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

body {
    font-family: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    min-height: 100vh;
    color: #333;
    background: #f8f9fa;
}

/* 应用容器 */
.app-container {
    min-height: 100vh;
    position: relative;
    overflow: hidden;
}

/* 主屏幕样式 - 蓝白分界背景 */
#start-screen {
    min-height: 100vh;
    position: relative;
    background: linear-gradient(135deg, 
        transparent 0%, 
        transparent 45%, 
        #4285f4 45%, 
        #4285f4 100%
    );
    background-color: white;
}

#start-screen::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(65deg, 
        #ffffff 0%, 
        #ffffff 45%, 
        #1a73e8 45%, 
        #1a73e8 100%
    );
    z-index: 0;
}

/* 主布局 */
.main-layout {
    position: relative;
    z-index: 1;
    display: flex;
    min-height: 100vh;
    align-items: center;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
}

/* Logo区域 */
.logo-section {
    flex: 0 0 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-right: 200px;
}

.logo-image {
    max-width: 100%;
    max-height: 400px;
    width: auto;
    height: auto;
    object-fit: contain;
    filter: drop-shadow(0 10px 20px rgba(0, 0, 0, 0.1));
}

/* 内容区域 */
.content-section {
    flex: 0 0 50%;
    padding-left: 150px;
    color: white;
}

.intro-content h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 30px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    line-height: 1.2;
}

.intro-content > p {
    font-size: 1.5rem;
    margin-bottom: 30px;
    opacity: 0.95;
    line-height: 1.5;
}

/* 按钮样式 */
.btn {
    padding: 18px 36px;
    border: none;
    border-radius: 30px;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    min-width: 160px;
    font-family: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

.btn-primary {
    background: linear-gradient(45deg, #ffffff, #f0f8ff);
    color: #1a73e8;
    border: 2px solid #1b71f9;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(255, 255, 255, 0.6);
    background: #ffffff;
}

.btn-secondary {
    background: #1a73e8;
    color: white;
    border: 2px solid #1a73e8;
}

.btn-secondary:hover {
    background: #1557b0;
    border-color: #1557b0;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(26, 115, 232, 0.4);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* 通用屏幕样式 */
.screen {
    display: none;
}

.screen.active {
    display: block;
}

/* 游戏和结果页面容器 */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 40px;
    min-height: 100vh;
    background: white;
}

/* 游戏屏幕样式 */
#game-screen {
    background: linear-gradient(135deg, #f0f8ff 0%, #e3f2fd 100%);
}

.game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    padding: 25px 30px;
    background: white;
    border-radius: 20px;
    box-shadow: 0 5px 20px rgba(26, 115, 232, 0.1);
}

.progress {
    font-size: 1.3rem;
    font-weight: 700;
    color: #1a73e8;
}

.score-display {
    font-size: 1.2rem;
    color: #1a73e8;
    font-weight: 600;
}

.question-container {
    margin-bottom: 40px;
    background: white;
    padding: 40px;
    border-radius: 20px;
    box-shadow: 0 5px 20px rgba(26, 115, 232, 0.1);
}

.question-container h3 {
    font-size: 1.5rem;
    margin-bottom: 30px;
    color: #333;
    line-height: 1.6;
    font-weight: 600;
}

.question-header {
    margin-bottom: 20px;
    text-align: left;
}

.difficulty-badge {
    display: inline-block;
    padding: 6px 15px;
    border-radius: 25px;
    font-size: 0.9rem;
    font-weight: 600;
    color: white;
    margin-bottom: 15px;
}

.difficulty-badge.easy {
    background: linear-gradient(45deg, #4caf50, #66bb6a);
}

.difficulty-badge.medium {
    background: linear-gradient(45deg, #ff9800, #ffb74d);
    color: #fff;
}

.difficulty-badge.hard {
    background: linear-gradient(45deg, #f44336, #e57373);
}

.question-content {
    font-size: 1.5rem;
    line-height: 1.6;
    color: #333;
}

.options {
    display: grid;
    gap: 15px;
    margin-bottom: 20px;
}

.option {
    padding: 20px 25px;
    border: 2px solid #e8f0fe;
    border-radius: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: left;
    background: #fafbff;
    position: relative;
    user-select: none;
}

.option:hover {
    border-color: #4285f4;
    background: #e8f0fe;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(66, 133, 244, 0.2);
}

.option.selected {
    border-color: #1a73e8;
    background: #e8f0fe;
}

.option.correct {
    border-color: #34a853;
    background: #e8f5e8;
}

.option.incorrect {
    border-color: #ea4335;
    background: #fce8e6;
}

.option input[type="radio"] {
    margin-right: 12px;
    transform: scale(1.3);
    cursor: pointer;
    accent-color: #1a73e8;
}

.option label {
    cursor: pointer;
    flex: 1;
    margin-left: 5px;
    font-size: 1.1rem;
    line-height: 1.4;
}

.game-controls {
    text-align: center;
}

/* 结果页面样式 */
#result-screen {
    background: linear-gradient(135deg, #e8f0fe 0%, #f0f8ff 100%);
}

.result-content h2 {
    font-size: 2.5rem;
    margin-bottom: 40px;
    color: #1a73e8;
    font-weight: 700;
}

.final-score {
    margin-bottom: 50px;
    text-align: center;
}

.final-score h3 {
    font-size: 1.4rem;
    color: #666;
}

.score-number {
    font-size: 5rem;
    font-weight: 800;
    background: linear-gradient(45deg, #1a73e8, #4285f4);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 15px;
}

.score-text {
    font-size: 1.3rem;
    color: #666;
    font-weight: 500;
}

.score-breakdown {
    margin-bottom: 50px;
    text-align: left;
}

.score-breakdown h4 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: #333;
    font-weight: 600;
}

.breakdown-item {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 20px 0;
    border-bottom: 1px solid #e8f0fe;
}

.breakdown-item:last-child {
    border-bottom: none;
}

.question-result {
    flex: 1;
    text-align: left;
}

.result-icon {
    font-size: 1.3rem;
    margin-right: 12px;
}

.result-details {
    text-align: right;
    min-width: 120px;
}

.correct-answer {
    font-size: 0.9rem;
    color: #34a853;
    font-weight: 600;
    margin-top: 8px;
    padding: 5px 12px;
    background: #e8f5e8;
    border-radius: 15px;
    display: inline-block;
}

.explanation {
    font-size: 0.9rem;
    color: #666;
    margin-top: 8px;
    padding: 8px 12px;
    background: #f8f9fa;
    border-radius: 10px;
    border-left: 3px solid #1a73e8;
    line-height: 1.4;
}

.correct-icon {
    color: #34a853;
}

.incorrect-icon {
    color: #ea4335;
}

.result-actions {
    display: flex;
    justify-content: center;
    gap: 25px;
    flex-wrap: wrap;
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .main-layout {
        flex-direction: column;
        padding: 20px;
        text-align: center;
    }
    
    .logo-section, .content-section {
        flex: none;
        width: 100%;
        padding: 0;
    }
    
    .logo-section {
        margin-bottom: 40px;
    }
    
    .logo-image {
        max-height: 200px;
    }
    
    .intro-content h1 {
        font-size: 2.5rem;
    }
    
    #start-screen::before {
        background: linear-gradient(180deg, 
            #ffffff 0%, 
            #ffffff 50%, 
            #1a73e8 50%, 
            #1a73e8 100%
        );
    }
}

@media (max-width: 768px) {
    .main-layout {
        padding: 15px;
    }
    
    .container {
        padding: 20px 15px;
    }
    
    .intro-content h1 {
        font-size: 2rem;
    }
    
    .intro-content > p {
        font-size: 1.1rem;
    }
    
    .intro-description h2 {
        font-size: 1.5rem;
    }
    
    .game-header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
    
    .question-container {
        padding: 25px 20px;
    }
    
    .question-container h3 {
        font-size: 1.3rem;
    }
    
    .option {
        padding: 15px 20px;
    }
    
    .option label {
        font-size: 1rem;
    }
    
    .score-number {
        font-size: 4rem;
    }
    
    .result-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 300px;
        margin: 5px 0;
    }
    
    .logo-image {
        max-height: 150px;
    }
}

@media (max-width: 480px) {
    .intro-content h1 {
        font-size: 1.8rem;
    }
    
    .question-container h3 {
        font-size: 1.2rem;
    }
    
    .score-number {
        font-size: 3.5rem;
    }
}