* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: "微软雅黑", sans-serif;
    background: #f5f7fa;
    padding: 20px;
}
.container {
    max-width: 880px;
    margin: 0 auto;
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}
h1 {
    text-align: center;
    margin-bottom: 10px;
}
.desc {
    text-align: center;
    color: #666;
    margin-bottom: 20px;
}
.select-box {
    text-align: center;
    margin-bottom: 20px;
}
.select-box select {
    padding: 6px 12px;
    border-radius: 6px;
    border: 1px solid #ccc;
}
.tab-wrap {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}
.tab {
    flex: 1;
    padding: 12px;
    text-align: center;
    background: #f0f0f0;
    border-radius: 8px;
    cursor: pointer;
}
.tab.active {
    background: #1677ff;
    color: #fff;
}
.content {
    margin-bottom: 20px;
}
.hide {
    display: none;
}
.opt-item {
    display: block;
    width: 100%;
    padding: 12px;
    margin: 8px 0;
    border: 1px solid #ddd;
    border-radius: 6px;
    cursor: pointer;
    background: #fff;
    text-align: left;
}
.opt-item.active {
    background: #1677ff;
    color: #fff;
}
.ans-explain {
    margin-top: 15px;
    padding: 12px;
    border-radius: 6px;
    display: none;
}
.correct {
    background: #e6f7ef;
    color: #065f46;
}
.wrong {
    background: #fef2f2;
    color: #b91c1c;
}
.btn-group {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
}
.bottom-btn {
    margin-top: 30px;
}
button {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    background: #1677ff;
    color: #fff;
    cursor: pointer;
}
.score-btn {
    background: #00b42a;
}
.reset-btn {
    background: #666;
}
.result-box {
    padding: 20px;
    background: #f0f7ff;
    border-radius: 8px;
    margin-top: 20px;
}
.case-text {
    width: 100%;
    height: 120px;
    margin-top: 10px;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
}