fix topic

@@ -89,6 +89,9 @@ export default {
   activated() {
     if (this.scrollTop && this.yoho.direction === 'back') {
       this.$refs.scroll.$el.scrollTop = this.scrollTop;
+    } else {
+      this.updateHeadAnimateStep(0);
+      this.scrollTop = 0;
     }
 
     if (+this.$route.params.topicId !== this.topicId) {
@@ -145,7 +148,7 @@ export default {
       return this.topicName || this.topicSimpleInfo.topicName || '';
     },
     tabBlockSuctionTop() {
-      return this.scrollTop >= (this._topicHeaderHeight - this._headerHeight);
+      return this.scrollTop > (this._topicHeaderHeight - this._headerHeight);
     },
     headerBgOpacity() {
       return this.headerAnimateStep / 100;
@@ -188,13 +191,13 @@ export default {
       this._topicHeaderHeight = this._topicHeaderHeight || this.$refs.topicBanner.$el.offsetHeight;
 
       let step = Math.round((scrollTop - 4) / (this._topicHeaderHeight - this._headerHeight - 10) * 100);
-      if (step) {
-        this.headerAnimateStep = Math.max(Math.min(step, 100), 0);
 
-        this.SET_STATUS_BAR_COLOR({
-          color: this.headerAnimateStep > 55 ? 'black' : 'white'
-        });
-      }
+      this.headerAnimateStep = Math.max(Math.min(step, 100), 0);
+      this.SET_STATUS_BAR_COLOR({
+        color: this.headerAnimateStep > 55 ? 'black' : 'white'
+      });
+
+      console.log(this.headerAnimateStep);
     },
     onDounceScroll({items}) {
       this.reportArticleShow(items);