Improve flash messages

public/css/style.css

@@ -37,7 +37,6 @@
   --color-flash-notice-background: #294e43;
   --color-flash-error-background: #2c4647;
   --color-flash-error-border: #e6afa2;
-  --flash-space: 6rem;
 
   /* Ombres */
   --color-shadow-light: rgb(202 210 197 / 20%);
@@ -558,17 +557,10 @@ summary:focus-visible {
 /* Notifications
 ------------------------------------------------------------------------ */
 
-main.main--with-flash {
-  position: relative;
-}
-
 .flash-container {
-  position: absolute;
-  z-index: 1;
-  inset: 0 0 auto;
   display: grid;
   gap: 10px;
-  padding: 20px;
+  margin-block: 1.5rem;
 }
 
 .flash {
@@ -591,15 +583,6 @@ main.main--with-flash {
   color: var(--color-text);
 }
 
-main.main--with-flash > section:first-of-type {
-  padding-top: var(--flash-space);
-}
-
-main.main--with-flash > section.page-section:first-of-type {
-  padding-top:
-    calc(var(--flash-space) + clamp(24px, 5vw, 72px));
-}
-
 /* Tableaux
 ------------------------------------------------------------------------ */
 
@@ -685,10 +668,6 @@ footer {
 ------------------------------------------------------------------------ */
 
 @media screen and (max-width: 600px) {
-  :root {
-    --flash-space: 8rem;
-  }
-
   .box {
     margin-top: 60px;
     padding: 20px;