Move inline styles to CSS classes; update README

Extract repeated inline styles from templates into named CSS classes in
base.html: layout helpers, buttons, form groups, alert boxes, results table
rules, row highlight classes, typography utilities, and empty-state styles.
Remove the per-page <style> block from results.html.

Update README to reflect current destinations, GraphQL data source, Circle
Line timetable, configurable connection range, and GWR fare table.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/index.html

@@ -1,9 +1,9 @@
 {% extends "base.html" %}
 {% block content %}
 <div class="card">
-  <h2 style="margin-top:0">Plan your journey</h2>
+  <h2>Plan your journey</h2>
   <form method="get" action="{{ url_for('search') }}">
-    <div style="margin-bottom:1.2rem">
+    <div class="form-group">
       <span class="field-label">Departure point</span>
       <div class="fixed-station" aria-label="Departure point">
         <strong>Bristol Temple Meads</strong>
@@ -11,7 +11,7 @@
       </div>
     </div>
 
-    <div style="margin-bottom:1.2rem">
+    <div class="form-group">
       <span class="field-label">Eurostar destination</span>
       <div class="destination-grid" role="radiogroup" aria-label="Eurostar destination">
         {% for slug, name in destinations.items() %}
@@ -33,7 +33,7 @@
       </div>
     </div>
 
-    <div style="margin-bottom:1.5rem">
+    <div class="form-group-lg">
       <label for="travel_date" class="field-label">
         Travel date
       </label>
@@ -42,7 +42,7 @@
         class="form-control">
     </div>
 
-    <div style="margin-bottom:1.2rem">
+    <div class="form-group">
       <label for="min_connection" class="field-label">
         Minimum connection time (Paddington &rarr; St&nbsp;Pancras)
       </label>
@@ -53,7 +53,7 @@
       </select>
     </div>
 
-    <div style="margin-bottom:1.5rem">
+    <div class="form-group-lg">
       <label for="max_connection" class="field-label">
         Maximum connection time (Paddington &rarr; St&nbsp;Pancras)
       </label>
@@ -64,9 +64,7 @@
       </select>
     </div>
 
-    <button type="submit"
-      style="background:#00539f;color:#fff;border:none;padding:0.75rem 2rem;
-             font-size:1rem;font-weight:600;border-radius:4px;cursor:pointer">
+    <button type="submit" class="btn-primary">
       Search journeys
     </button>
   </form>