/* 通用样式 */
body {
    font-family: "Microsoft YaHei";
    background: #f5f7fa;
    color: #333;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
}

/* 标题 */
h1 {
    margin-bottom: 20px;
    color: #2c3e50;
    font-size: 2rem;
}

/* 主容器 */
.container {
    background: #fff;
    border-radius: 16px;
    padding: 30px;
    width: 90%;
    max-width: 500px;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.15);
    text-align: center;
}

/* GitHub 图标 */
.github-icon {
    width: 28px;
    height: 28px;
    margin-left: 10px;
    vertical-align: middle;
    filter: invert(20%) sepia(10%) saturate(0%) hue-rotate(180deg)
        brightness(0.8);
    transition: transform 0.2s ease, filter 0.2s ease;
}

.github-icon:hover {
    transform: scale(1.1);
    filter: invert(0%) sepia(100%) saturate(0%) hue-rotate(0deg) brightness(0.4);
}

/* 下拉菜单 */
#category-select {
    font-size: 1rem;
    padding: 8px 12px;
    border-radius: 8px;
    border: 1px solid #ccc;
    margin-bottom: 20px;
    width: 100%;
    max-width: 300px;
}

/* 提示示例 */
.hint {
    margin: 10px 0 20px;
    font-size: 0.8rem;
    color: #555;
    background: #eef5ff;
    padding: 8px 12px;
    border-left: 4px solid #3498db;
    border-radius: 6px;
    text-align: left;
}

/* 题目显示 */
.question {
    font-size: 1.3rem;
    margin: 20px 0;
    padding: 10px;
    font-weight: bold;
    color: #34495e;
}

/* 输入框 */
#answer-input {
    width: 100%;
    max-width: 300px;
    padding: 10px;
    font-size: 1rem;
    border-radius: 8px;
    border: 1px solid #bbb;
    outline: none;
    transition: border-color 0.2s ease-in-out;
}

#answer-input:focus {
    border-color: #3498db;
    box-shadow: 0 0 5px rgba(52, 152, 219, 0.4);
}

/* 反馈信息 */
#feedback {
    margin-top: 15px;
    font-size: 1.1rem;
    font-weight: bold;
}

#feedback.correct {
    color: #27ae60;
}

#feedback.wrong {
    color: #e74c3c;
}

/* 按钮 */
button {
    margin-top: 15px;
    padding: 8px 16px;
    font-size: 1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    background: #3498db;
    color: white;
    transition: background 0.2s;
}

button:hover {
    background: #2980b9;
}