完成上传页面主要逻辑，网络问题仍未解决

src/App.css

@@ -6,10 +6,19 @@ a.btn {
   border-radius: .5rem;
   padding: .375rem 1.75rem;
   font-size: 1.1rem;
+  cursor: pointer;
+  transition: filter .3s ease-out;
+}
+.btn:disabled {
+  cursor: not-allowed;
+  filter: grayscale(100%);
 }
 .btn:active {
   color: white !important;
 }
+.btn:hover {
+  filter: brightness(1.2);
+}
 
 button.btn {
   border: none;
@@ -17,4 +26,18 @@ button.btn {
 
 .btn-primary {
   background-color: #318ffb;
+}
+.btn-ok {
+  background-color: #47c74c;
+}
+.btn-gray {
+  background-color: #d9d9d9;
+}
+
+.btn-circle {
+  border-radius: 50%;
+  width: 40px;
+  height: 40px;
+  padding: 8px;
+  box-shadow: 1px 1px 4px 0 #0003;
 }