diff --git a/web/src/lib/components/CourseDetail.svelte b/web/src/lib/components/CourseDetail.svelte
index 71082b5..172685f 100644
--- a/web/src/lib/components/CourseDetail.svelte
+++ b/web/src/lib/components/CourseDetail.svelte
@@ -9,6 +9,7 @@ import {
   isTimeTBA,
 } from "$lib/course";
 import { Tooltip } from "bits-ui";
+import SimpleTooltip from "./SimpleTooltip.svelte";
 import { Info, Copy, Check } from "@lucide/svelte";
 
 let { course }: { course: CourseResponse } = $props();
@@ -50,7 +51,8 @@ async function copyEmail(email: string, event: MouseEvent) {
                 </span>
               </Tooltip.Trigger>
               <Tooltip.Content
-                class="bg-card text-card-foreground text-xs border border-border rounded-md px-3 py-2 shadow-md max-w-72"
+                sideOffset={6}
+                class="z-50 bg-card text-card-foreground text-xs border border-border rounded-md px-3 py-2 shadow-md max-w-72"
               >
                 <div class="space-y-1.5">
                   <div class="font-medium">{instructor.displayName}</div>
@@ -134,16 +136,9 @@ async function copyEmail(email: string, event: MouseEvent) {
       <h4 class="text-sm text-foreground mb-2">
         <span class="inline-flex items-center gap-1">
           Delivery
-          <Tooltip.Root delayDuration={100}>
-            <Tooltip.Trigger>
-              <Info class="size-3 text-muted-foreground/50" />
-            </Tooltip.Trigger>
-            <Tooltip.Content
-              class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
-            >
-              How the course is taught: in-person, online, hybrid, etc.
-            </Tooltip.Content>
-          </Tooltip.Root>
+          <SimpleTooltip text="How the course is taught: in-person, online, hybrid, etc." delay={150} passthrough>
+            <Info class="size-3 text-muted-foreground/50" />
+          </SimpleTooltip>
         </span>
       </h4>
       <span class="text-foreground">
@@ -168,34 +163,20 @@ async function copyEmail(email: string, event: MouseEvent) {
         <h4 class="text-sm text-foreground mb-2">
           <span class="inline-flex items-center gap-1">
             Attributes
-            <Tooltip.Root delayDuration={100}>
-              <Tooltip.Trigger>
-                <Info class="size-3 text-muted-foreground/50" />
-              </Tooltip.Trigger>
-              <Tooltip.Content
-                class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
-              >
-                Course flags for degree requirements, core curriculum, or special designations
-              </Tooltip.Content>
-            </Tooltip.Root>
+            <SimpleTooltip text="Course flags for degree requirements, core curriculum, or special designations" delay={150} passthrough>
+              <Info class="size-3 text-muted-foreground/50" />
+            </SimpleTooltip>
           </span>
         </h4>
         <div class="flex flex-wrap gap-1.5">
           {#each course.attributes as attr}
-            <Tooltip.Root delayDuration={100}>
-              <Tooltip.Trigger>
-                <span
-                  class="inline-flex text-xs font-medium bg-card border border-border rounded-md px-2 py-0.5 text-muted-foreground hover:text-foreground hover:border-foreground/20 transition-colors"
-                >
-                  {attr}
-                </span>
-              </Tooltip.Trigger>
-              <Tooltip.Content
-                class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-64"
+            <SimpleTooltip text="Course attribute code" delay={150} passthrough>
+              <span
+                class="inline-flex text-xs font-medium bg-card border border-border rounded-md px-2 py-0.5 text-muted-foreground hover:text-foreground hover:border-foreground/20 transition-colors"
               >
-                Course attribute code
-              </Tooltip.Content>
-            </Tooltip.Root>
+                {attr}
+              </span>
+            </SimpleTooltip>
           {/each}
         </div>
       </div>
@@ -207,19 +188,12 @@ async function copyEmail(email: string, event: MouseEvent) {
         <h4 class="text-sm text-foreground mb-2">
           <span class="inline-flex items-center gap-1">
             Cross-list
-            <Tooltip.Root delayDuration={100}>
-              <Tooltip.Trigger>
-                <Info class="size-3 text-muted-foreground/50" />
-              </Tooltip.Trigger>
-              <Tooltip.Content
-                class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
-              >
-                Cross-listed sections share enrollment across multiple course numbers. Students in any linked section attend the same class.
-              </Tooltip.Content>
-            </Tooltip.Root>
+            <SimpleTooltip text="Cross-listed sections share enrollment across multiple course numbers. Students in any linked section attend the same class." delay={150} passthrough>
+              <Info class="size-3 text-muted-foreground/50" />
+            </SimpleTooltip>
           </span>
         </h4>
-        <Tooltip.Root delayDuration={100}>
+        <Tooltip.Root delayDuration={150} disableHoverableContent>
           <Tooltip.Trigger>
             <span class="inline-flex items-center gap-1.5 text-foreground font-mono">
               <span class="bg-card border border-border rounded-md px-2 py-0.5 text-xs font-medium">
@@ -233,7 +207,8 @@ async function copyEmail(email: string, event: MouseEvent) {
             </span>
           </Tooltip.Trigger>
           <Tooltip.Content
-            class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
+            sideOffset={6}
+            class="z-50 bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
           >
             Group <span class="font-mono font-medium">{course.crossList}</span>
             {#if course.crossListCount != null && course.crossListCapacity != null}
diff --git a/web/src/lib/components/CourseTable.svelte b/web/src/lib/components/CourseTable.svelte
index b748e8f..12d3bfa 100644
--- a/web/src/lib/components/CourseTable.svelte
+++ b/web/src/lib/components/CourseTable.svelte
@@ -24,7 +24,8 @@ import {
   type Updater,
 } from "@tanstack/table-core";
 import { ArrowUp, ArrowDown, ArrowUpDown, Columns3, Check, RotateCcw } from "@lucide/svelte";
-import { DropdownMenu, ContextMenu } from "bits-ui";
+import { DropdownMenu, ContextMenu, Tooltip } from "bits-ui";
+import SimpleTooltip from "./SimpleTooltip.svelte";
 import { fade, fly } from "svelte/transition";
 
 let {
@@ -33,12 +34,14 @@ let {
   sorting = [],
   onSortingChange,
   manualSorting = false,
+  subjectMap = {},
 }: {
   courses: CourseResponse[];
   loading: boolean;
   sorting?: SortingState;
   onSortingChange?: (sorting: SortingState) => void;
   manualSorting?: boolean;
+  subjectMap?: Record<string, string>;
 } = $props();
 
 let expandedCrn: string | null = $state(null);
@@ -301,12 +304,24 @@ const table = createSvelteTable({
 <!-- Toolbar: View columns button -->
 <div class="flex items-center justify-end pb-2">
   <DropdownMenu.Root>
-    <DropdownMenu.Trigger
-      class="inline-flex items-center gap-1.5 rounded-md border border-border bg-background px-2.5 py-1.5 text-xs font-medium text-muted-foreground hover:bg-accent hover:text-accent-foreground transition-colors cursor-pointer"
-    >
-      <Columns3 class="size-3.5" />
-      View
-    </DropdownMenu.Trigger>
+    <Tooltip.Root delayDuration={150} disableHoverableContent>
+      <Tooltip.Trigger>
+        <DropdownMenu.Trigger
+          class="inline-flex items-center gap-1.5 rounded-md border border-border bg-background px-2.5 py-1.5 text-xs font-medium text-muted-foreground hover:bg-accent hover:text-accent-foreground transition-colors cursor-pointer"
+        >
+          <Columns3 class="size-3.5" />
+          View
+        </DropdownMenu.Trigger>
+      </Tooltip.Trigger>
+      <Tooltip.Content
+        side="bottom"
+        sideOffset={6}
+        class="z-50 bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md"
+      >
+        Show or hide table columns
+      </Tooltip.Content>
+    </Tooltip.Root>
+
     <DropdownMenu.Portal>
       <DropdownMenu.Content
         class="z-50 min-w-[160px] rounded-md border border-border bg-card p-1 text-card-foreground shadow-lg"
@@ -399,20 +414,31 @@ const table = createSvelteTable({
                   {#if colId === "crn"}
                     <td class="py-2 px-2 font-mono text-xs text-muted-foreground/70">{course.crn}</td>
                   {:else if colId === "course_code"}
+                    {@const subjectDesc = subjectMap[course.subject]}
                     <td class="py-2 px-2 whitespace-nowrap">
-                      <span class="font-semibold">{course.subject} {course.courseNumber}</span>{#if course.sequenceNumber}<span class="text-muted-foreground">-{course.sequenceNumber}</span>{/if}
+                      <SimpleTooltip text={subjectDesc ? `${subjectDesc} ${course.courseNumber}` : `${course.subject} ${course.courseNumber}`} delay={200} side="bottom" passthrough>
+                        <span class="font-semibold">{course.subject} {course.courseNumber}</span>{#if course.sequenceNumber}<span class="text-muted-foreground">-{course.sequenceNumber}</span>{/if}
+                      </SimpleTooltip>
                     </td>
                   {:else if colId === "title"}
-                    <td class="py-2 px-2 font-medium max-w-[200px] truncate" title={course.title}>{course.title}</td>
+                    <td class="py-2 px-2 font-medium max-w-[200px] truncate">
+                      <SimpleTooltip text={course.title} delay={200} side="bottom" passthrough>
+                        <span class="block truncate">{course.title}</span>
+                      </SimpleTooltip>
+                    </td>
                   {:else if colId === "instructor"}
+                    {@const primary = getPrimaryInstructor(course.instructors)}
                     <td class="py-2 px-2 whitespace-nowrap">
-                      {primaryInstructorDisplay(course)}
+                      <SimpleTooltip text={primary?.displayName ?? "Staff"} delay={200} side="bottom" passthrough>
+                        <span>{primaryInstructorDisplay(course)}</span>
+                      </SimpleTooltip>
                       {#if primaryRating(course)}
                         {@const r = primaryRating(course)!}
-                        <span
-                          class="ml-1 text-xs font-medium {ratingColor(r.rating)}"
-                          title="{r.rating.toFixed(1)}/5 ({r.count} ratings)"
-                        >{r.rating.toFixed(1)}★</span>
+                        <SimpleTooltip text="{r.rating.toFixed(1)}/5 ({r.count} ratings on RateMyProfessors)" delay={150} side="bottom" passthrough>
+                          <span
+                            class="ml-1 text-xs font-medium {ratingColor(r.rating)}"
+                          >{r.rating.toFixed(1)}★</span>
+                        </SimpleTooltip>
                       {/if}
                     </td>
                   {:else if colId === "time"}
@@ -442,11 +468,13 @@ const table = createSvelteTable({
                     </td>
                   {:else if colId === "seats"}
                     <td class="py-2 px-2 text-right whitespace-nowrap">
-                      <span class="inline-flex items-center gap-1.5">
-                        <span class="size-1.5 rounded-full {seatsDotColor(course)} shrink-0"></span>
-                        <span class="{seatsColor(course)} font-medium tabular-nums">{#if openSeats(course) === 0}Full{:else}{openSeats(course)} open{/if}</span>
-                        <span class="text-muted-foreground/60 tabular-nums">{course.enrollment}/{course.maxEnrollment}{#if course.waitCount > 0} · WL {course.waitCount}/{course.waitCapacity}{/if}</span>
-                      </span>
+                      <SimpleTooltip text="{openSeats(course)} of {course.maxEnrollment} seats open, {course.enrollment} enrolled{course.waitCount > 0 ? `, ${course.waitCount} waitlisted` : ''}" delay={200} side="left" passthrough>
+                        <span class="inline-flex items-center gap-1.5">
+                          <span class="size-1.5 rounded-full {seatsDotColor(course)} shrink-0"></span>
+                          <span class="{seatsColor(course)} font-medium tabular-nums">{#if openSeats(course) === 0}Full{:else}{openSeats(course)} open{/if}</span>
+                          <span class="text-muted-foreground/60 tabular-nums">{course.enrollment}/{course.maxEnrollment}{#if course.waitCount > 0} · WL {course.waitCount}/{course.waitCapacity}{/if}</span>
+                        </span>
+                      </SimpleTooltip>
                     </td>
                   {/if}
                 {/each}
diff --git a/web/src/lib/components/SearchFilters.svelte b/web/src/lib/components/SearchFilters.svelte
index faf2039..3f121ef 100644
--- a/web/src/lib/components/SearchFilters.svelte
+++ b/web/src/lib/components/SearchFilters.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
 import type { Term, Subject } from "$lib/api";
+import SimpleTooltip from "./SimpleTooltip.svelte";
 
 let {
   terms,
@@ -45,8 +46,10 @@ let {
     class="border border-border bg-card text-foreground rounded-md px-3 py-1.5 text-sm flex-1 min-w-[200px]"
   />
 
-  <label class="flex items-center gap-1.5 text-sm text-muted-foreground cursor-pointer">
-    <input type="checkbox" bind:checked={openOnly} />
-    Open only
-  </label>
+  <SimpleTooltip text="Show only courses with available seats" delay={200} passthrough>
+    <label class="flex items-center gap-1.5 text-sm text-muted-foreground cursor-pointer">
+      <input type="checkbox" bind:checked={openOnly} />
+      Open only
+    </label>
+  </SimpleTooltip>
 </div>
diff --git a/web/src/lib/components/SimpleTooltip.svelte b/web/src/lib/components/SimpleTooltip.svelte
new file mode 100644
index 0000000..1359438
--- /dev/null
+++ b/web/src/lib/components/SimpleTooltip.svelte
@@ -0,0 +1,31 @@
+<script lang="ts">
+import { Tooltip } from "bits-ui";
+import type { Snippet } from "svelte";
+
+let {
+  text,
+  delay = 150,
+  side = "top",
+  passthrough = false,
+  children,
+}: {
+  text: string;
+  delay?: number;
+  side?: "top" | "bottom" | "left" | "right";
+  passthrough?: boolean;
+  children: Snippet;
+} = $props();
+</script>
+
+<Tooltip.Root delayDuration={delay} disableHoverableContent={passthrough}>
+  <Tooltip.Trigger>
+    {@render children()}
+  </Tooltip.Trigger>
+  <Tooltip.Content
+    {side}
+    sideOffset={6}
+    class="z-50 bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md max-w-72"
+  >
+    {text}
+  </Tooltip.Content>
+</Tooltip.Root>
diff --git a/web/src/lib/components/ThemeToggle.svelte b/web/src/lib/components/ThemeToggle.svelte
index 8cd7a60..2041472 100644
--- a/web/src/lib/components/ThemeToggle.svelte
+++ b/web/src/lib/components/ThemeToggle.svelte
@@ -2,6 +2,7 @@
 import { tick } from "svelte";
 import { Moon, Sun } from "@lucide/svelte";
 import { themeStore } from "$lib/stores/theme.svelte";
+import SimpleTooltip from "./SimpleTooltip.svelte";
 
 /**
  * Theme toggle with View Transitions API circular reveal animation.
@@ -42,25 +43,27 @@ async function handleToggle(event: MouseEvent) {
 }
 </script>
 
-<button
-  type="button"
-  onclick={(e) => handleToggle(e)}
-  aria-label={themeStore.isDark ? "Switch to light mode" : "Switch to dark mode"}
-  class="cursor-pointer border-none rounded-md flex items-center justify-center p-2 scale-125
-    text-muted-foreground hover:bg-muted bg-transparent transition-colors"
->
-  <div class="relative size-[18px]">
-    <Sun
-      size={18}
-      class="absolute inset-0 transition-all duration-300 {themeStore.isDark
-        ? 'rotate-90 scale-0 opacity-0'
-        : 'rotate-0 scale-100 opacity-100'}"
-    />
-    <Moon
-      size={18}
-      class="absolute inset-0 transition-all duration-300 {themeStore.isDark
-        ? 'rotate-0 scale-100 opacity-100'
-        : '-rotate-90 scale-0 opacity-0'}"
-    />
-  </div>
-</button>
+<SimpleTooltip text={themeStore.isDark ? "Switch to light mode" : "Switch to dark mode"} delay={200} side="bottom" passthrough>
+  <button
+    type="button"
+    onclick={(e) => handleToggle(e)}
+    aria-label={themeStore.isDark ? "Switch to light mode" : "Switch to dark mode"}
+    class="cursor-pointer border-none rounded-md flex items-center justify-center p-2 scale-125
+      text-muted-foreground hover:bg-muted bg-transparent transition-colors"
+  >
+    <div class="relative size-[18px]">
+      <Sun
+        size={18}
+        class="absolute inset-0 transition-all duration-300 {themeStore.isDark
+          ? 'rotate-90 scale-0 opacity-0'
+          : 'rotate-0 scale-100 opacity-100'}"
+      />
+      <Moon
+        size={18}
+        class="absolute inset-0 transition-all duration-300 {themeStore.isDark
+          ? 'rotate-0 scale-100 opacity-100'
+          : '-rotate-90 scale-0 opacity-0'}"
+      />
+    </div>
+  </button>
+</SimpleTooltip>
diff --git a/web/src/routes/+page.svelte b/web/src/routes/+page.svelte
index c298222..4910fac 100644
--- a/web/src/routes/+page.svelte
+++ b/web/src/routes/+page.svelte
@@ -51,6 +51,9 @@ function handleSortingChange(newSorting: SortingState) {
 
 // Data state
 let subjects: Subject[] = $state([]);
+let subjectMap: Record<string, string> = $derived(
+  Object.fromEntries(subjects.map((s) => [s.code, s.description]))
+);
 let searchResult: SearchResponse | null = $state(null);
 let loading = $state(false);
 let error = $state<string | null>(null);
@@ -181,6 +184,7 @@ function handlePageChange(newOffset: number) {
         {sorting}
         onSortingChange={handleSortingChange}
         manualSorting={true}
+        {subjectMap}
       />
 
       {#if searchResult}
diff --git a/web/src/routes/health/+page.svelte b/web/src/routes/health/+page.svelte
index 8e7dd2a..98acf69 100644
--- a/web/src/routes/health/+page.svelte
+++ b/web/src/routes/health/+page.svelte
@@ -12,7 +12,7 @@ import {
   WifiOff,
   XCircle,
 } from "@lucide/svelte";
-import { Tooltip } from "bits-ui";
+import SimpleTooltip from "$lib/components/SimpleTooltip.svelte";
 import { type ServiceStatus, type ServiceInfo, type StatusResponse, client } from "$lib/api";
 import { relativeTime } from "$lib/time";
 
@@ -290,20 +290,13 @@ onMount(() => {
               <Clock size={13} />
               <span class="text-sm text-muted-foreground">Last Updated</span>
             </div>
-            <Tooltip.Root>
-              <Tooltip.Trigger>
-                <abbr
-                  class="cursor-pointer underline decoration-dotted decoration-border underline-offset-[6px]"
-                >
-                  <span class="text-sm text-muted-foreground">{relativeLastFetch}</span>
-                </abbr>
-              </Tooltip.Trigger>
-              <Tooltip.Content
-                class="bg-card text-card-foreground text-xs border border-border rounded-md px-2.5 py-1.5 shadow-md"
+            <SimpleTooltip text="as of {lastFetch.toLocaleTimeString()}" delay={150} passthrough>
+              <abbr
+                class="cursor-pointer underline decoration-dotted decoration-border underline-offset-[6px]"
               >
-                as of {lastFetch.toLocaleTimeString()}
-              </Tooltip.Content>
-            </Tooltip.Root>
+                <span class="text-sm text-muted-foreground">{relativeLastFetch}</span>
+              </abbr>
+            </SimpleTooltip>
           </div>
         {/if}
       </div>
diff --git a/web/src/routes/layout.css b/web/src/routes/layout.css
index d7eda81..c1b45e6 100644
--- a/web/src/routes/layout.css
+++ b/web/src/routes/layout.css
@@ -12,6 +12,8 @@
   --muted-foreground: oklch(0.556 0 0);
   --border: oklch(0.922 0 0);
   --ring: oklch(0.708 0 0);
+  --accent: oklch(0.96 0 0);
+  --accent-foreground: oklch(0.145 0 0);
 
   --status-green: oklch(0.65 0.2 145);
   --status-red: oklch(0.63 0.2 25);
@@ -28,6 +30,8 @@
   --muted-foreground: oklch(0.708 0 0);
   --border: oklch(0.269 0 0);
   --ring: oklch(0.556 0 0);
+  --accent: oklch(0.269 0 0);
+  --accent-foreground: oklch(0.985 0 0);
 
   --status-green: oklch(0.72 0.19 145);
   --status-red: oklch(0.7 0.19 25);
@@ -44,6 +48,8 @@
   --color-muted-foreground: var(--muted-foreground);
   --color-border: var(--border);
   --color-ring: var(--ring);
+  --color-accent: var(--accent);
+  --color-accent-foreground: var(--accent-foreground);
   --color-status-green: var(--status-green);
   --color-status-red: var(--status-red);
   --color-status-orange: var(--status-orange);