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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    max-width: 600px;
    width: 100%;
    padding: 40px;
}

h1 {
    color: #333;
    margin-bottom: 30px;
    text-align: center;
}

.footer-links {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #e9ecef;
    display: flex;
    flex-direction: column;
    gap: 10px;
    align-items: center;
}

.github-link {
    text-align: center;
}

.github-link a {
    color: #667eea;
    text-decoration: none;
    font-size: 14px;
    display: inline-flex;
    align-items: center;
    gap: 5px;
    transition: color 0.3s;
}

.github-link a:hover {
    color: #5568d3;
    text-decoration: underline;
}

.upload-section {
    margin-bottom: 30px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    text-align: center;
}

.upload-section.hidden {
    display: none;
}

.change-dictionary-link {
    text-align: center;
}

.change-dictionary-link a {
    color: #667eea;
    text-decoration: none;
    font-size: 14px;
    cursor: pointer;
    transition: color 0.3s;
}

.change-dictionary-link a:hover {
    color: #5568d3;
    text-decoration: underline;
}

.file-input-wrapper {
    position: relative;
    display: inline-block;
}

input[type="file"] {
    display: none;
}

.file-button {
    background: #667eea;
    color: white;
    padding: 12px 30px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    display: inline-block;
    transition: background 0.3s;
}

.file-button:hover {
    background: #5568d3;
}

.load-default-btn {
    background: #17a2b8;
    color: white;
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: background 0.3s;
}

.load-default-btn:hover {
    background: #138496;
}

.file-name {
    margin-top: 10px;
    color: #666;
    font-size: 14px;
}

.training-section {
    display: none;
}

.training-section.active {
    display: block;
}

.word-display {
    text-align: center;
    margin-bottom: 30px;
}

.concept {
    font-size: 48px;
    font-weight: bold;
    color: #333;
    margin-bottom: 20px;
}

.show-sign-btn {
    display: inline-block;
    background: #28a745;
    color: white;
    padding: 10px 20px;
    border-radius: 8px;
    border: none;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s;
}

.show-sign-btn:hover {
    background: #218838;
}

.iframe-container {
    margin-top: 20px;
    display: none;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    position: fixed;
    top: 10px;
    left: 10px;
    right: 10px;
    bottom: 10px;
    background: white;
    z-index: 1000;
}

.iframe-container.visible {
    display: flex;
    flex-direction: column;
}

.iframe-header {
    padding: 15px;
    background: #667eea;
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.iframe-header h3 {
    margin: 0;
    font-size: 18px;
}

.close-iframe-btn {
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    padding: 8px 16px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: background 0.3s;
}

.close-iframe-btn:hover {
    background: rgba(255,255,255,0.3);
}

.iframe-container iframe {
    width: 100%;
    flex: 1;
    border: none;
}

.action-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
}

button {
    flex: 1;
    padding: 15px 30px;
    font-size: 18px;
    font-weight: 600;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s;
}

.correct-btn {
    background: #28a745;
    color: white;
}

.correct-btn:hover {
    background: #218838;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(40, 167, 69, 0.4);
}

.wrong-btn {
    background: #dc3545;
    color: white;
}

.wrong-btn:hover {
    background: #c82333;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(220, 53, 69, 0.4);
}

.stats {
    margin-top: 30px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    text-align: center;
}

.stats-row {
    display: flex;
    justify-content: space-around;
    margin-top: 10px;
}

.stat-item {
    text-align: center;
}

.stat-value {
    font-size: 24px;
    font-weight: bold;
    color: #667eea;
}

.stat-label {
    font-size: 12px;
    color: #666;
    text-transform: uppercase;
}

.download-btn {
    margin-top: 20px;
    width: 100%;
    background: #ffc107;
    color: #333;
}

.download-btn:hover {
    background: #e0a800;
}

.google-drive-section {
    margin-top: 20px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    text-align: center;
}

.google-btn {
    background: #4285f4;
    color: white;
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    transition: background 0.3s;
    margin: 0 auto;
}

.google-btn:hover {
    background: #357ae8;
}

.google-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
}

.google-status {
    margin-top: 10px;
    font-size: 14px;
    color: #666;
}

.google-status.success {
    color: #28a745;
}

.google-status.error {
    color: #dc3545;
}

.progress-section {
    margin-top: 20px;
}

.word-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 10px;
    min-height: 30px;
}

.word-badge {
    background: #e9ecef;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 14px;
    color: #333;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.word-badge.learned {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.word-badge.learning {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.word-badge.learning-progress {
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.progress-indicator {
    font-size: 10px;
    font-weight: bold;
}

.start-lesson-btn {
    margin-top: 20px;
    background: #667eea;
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 18px;
    font-weight: 600;
    transition: all 0.3s;
}

.start-lesson-btn:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.review-section {
    margin-top: 15px;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 8px;
}

.review-section p {
    font-size: 14px;
    margin: 5px 0;
}

.review-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin: 10px 0;
}

.review-controls input[type="range"] {
    width: 150px;
    cursor: pointer;
}

.review-controls span {
    font-weight: bold;
    color: #667eea;
    min-width: 70px;
    text-align: right;
    font-size: 14px;
}

.start-review-btn {
    background: #17a2b8;
    color: white;
    padding: 8px 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s;
}

.start-review-btn:hover {
    background: #138496;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(23, 162, 184, 0.4);
}