diff --git a/TC1/http_server/index.html b/TC1/http_server/index.html
index c3cf9de..bad99da 100644
--- a/TC1/http_server/index.html
+++ b/TC1/http_server/index.html
@@ -219,7 +219,7 @@ HttpGet("/status", function (re) {
 
 var first_load_power = true;
 var power_idx = 1;
-var position = 10;
+var position = 0;
 function GetPowerRecord() {
     HttpPost("/power", function (re) {
         var power = JSON.parse(re);
@@ -227,7 +227,7 @@ function GetPowerRecord() {
         var html = "";
         for (var i = 0; i < power.powers.length; i++) {
             html += "<div class='power_pre' style='height:"+power.powers[i]+"px;left:"+position+"px;'></div>";
-            position += 10;
+            position += 3;
         }
         if (power.powers.length != 0) {
             power_line.innerHTML += html;
diff --git a/TC1/user_power.c b/TC1/user_power.c
index b11ed7e..369e9a8 100644
--- a/TC1/user_power.c
+++ b/TC1/user_power.c
@@ -38,7 +38,8 @@ char* GetPowerRecord(int idx)
 {
     if (idx > power_record.idx) return "";
 
-    int i = idx > 0 ? idx : (power_record.idx - PW_NUM - 1);
+    int i = idx > 0 ? idx : (power_record.idx - PW_NUM + 1);
+    i = i < 0 ? 0 : i;
     char* tmp = power_record_str;
     for (; i <= power_record.idx; i++)
     {