css: standardize width of fixed width pages.

Standardize various width-limited pages to 70em width.

app/javascript/src/styles/base/020_base.scss

@@ -119,3 +119,7 @@ table tfoot {
   font-style: italic;
   font-size: 0.8em;
 }
+
+.fixed-width-container {
+  max-width: 70em;
+}

app/javascript/src/styles/specific/maintenance.scss

@@ -1,5 +0,0 @@
-div#c-maintenance-user-login-reminders {
-  div#a-new {
-    width: 50em;
-  }
-}

app/javascript/src/styles/specific/site_map.scss

@@ -2,11 +2,10 @@
 
 div#c-static {
   div#a-site-map {
-    width: 80em;
+    display: flex;
 
     section {
-      width: 20em;
-      float: left;
+      flex: 1;
 
       h1 {
         font-size: $h3_size;

app/javascript/src/styles/specific/tags.scss

@@ -13,8 +13,6 @@ div#c-tags {
 }
 
 #tags-container {
-  max-width: 70em;
-
   div.header {
     margin: 0;
     display: grid;

app/javascript/src/styles/specific/terms_of_service.scss

@@ -1,8 +1,6 @@
 @import "../base/000_vars.scss";
 
 div#c-static div#a-terms-of-service {
-  width: 40em;
-
   h1 {
     font-size: $h2_size;
   }

app/javascript/src/styles/specific/user_feedback.scss

@@ -6,9 +6,4 @@ div#c-user-feedbacks, div#c-moderator-dashboards div#col2 {
   .feedback-category-negative {
     background: var(--error-background-color);
   }
-
-  #negative-policy {
-    max-width: 50em;
-    margin-bottom: 1em;
-  }
 }

app/javascript/src/styles/specific/user_upgrades.scss

@@ -1,8 +1,5 @@
 div#c-user-upgrades {
   div#a-new {
-    max-width: 40em;
-    font-size: 1.2em;
-
     form.stripe {
       display: inline;
     }

app/javascript/src/styles/specific/users.scss

@@ -54,13 +54,4 @@ div#c-users {
       color: var(--text-color);
     }
   }
-
-  div#a-new {
-    max-width: 60em;
-
-    p {
-      font-size: 1.2em;
-      line-height: 1.4em;
-    }
-  }
 }