fix: 修正修改测试时选择框不会自动聚焦到正确值的问题

src/components/Basic/CSelect.vue

@@ -1,6 +1,6 @@
 <template>
   <component :class="value === '' && 'unfilled'" :is="'select'" :value="value" @change="$emit('input', $event.target.value)">
-    <option disabled :value="''" selected>{{disabledDisplay}}</option>
+    <option disabled :selected="value === ''" :value="''">{{disabledDisplay}}</option>
     <option v-for="item in list" :value="item.value" :key="item.value">
       {{ item.display }}
     </option>

src/views/quiz/components/QuizDetailFactory.vue

@@ -64,7 +64,7 @@ export default {
   align-items: center;
   color: $theme-blue;
   padding: 6px 8px;
-  margin: 0 -8px;
+  margin: 16px -8px;
   background-color: $theme-blue-transparent;
 }
 </style>

src/views/student/components/StudentQuizDetail.vue

@@ -2,7 +2,7 @@
   <div class="student-quiz-detail">
     <back-title>{{quiz.name}}</back-title>
     <router-link v-if="quiz.state === QuizState.ongoing" :to="{ name: 'student-do-quiz', params: { quizId: quiz.id}}">
-      <c-button class="mb-16" theme="green" icon="edit" block>做题</c-button>
+      <c-button class="mb-16" theme="green" icon="edit">开始做题</c-button>
     </router-link>
     <quiz-detail-factory :quiz-detail="quiz" />
   </div>
@@ -50,7 +50,7 @@ export default {
 <style lang="scss" scoped>
 .student-quiz-detail {
   margin: 0 auto;
-  max-width: 1000px;
+  max-width: 600px;
   padding: 64px 24px;
 }
 </style>