Starting an Institut Pasteur branded base theme

basetheme_bootstrap/static/css/basetheme_bootstrap4_pasteur.css

+.fork_me{
+    font-family: tahoma;
+    font-size: 20px;
+    position:fixed;
+    top:75px;
+    right:-55px;
+    display:block;
+    -webkit-transform: rotate(45deg);
+    -moz-transform: rotate(45deg);
+    background-color:#c5b1e7;
+    color:black;
+    padding: 4px 60px 4px 60px;
+    z-index:99;
+}
+.bd-placeholder-img {
+    font-size: 1.125rem;
+    text-anchor: middle;
+    -webkit-user-select: none;
+    -moz-user-select: none;
+    -ms-user-select: none;
+    user-select: none;
+}
+
+@media (min-width: 768px) {
+    .bd-placeholder-img-lg {
+        font-size: 3.5rem;
+    }
+}
+
+body {
+    padding-top: 3.5rem;
+}
+
+.footer {
+  background-color: #f5f5f5;
+}
+@media (min-width: 1600px){
+    .container {
+        max-width: 1530px;
+    }
+}
+@media (min-width: 1920px){
+    .container {
+        max-width: 1830px;
+    }
+}
+@media (min-width: 2560px){
+    .container {
+        max-width: 2490px;
+    }
+}
+.content-page-title>*:first-child{
+    flex-grow: 1;
+}
+.content-page-title{
+    display:flex;
+}
+body{
+    background:green;
+}
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