body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif, 'Microsoft YaHei', 'SimSun';
    background-color: #f4f4f4;
    color: #333;
    display: flex;
    justify-content: center;
    align-items: flex-start; /* Align to top for longer content */
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

.container {
    background-color: #fff;
    padding: 25px 40px;
    border-radius: 10px;
    box-shadow: 0 0 15px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 600px;
    text-align: center;
}

h1, h2 {
    color: #007bff; /* A nice blue */
}

#mode-selection button {
    padding: 10px 15px;
    font-size: 1em;
    margin: 0 10px 20px 10px;
    cursor: pointer;
    border: 1px solid #007bff;
    background-color: #fff;
    color: #007bff;
    border-radius: 5px;
    transition: background-color 0.3s, color 0.3s;
}

#mode-selection button.active-mode {
    background-color: #007bff;
    color: #fff;
}

.char-display {
    font-size: 4em; /* Large font for characters */
    font-weight: bold;
    margin: 20px 0;
    padding: 20px;
    background-color: #e9ecef;
    border-radius: 8px;
    min-height: 80px; /* Ensure height even if empty */
    display: flex;
    justify-content: center;
    align-items: center;
}

button {
    padding: 12px 20px;
    font-size: 1em;
    cursor: pointer;
    border-radius: 5px;
    border: none;
    margin: 5px;
    transition: background-color 0.2s ease;
}

#show-answer-btn {
    background-color: #28a745; /* Green */
    color: white;
}
#show-answer-btn:hover {
    background-color: #218838;
}

.feedback-btn {
    padding: 10px 15px;
}

.feedback-btn.correct {
    background-color: #5cb85c; /* Lighter Green */
    color: white;
}
.feedback-btn.correct:hover {
    background-color: #4cae4c;
}

.feedback-btn.incorrect {
    background-color: #d9534f; /* Red */
    color: white;
}
.feedback-btn.incorrect:hover {
    background-color: #c9302c;
}

#review-controls button {
    background-color: #17a2b8; /* Teal */
    color: white;
}
#review-controls button:hover {
    background-color: #138496;
}
#mark-as-learned-btn {
    background-color: #ffc107; /* Yellow */
    color: #333;
}
#mark-as-learned-btn:hover {
    background-color: #e0a800;
}

#stats {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #ddd;
    font-size: 0.9em;
    color: #555;
}
#stats p {
    margin: 5px 0;
}

/* Hide elements initially */
#traditional-char-display,
#feedback-buttons,
#review-section,
#manage-section,
#settings-section {
    display: none;
}

/* Add this to your style.css */
.warning-btn {
    background-color: #f0ad4e; /* Orange/Yellow for warning */
    color: white;
}
.warning-btn:hover {
    background-color: #ec971f;
}

/* Vocabulary Management Styles */
#search-container {
    margin: 20px 0;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 8px;
    border: 1px solid #dee2e6;
}

#search-input {
    flex: 1;
    max-width: 300px;
    padding: 10px 15px;
    border: 1px solid #ced4da;
    border-radius: 5px;
    font-size: 1em;
    background-color: white;
    transition: border-color 0.2s, box-shadow 0.2s;
}

#search-input:focus {
    outline: none;
    border-color: #007bff;
    box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}

#search-input::placeholder {
    color: #6c757d;
    font-style: italic;
}

#clear-search-btn {
    padding: 10px 15px;
    background-color: #6c757d;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.9em;
    transition: background-color 0.2s;
}

#clear-search-btn:hover {
    background-color: #5a6268;
}

#word-filter {
    margin: 20px 0;
    text-align: center;
}

.filter-btn {
    background-color: #6c757d;
    color: white;
    margin: 0 5px;
    padding: 8px 16px;
    font-size: 0.9em;
}

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

.filter-btn.active {
    background-color: #007bff;
}

#word-list-container {
    max-height: 400px;
    overflow-y: auto;
    border: 1px solid #ddd;
    border-radius: 5px;
    padding: 10px;
    margin: 20px 0;
}

.word-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px;
    margin: 5px 0;
    border-radius: 5px;
    background-color: #f8f9fa;
    border-left: 4px solid #dee2e6;
}

.word-item.state-not_learned {
    border-left-color: #dc3545; /* Red for not learned */
}

.word-item.state-learning {
    border-left-color: #ffc107; /* Yellow for learning */
}

.word-item.state-learned {
    border-left-color: #28a745; /* Green for learned */
}

.word-content {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.1em;
}

.simplified {
    font-weight: bold;
    color: #333;
}

.arrow {
    color: #6c757d;
}

.traditional {
    font-weight: bold;
    color: #007bff;
}

.word-controls {
    display: flex;
    gap: 5px;
}

.state-btn {
    padding: 4px 8px;
    font-size: 0.8em;
    border-radius: 3px;
    border: 1px solid #ddd;
    background-color: #fff;
    color: #333;
    cursor: pointer;
    transition: all 0.2s;
}

.state-btn:hover {
    background-color: #f8f9fa;
}

.state-btn.active {
    font-weight: bold;
}

.state-btn.not-learned.active {
    background-color: #dc3545;
    color: white;
    border-color: #dc3545;
}

.state-btn.learning.active {
    background-color: #ffc107;
    color: #333;
    border-color: #ffc107;
}

.state-btn.learned.active {
    background-color: #28a745;
    color: white;
    border-color: #28a745;
}

/* Start Learning and Settings Styles */
#start-learning-container {
    text-align: center;
    padding: 40px 20px;
}

.start-btn {
    background-color: #28a745;
    color: white;
    padding: 15px 30px;
    font-size: 1.2em;
    border-radius: 8px;
    margin: 20px 0;
}

.start-btn:hover {
    background-color: #218838;
}

#learning-status {
    margin-top: 15px;
    padding: 10px;
    background-color: #d4edda;
    border: 1px solid #c3e6cb;
    border-radius: 5px;
    color: #155724;
}

/* Settings Styles */
.setting-item {
    margin: 20px 0;
    padding: 15px;
    border: 1px solid #ddd;
    border-radius: 5px;
    background-color: #f8f9fa;
}

.setting-item label {
    display: block;
    font-weight: bold;
    margin-bottom: 8px;
    color: #333;
}

.setting-item input[type="number"],
.setting-item select {
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1em;
    margin-right: 10px;
    background-color: white;
}

.setting-item input[type="number"] {
    width: 80px;
}

.setting-item select {
    min-width: 300px;
}

.setting-description {
    display: block;
    font-size: 0.9em;
    color: #666;
    margin-top: 5px;
    font-style: italic;
}

.setting-actions {
    margin-top: 20px;
    text-align: center;
}

.save-btn {
    background-color: #007bff;
    color: white;
    padding: 10px 20px;
    margin: 0 10px;
}

.save-btn:hover {
    background-color: #0056b3;
}

/* Review Quality Buttons */
.quality-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: center;
    margin: 15px 0;
}

.quality-btn {
    padding: 8px 12px;
    font-size: 0.9em;
    border-radius: 5px;
    border: 1px solid #ddd;
    background-color: #f8f9fa;
    color: #333;
    cursor: pointer;
    transition: all 0.2s;
    min-width: 100px;
}

.quality-btn:hover {
    background-color: #e9ecef;
    border-color: #adb5bd;
}

.quality-btn[data-quality="0"],
.quality-btn[data-quality="1"] {
    border-color: #dc3545;
    color: #dc3545;
}

.quality-btn[data-quality="0"]:hover,
.quality-btn[data-quality="1"]:hover {
    background-color: #dc3545;
    color: white;
}

.quality-btn[data-quality="2"],
.quality-btn[data-quality="3"] {
    border-color: #ffc107;
    color: #856404;
}

.quality-btn[data-quality="2"]:hover,
.quality-btn[data-quality="3"]:hover {
    background-color: #ffc107;
    color: #212529;
}

.quality-btn[data-quality="4"],
.quality-btn[data-quality="5"] {
    border-color: #28a745;
    color: #28a745;
}

.quality-btn[data-quality="4"]:hover,
.quality-btn[data-quality="5"]:hover {
    background-color: #28a745;
    color: white;
}

/* Hotkey Styles */
.hotkey {
    font-size: 0.8em;
    background-color: rgba(0, 0, 0, 0.1);
    padding: 2px 6px;
    border-radius: 3px;
    margin-left: 8px;
    font-family: monospace;
    opacity: 0.7;
}

.hotkey-hints {
    margin-top: 10px;
    text-align: center;
    opacity: 0.8;
}

.hotkey-hints small {
    color: #666;
    font-style: italic;
}

.global-hotkey-hint {
    color: #666;
    font-style: italic;
    padding: 5px 10px;
    background-color: #f8f9fa;
    border-radius: 5px;
    display: inline-block;
}