/* 自定义样式 */
:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #059669;
    --warning-color: #d97706;
    --error-color: #dc2626;
    --font-family: 'Inter', sans-serif;
}

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, #f0f9ff 0%, #e0e7ff 100%);
    min-height: 100vh;
}

/* 动画效果 */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.fade-in {
    animation: fadeIn 0.5s ease-out;
}

.pulse-animation {
    animation: pulse 1s ease-in-out;
}

.shake-animation {
    animation: shake 0.5s ease-in-out;
}

/* 卡片样式 */
.card {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    transition: all 0.3s ease;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

/* 按钮样式 */
.btn {
    padding: 12px 24px;
    border-radius: 8px;
    font-weight: 500;
    transition: all 0.2s ease;
    border: none;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

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

.btn-primary:hover {
    background-color: #1d4ed8;
    transform: translateY(-1px);
}

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

.btn-secondary:hover {
    background-color: #475569;
}

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

.btn-success:hover {
    background-color: #047857;
}

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

.btn-warning:hover {
    background-color: #b45309;
}

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

.btn-error:hover {
    background-color: #b91c1c;
}

/* 选项按钮样式 */
.option-btn {
    padding: 16px;
    border: 2px solid #e5e7eb;
    border-radius: 12px;
    background: white;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    font-weight: 500;
}

.option-btn:hover {
    border-color: var(--primary-color);
    background-color: #f0f9ff;
    transform: translateY(-2px);
}

.option-btn.selected {
    border-color: var(--primary-color);
    background-color: #dbeafe;
}

.option-btn.correct {
    border-color: var(--success-color);
    background-color: #d1fae5;
    color: var(--success-color);
}

.option-btn.incorrect {
    border-color: var(--error-color);
    background-color: #fee2e2;
    color: var(--error-color);
}

.option-btn:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

/* 模式选择按钮 */
.mode-btn {
    padding: 24px;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    border: 2px solid transparent;
}

.mode-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px -8px rgba(0, 0, 0, 0.2);
}

/* 进度条 */
.progress-bar {
    width: 100%;
    height: 8px;
    background-color: #e5e7eb;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
    border-radius: 4px;
}

/* 单词显示区域 */
#wordDisplay {
    min-height: 120px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

#wordContent {
    line-height: 1.2;
    margin-bottom: 8px;
}

#wordPhonetic {
    font-family: 'Courier New', monospace;
    font-style: italic;
}

/* 反馈区域 */
#feedback {
    border-radius: 12px;
    margin: 20px 0;
}

.feedback-correct {
    background-color: #d1fae5 !important;
    border: 2px solid var(--success-color) !important;
    color: var(--success-color) !important;
}

.feedback-incorrect {
    background-color: #fee2e2 !important;
    border: 2px solid var(--error-color) !important;
    color: var(--error-color) !important;
}

/* 统计卡片 */
.stat-card {
    background: white;
    padding: 20px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
}

.stat-icon {
    font-size: 2rem;
    margin-bottom: 8px;
}

.stat-number {
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.875rem;
    color: #6b7280;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 16px;
    }
    
    #wordContent {
        font-size: 2rem;
    }
    
    .option-btn {
        padding: 12px;
        font-size: 0.9rem;
    }
    
    .mode-btn {
        padding: 16px;
    }
    
    .stat-card {
        padding: 16px;
    }
    
    .stat-icon {
        font-size: 1.5rem;
    }
    
    .stat-number {
        font-size: 1.5rem;
    }
}

/* 加载动画 */
.loading-spinner {
    border: 4px solid #f3f4f6;
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 输入框样式 */
.input-field {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.2s ease;
}

.input-field:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* 提示信息样式 */
.alert {
    padding: 12px 16px;
    border-radius: 8px;
    margin: 16px 0;
    display: flex;
    align-items: center;
}

.alert-error {
    background-color: #fee2e2;
    border: 1px solid #fecaca;
    color: var(--error-color);
}

.alert-warning {
    background-color: #fef3c7;
    border: 1px solid #fde68a;
    color: var(--warning-color);
}

.alert-success {
    background-color: #d1fae5;
    border: 1px solid #a7f3d0;
    color: var(--success-color);
}

.alert-info {
    background-color: #dbeafe;
    border: 1px solid #bfdbfe;
    color: var(--primary-color);
}

/* 隐藏类 */
.hidden {
    display: none !important;
}

/* 可见性切换 */
.invisible {
    visibility: hidden;
}

.visible {
    visibility: visible;
}

/* 文本样式 */
.text-gradient {
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* 阴影效果 */
.shadow-custom {
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.shadow-hover {
    transition: box-shadow 0.3s ease;
}

.shadow-hover:hover {
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}