:root {
    --primary-color: #007bff;
    --primary-hover-color: #0056b3;
    --secondary-color: #6c757d;
    --background-color: #f8f9fa;
    --card-background-color: #ffffff;
    --text-color: #333;
    --label-color: #555;
    --border-color: #dee2e6;
    --border-radius: 8px;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --strength-weak: #dc3545;
    --strength-medium: #ffc107;
    --strength-strong: #28a745;
    --strength-very-strong: #17a2b8;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
}

.app-container {
    width: 100%;
    max-width: 700px;
    margin: 20px auto;
}

.app-header {
    text-align: center;
    margin-bottom: 30px;
    padding: 20px;
    background-color: var(--card-background-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.app-header h1 {
    color: var(--primary-color);
    margin-bottom: 10px;
    font-size: 2rem;
}

.app-header h1 i {
    margin-right: 10px;
}

.app-header p {
    color: var(--label-color);
    font-size: 0.95rem;
}

.card {
    background-color: var(--card-background-color);
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-bottom: 25px;
}

.card h2 {
    font-size: 1.4rem;
    color: var(--primary-color);
    margin-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 10px;
}

.card h2 i {
    margin-right: 8px;
    color: var(--secondary-color);
}

.password-display-container {
    display: flex;
    align-items: center;
    position: relative;
    margin-bottom: 10px;
}

#password-output {
    width: 100%;
    padding: 15px 50px 15px 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1.2rem;
    font-family: 'Courier New', Courier, monospace;
    background-color: #e9ecef;
    color: var(--text-color);
}

#copy-btn {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--secondary-color);
    transition: color 0.2s ease;
}

#copy-btn:hover {
    color: var(--primary-color);
}

.password-strength-indicator {
    position: absolute;
    bottom: -2px;
    left: 0;
    height: 4px;
    width: 0%;
    background-color: transparent;
    border-bottom-left-radius: var(--border-radius);
    border-bottom-right-radius: var(--border-radius);
    transition: width 0.3s ease, background-color 0.3s ease;
}

.password-strength-text {
    text-align: right;
    font-weight: bold;
    font-size: 0.9rem;
    height: 1.2em;
}

.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--label-color);
    font-size: 0.9rem;
}

input[type="number"], select {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

input[type="number"]:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
}

.slider-control {
    text-align: center;
}

input[type="range"] {
    width: 100%;
    margin-top: 10px;
    margin-bottom: 10px;
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
    height: 10px;
    background: #ddd;
    border-radius: 5px;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 22px;
    height: 22px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid var(--card-background-color);
    transition: background-color 0.2s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--primary-hover-color);
}

.slider-value-display {
    font-size: 1.1rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-top: 5px;
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.option {
    display: flex;
    align-items: center;
}

.option input[type="checkbox"] {
    width: 1.2em;
    height: 1.2em;
    margin-right: 10px;
}

.advanced-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

.btn-primary, .btn-secondary {
    display: block;
    width: 100%;
    padding: 15px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.1s ease;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover-color);
}

.btn-primary:active {
    transform: scale(0.98);
}

#multi-password-output {
    width: 100%;
    height: 150px;
    padding: 10px;
    font-family: 'Courier New', Courier, monospace;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 15px;
    resize: vertical;
}

.export-buttons {
    display: flex;
    gap: 10px;
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: white;
    font-size: 0.9rem;
    padding: 10px 15px;
}

.btn-secondary:hover {
    background-color: #5a6268;
}

#qrcode-container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 10px;
    background-color: #f8f9fa;
    border-radius: var(--border-radius);
}

.tips-list {
    list-style-type: none;
    padding-left: 0;
}

.tips-list li {
    margin-bottom: 10px;
    display: flex;
    align-items: center;
}

.tips-list i {
    margin-right: 12px;
    font-size: 1.2rem;
}

.fa-check-circle { color: var(--strength-strong); }
.fa-times-circle { color: var(--strength-weak); }