body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #0f0f12;
    color: #d0d0d0;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    border: 1px solid #00a8ff55;
}

header {
    text-align: center;
    margin-bottom: 30px;
    border-bottom: 1px solid #00a8ff33;
    padding-bottom: 15px;
}

h1 {
    color: #00a8ff;
    text-shadow: 0 0 10px rgba(0, 168, 255, 0.3);
}

.difficulty-tag {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 3px;
    font-size: 0.7em;
    margin-left: 10px;
}

.easy { 
    background-color: #4caf50; 
    color: white; 
}

.hard { 
    background-color: #f44336; 
    color: white; 
}

.question {
    background-color: rgba(255, 255, 255, 0.03);
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 10px;
    border-left: 4px solid #00a8ff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

.options {
    margin-top: 15px;
    display: grid;
    gap: 10px;
}

.option-btn {
    padding: 12px 15px;
    background-color: #2c3e50;
    color: #ecf0f1;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    text-align: left;
    transition: all 0.2s;
    border: 1px solid #34495e;
}

.option-btn:hover {
    background-color: #34495e;
    transform: translateY(-1px);
}

.option-btn.selected {
    background-color: #007acc;
    border-color: #00a8ff;
}

.option-btn.correct {
    background-color: #2e7d32;
    border-color: #4caf50;
}

.option-btn.incorrect {
    background-color: #c62828;
    border-color: #f44336;
}

#submit-container {
    text-align: center;
    margin: 30px 0;
}

#submit-btn {
    padding: 12px 40px;
    background-color: #007acc;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 1em;
    cursor: pointer;
    transition: background 0.2s;
    margin-right: 10px;
}

#submit-btn:hover {
    background-color: #005a99;
}

#reset-btn {
    padding: 12px 40px;
    background-color: #6c757d;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 1em;
    cursor: pointer;
    transition: background 0.2s;
}

#reset-btn:hover {
    background-color: #545b62;
}

#result-message {
    text-align: center;
    font-size: 1.1em;
    font-weight: bold;
    margin: 20px 0;
    padding: 15px;
    border-radius: 5px;
    display: none;
}

.success-msg {
    background-color: #1b5e20;
    color: #a5d6a7;
    border: 1px solid #4caf50;
}

.fail-msg {
    background-color: #b71c1c;
    color: #ef9a9a;
    border: 1px solid #f44336;
}

#key-section {
    display: none;
    text-align: center;
    padding: 20px;
    background-color: #000;
    border: 1px solid #00a8ff;
    border-radius: 10px;
    margin-top: 20px;
    box-shadow: 0 0 20px rgba(0, 168, 255, 0.1);
}

#bsod-code-display {
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 1.5em;
    color: #00ff00;
    background-color: #000;
    padding: 20px;
    margin-top: 15px;
    border-radius: 5px;
    letter-spacing: 2px;
    min-height: 30px;
    text-shadow: 0 0 10px rgba(0, 255, 0, 0.5);
}

/* 复制按钮样式 */
#copy-btn {
    margin-top: 15px;
    padding: 10px 20px;
    background-color: #28a745;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9em;
    display: none; /* 初始隐藏，生成卡密后才显示 */
}

#copy-btn:hover {
    background-color: #218838;
}

#copy-btn.copied {
    background-color: #17a2b8;
}

/* 动画效果 */
@keyframes glow {
    0%, 100% { 
        text-shadow: 0 0 5px #00ff00; 
    }
    50% { 
        text-shadow: 0 0 20px #00ff00, 0 0 30px #00ff00; 
    }
}