;
    border: none;
    background-color: transparent;
    color: #6c757d;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: color 0.3s, border-bottom 0.3s;
    border-radius: 0;
    margin: 0;
    border-bottom: 3px solid transparent;
    width: auto; /* Override 100% width from general button rule */
}

.tab-button:hover:not(.active) {
    color: #007bff;
}

.tab-button.active {
    color: #007bff;
    border-bottom: 3px solid #007bff;
}

/* Tab Content Visibility */
.tab-pane {
    display: none; /* Crucial: Hides all but the active tab */
    border: none; 
    padding: 0;
    margin-bottom: 0;
}

.tab-pane.active {
    display: block; /* Crucial: Shows the active tab */
}

/* Ensure the error message is centered under the title */
.error.text-center {
    text-align: center;
}