diff --git a/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte b/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte
index 6b286cd96..e67399597 100644
--- a/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte
+++ b/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte
@@ -20,7 +20,7 @@
 // Component
 <button
   type="button"
-  onclick={() => updatingDropdown.toggle()} // Open / close the dropdown.
+  onclick={(event) => updatingDropdown.toggle(event)} // Open / close the dropdown.
 >
 
 <UpdatingDropdown bind:this={updatingDropdown} {taskResult} {isLoggedIn} {onupdate} />
@@ -30,6 +30,7 @@
   import { enhance } from '$app/forms';
 
   import { Dropdown, DropdownUl, DropdownLi, uiHelpers } from 'svelte-5-ui-lib';
+  import Check from 'lucide-svelte/icons/check';
 
   import type { TaskResult } from '$lib/types/task';
 
@@ -55,15 +56,49 @@
   let dropdownStatus = $state(false);
   let closeDropdown = dropdown.close;
 
+  let dropdownX = $state(0);
+  let dropdownY = $state(0);
+  let isLowerHalfInScreen = $state(false);
+
   $effect(() => {
     activeUrl = $page.url.pathname;
     dropdownStatus = dropdown.isOpen;
+
+    if (dropdownStatus) {
+      document.documentElement.style.setProperty('--dropdown-x', `${dropdownX}px`);
+      document.documentElement.style.setProperty('--dropdown-y', `${dropdownY}px`);
+    }
   });
 
-  export function toggle(): void {
+  export function toggle(event?: MouseEvent): void {
+    if (event) {
+      getDropdownPosition(event);
+    }
+
     dropdown.toggle();
   }
 
+  function getDropdownPosition(event: MouseEvent): void {
+    const rect = (event.currentTarget as HTMLElement).getBoundingClientRect();
+
+    dropdownX = rect.right;
+    dropdownY = rect.bottom;
+
+    isLowerHalfInScreen = rect.top > window.innerHeight / 2;
+  }
+
+  function getDropdownClasses(isLower: boolean): string {
+    let classes =
+      'absolute w-32 z-[999] shadow-lg pointer-events-auto left-[var(--dropdown-x)] transform -translate-x-full ';
+
+    if (isLower) {
+      classes += 'bottom-[calc(100vh-var(--dropdown-y))] mb-5';
+    } else {
+      classes += 'top-[var(--dropdown-y)] mt-1';
+    }
+    return classes;
+  }
+
   let selectedSubmissionStatus = $state<SubmissionStatus>();
   let showForm = $state(false);
 
@@ -175,19 +210,17 @@
   });
 </script>
 
-<div class="relative">
+<div class="fixed inset-0 pointer-events-none z-50 w-full h-full">
   <Dropdown
     {activeUrl}
     {dropdownStatus}
     {closeDropdown}
-    class="absolute w-32 z-20 left-auto right-0 mt-8"
+    class={getDropdownClasses(isLowerHalfInScreen)}
   >
-    <DropdownUl>
+    <DropdownUl class="border rounded-lg shadow">
       {#if isLoggedIn}
         {#each submissionStatusOptions as submissionStatus}
-          <DropdownLi href="javascript:void(0)" onclick={() => handleClick(submissionStatus)}>
-            {submissionStatus.labelName}
-          </DropdownLi>
+          {@render dropdownListForSubmissionStatus(taskResult, submissionStatus)}
         {/each}
       {:else}
         <DropdownLi href={SIGNUP_PAGE}>アカウント作成</DropdownLi>
@@ -201,6 +234,21 @@
   {/if}
 </div>
 
+{#snippet dropdownListForSubmissionStatus(
+  taskResult: TaskResult,
+  submissionStatus: SubmissionStatus,
+)}
+  <DropdownLi href="javascript:void(0)" onclick={() => handleClick(submissionStatus)}>
+    <div class="flex items-center justify-between">
+      {submissionStatus.labelName}
+
+      {#if taskResult.status_name === submissionStatus.innerName}
+        <Check class="w-4 h-4 text-primary-600 dark:text-gray-300" strokeWidth={3} />
+      {/if}
+    </div>
+  </DropdownLi>
+{/snippet}
+
 {#snippet submissionStatusForm(selectedTaskResult: TaskResult, submissionStatus: SubmissionStatus)}
   <form
     id="submissionStatusForm"
diff --git a/src/lib/components/TaskTables/TaskTable.svelte b/src/lib/components/TaskTables/TaskTable.svelte
index 7950c9015..f443942be 100644
--- a/src/lib/components/TaskTables/TaskTable.svelte
+++ b/src/lib/components/TaskTables/TaskTable.svelte
@@ -54,7 +54,7 @@
   }
 
   function getBodyCellClasses(contestId: string, taskIndex: string): string {
-    const baseClasses = 'w-1/2 xs:w-1/3 sm:w-1/4 md:w-1/5 lg:w-1/6 px-1 py-1 border';
+    const baseClasses = 'w-1/2 xs:w-1/3 sm:w-1/4 md:w-1/5 lg:w-1/6 px-1 py-1';
     const backgroundColor = getBackgroundColor(taskTable[contestId][taskIndex]);
 
     return `${baseClasses} ${backgroundColor}`;
@@ -129,34 +129,34 @@
 </Heading>
 
 <!-- TODO: ページネーションを実装 -->
-<!-- TODO: ヘッダーを固定できるようにする。-->
-<!-- HACK: Flowbite と tailwindcss の相性が悪いのかもしれない。tailwindcss のクラス指定、raw HTML & CSS を試したが、いずれも実現できず。 -->
 <!-- See: -->
 <!-- https://github.com/kenkoooo/AtCoderProblems/blob/master/atcoder-problems-frontend/src/pages/TablePage/AtCoderRegularTable.tsx -->
 <!-- https://github.com/birdou/atcoder-blogs/blob/main/app/atcoder-blogs-frontend/src/pages/BlogTablePage/BlogTablePage.tsx -->
 <!-- https://tailwindcss.com/docs/position#sticky-positioning-elements -->
-<div class="container w-full overflow-hidden rounded-md border border-gray-100 shadow-sm">
-  <div class="w-full overflow-auto">
+<div class="container w-full rounded-md border shadow-sm">
+  <div class="w-full sticky top-0 z-20 border-b">
     <Table id="task-table" class="text-md table-fixed w-full" aria-label="Task table">
       <TableHead class="text-sm bg-gray-100">
-        <TableHeadCell class="w-full xl:w-16 px-2 text-center border" scope="col">
-          Round
-        </TableHeadCell>
+        <TableHeadCell class="w-full xl:w-16 px-2 text-center" scope="col">Round</TableHeadCell>
 
         {#if taskTableHeaderIds.length}
           {#each taskTableHeaderIds as taskTableHeaderId}
-            <TableHeadCell class="text-center border" scope="col">
+            <TableHeadCell class="text-center" scope="col">
               {taskTableHeaderId}
             </TableHeadCell>
           {/each}
         {/if}
       </TableHead>
+    </Table>
+  </div>
 
+  <div class="w-full overflow-auto max-h-[calc(80vh-56px)]">
+    <Table id="task-table" class="text-md table-fixed w-full" aria-label="Task table">
       <TableBody class="divide-y">
         {#if contestIds.length && taskTableHeaderIds.length}
           {#each contestIds as contestId}
             <TableBodyRow class="flex flex-wrap xl:table-row">
-              <TableBodyCell class="w-full xl:w-16 truncate px-2 py-2 text-center border">
+              <TableBodyCell class="w-full xl:w-16 truncate px-2 py-2 text-center">
                 {getContestRoundLabel(provider, contestId)}
               </TableBodyCell>
 
diff --git a/src/lib/components/TaskTables/TaskTableBodyCell.svelte b/src/lib/components/TaskTables/TaskTableBodyCell.svelte
index 5ae8e1e4b..9ef115c84 100644
--- a/src/lib/components/TaskTables/TaskTableBodyCell.svelte
+++ b/src/lib/components/TaskTables/TaskTableBodyCell.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import EllipsisVertical from 'lucide-svelte/icons/ellipsis-vertical';
+  import ChevronDown from 'lucide-svelte/icons/chevron-down';
 
   import type { TaskResult } from '$lib/types/task';
 
@@ -20,10 +20,12 @@
   let updatingDropdown: UpdatingDropdown;
 </script>
 
-<div class="flex items-center w-full space-x-1 text-left text-sm sm:text-md">
+<div
+  class="flex items-center w-full pl-0 lg:pl-1 space-x-1 lg:space-x-2 text-left text-sm sm:text-md"
+>
   {@render taskGradeLabel(taskResult)}
 
-  <div class="flex justify-between w-full min-w-0">
+  <div class="flex items-center justify-between w-full min-w-0">
     {@render taskTitleAndExternalLink(taskResult)}
     {@render submissionUpdaterAndLinksOfTaskDetailPage(taskResult)}
   </div>
@@ -59,10 +61,10 @@
     <button
       type="button"
       class="flex-shrink-0 w-6 ml-auto"
-      onclick={() => updatingDropdown.toggle()}
+      onclick={(event) => updatingDropdown.toggle(event)}
       aria-label="Update submission for {selectedTaskResult.title}"
     >
-      <EllipsisVertical class="w-4 h-4 mx-auto" />
+      <ChevronDown class="w-4 h-4 mx-auto" />
     </button>
 
     <UpdatingDropdown bind:this={updatingDropdown} {taskResult} {isLoggedIn} {onupdate} />