style(create-trip): improve layout and responsiveness

Author: earzalien

client/src/pages/styles/CreateTrip.css

@@ -77,8 +77,11 @@
   background-color: #ffffff;
   padding: 2rem;
   box-shadow: 0 4px 15px rgba(0, 0, 0, 0.03);
+  transition: box-shadow 0.3s ease;
+}
+.create-trip-form:hover {
+  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.06);
 }
-
 .form-group {
   display: flex;
   flex-direction: column;
@@ -175,27 +178,20 @@
   flex: 1;
 }
 
-#start-date {
-  color: #999;
-}
-
-#end-date {
-  color: #999;
+input[type="date"]:not(:placeholder-shown) {
+  color: var(--black);
 }
 
 .astuces-container {
-  display: flex;
-  justify-content: center;
-  align-items: center;
-  width: 25vw;
-  height: 9vh;
+  width: 100%;
+  max-width: 480px;
   background-color: rgba(217, 217, 217, 0.3);
   border: 1px solid rgba(217, 217, 217, 0.5);
   border-radius: 8px;
   padding: 1rem;
-  margin-top: 2.5rem;
+  margin-top: 2rem;
   font-family: var(--body-text);
-  font-size: 1rem;
+  font-size: 0.95rem;
   color: var(--black);
   text-align: center;
 }
@@ -218,6 +214,8 @@
   cursor: pointer;
   border: none;
   transition: all 0.2s ease;
+  flex: 1;
+  max-width: 200px;
 }
 
 .button-container button[type="submit"] {