fix(frontend): mobile layout for intro strip, info tips and card headers

- IconStepStrip stays a compact horizontal row on narrow screens (smaller
  tiles, label under icon, horizontal chevrons)
- tip-card-head stacks top-to-bottom with a smaller illustration
- InfoTip clamps to the viewport (collision padding clears the sticky
  header, flips below when no room above, max-height scroll)
- card headers wrap on narrow screens; security subtitle gets its own line

frontend/src/components/InfoTip.jsx

@@ -1,6 +1,7 @@
 import { useRef, useState } from 'react';
 import { Info } from 'lucide-react';
 import { Popover, PopoverTrigger, PopoverContent } from '@/components/ui/popover';
+import useMediaQuery from '../hooks/useMediaQuery';
 import { t } from '../i18n/t';
 
 // An (i) button that holds the explanation a page used to print inline.
@@ -9,6 +10,9 @@ import { t } from '../i18n/t';
 // (no button-in-button) and above Modal/Sheet (.info-tip__panel z-index).
 export default function InfoTip({ children, label, side = 'top', size = 'sm', className = '' }) {
     const [open, setOpen] = useState(false);
+    // Narrow screens: keep the panel clear of the sticky app header.
+    const narrow = useMediaQuery('(max-width: 640px)');
+    const collisionPadding = narrow ? { top: 72, right: 12, bottom: 12, left: 12 } : 8; // geometry: header 56px + safe area
     const pinned = useRef(false);
     const hoverable = (e) => e.pointerType === 'mouse';
 
@@ -37,6 +41,8 @@ export default function InfoTip({ children, label, side = 'top', size = 'sm', cl
             </PopoverTrigger>
             <PopoverContent
                 side={side}
+                avoidCollisions
+                collisionPadding={collisionPadding}
                 className="info-tip__panel"
                 onOpenAutoFocus={(e) => e.preventDefault()}
                 onCloseAutoFocus={(e) => e.preventDefault()}

frontend/src/styles/components/_cards.scss

@@ -15,6 +15,14 @@
 .card-header {
     @include flex-between();
     margin-bottom: $space-4;
+
+    // Narrow: title takes the row, trailing chips/actions wrap below.
+    @include respond-to($breakpoint-sm) {
+        flex-wrap: wrap;
+        gap: $space-2;
+
+        > h3 { flex: 1 1 auto; min-width: 0; }
+    }
 }
 
 .card h3 {

frontend/src/styles/components/_info-tip.scss

@@ -31,6 +31,8 @@
     z-index: $z-tooltip + 10;
     width: auto;
     max-width: min(320px, calc(100vw - 24px));
+    max-height: var(--radix-popover-content-available-height, 60vh);
+    overflow-y: auto;
     padding: $space-2 $space-3;
     font-size: $text-sm;
     font-weight: $font-weight-normal;
@@ -94,11 +96,32 @@
         svg { width: 16px; height: 16px; } // geometry: connector icon
     }
 
+    // Narrow: stay one compact row; label sits under a smaller tile.
     @include respond-to($breakpoint-sm) {
-        flex-direction: column;
+        flex-wrap: wrap;
         align-items: flex-start;
+        gap: $space-1;
 
-        &__arrow { transform: rotate(90deg); margin-inline-start: $space-3; }
+        &__step {
+            display: grid;
+            grid-template-columns: auto auto;
+            justify-content: center;
+            align-items: center;
+            gap: $space-1;
+        }
+
+        &__tile {
+            grid-column: 1 / -1;
+            justify-self: center;
+            width: 36px;  // geometry: compact tile
+            height: 36px; // geometry: compact tile
+            svg { width: 18px; height: 18px; } // geometry: icon in compact tile
+        }
+
+        &__label { font-size: $text-xs; }
+
+        // Centre the 14px chevron on the 36px tile.
+        &__arrow { margin-block-start: 11px; svg { width: 14px; height: 14px; } } // geometry: connector
     }
 }
 
@@ -177,6 +200,19 @@
     gap: $space-3;
 
     &__text { flex: 1; min-width: 0; }
+
+    @include respond-to($breakpoint-sm) {
+        flex-direction: column;
+        align-items: flex-start;
+        gap: $space-2;
+
+        .tip-illustration {
+            width: 36px;  // geometry: compact illustration
+            height: 36px; // geometry: compact illustration
+        }
+
+        &__text { flex: none; width: 100%; }
+    }
     &__title { display: flex; align-items: center; gap: $space-1; color: $text-primary; font-weight: $font-weight-medium; }
     &__line { margin: 0; color: $text-secondary; font-size: $text-sm; }
 }

frontend/src/styles/pages/_security.scss

@@ -66,6 +66,8 @@
         font-weight: $font-weight-medium;
         color: var(--text-faint);
         letter-spacing: 0;
+
+        @include respond-to($breakpoint-sm) { display: block; }
     }
 
     // Severity / state chip (mono uppercase on a semantic wash) —