[Style] Change button design

@@ -18,3 +18,31 @@ h2 {
   flex: 1;
   display: flex;
 }
+
+button {
+  cursor: pointer;
+  background-color: white;
+  color: black;
+  border: solid thin;
+  border-color: lavender;
+  border-radius: 3px;
+}
+
+button {
+  -webkit-transition-duration: 0.4s; /* Safari */
+  transition-duration: 0.4s;
+}
+
+button:hover:not(:disabled) {
+  background-color: rgba(39, 197, 250, 0.334);
+  color: white;
+}
+
+button:active:not(:disabled) {
+  background-color: rgba(39, 197, 250, 0.548);
+}
+
+button:disabled {
+  cursor: auto;
+  color: rgb(209, 209, 209);
+}

@@ -26,6 +26,7 @@ header {
 .hcb {
   height: 34px;
   margin: 10px;
+  font-size: medium;
 }
 
 .hcd {
@@ -33,6 +34,7 @@ header {
 }
 
 .hcd > button {
+  border-radius: 0;
   font-size: large;
 }
 
@@ -47,6 +49,7 @@ header {
 }
 
 .hrd > button {
+  border-radius: 0;
   padding: 8px 14px 8px 14px;
   font-size: medium;
 }

@@ -11,9 +11,14 @@ aside {
 }
 
 .ssc {
+  cursor: pointer;
   height: 15px;
   width: 15px;
   margin: 5px 10px 5px 5px;
   border: solid thin grey;
   border-radius: 3px;
 }
+
+.SideSubject > span {
+  line-height: 25px;
+}