diff --git a/src/iframe/life-game.js b/src/iframe/life-game.js
index 48f5517..ba97e7d 100644
--- a/src/iframe/life-game.js
+++ b/src/iframe/life-game.js
@@ -281,7 +281,6 @@ on.save_board = async () => {
 };
 
 on.apply_board = (newBoard) => {
-  boardSize = newBoard.length;
   board = newBoard;
   renderBoard();
   generationChange(0);
diff --git a/src/lib/api/board.ts b/src/lib/api/board.ts
index 9d62781..bf474eb 100644
--- a/src/lib/api/board.ts
+++ b/src/lib/api/board.ts
@@ -1,3 +1,5 @@
+import { toast } from "$lib/models/ToastStore.svelte";
+
 export async function saveBoard(data: { board: number[][]; name: string }, isJapanese: boolean) {
   try {
     const response = await fetch("/api/board", {
@@ -13,16 +15,16 @@ export async function saveBoard(data: { board: number[][]; name: string }, isJap
     }
 
     if (isJapanese) {
-      alert("盤面を保存しました！");
+      toast.show("盤面を保存しました！", "success");
     } else {
-      alert("Board saved!");
+      toast.show("Board saved!", "success");
     }
   } catch (err) {
     console.error("Save Error:", err);
     if (isJapanese) {
-      alert("保存に失敗しました。");
+      toast.show("保存に失敗しました。", "error");
     } else {
-      alert("Failed to save.");
+      toast.show("Failed to save.", "error");
     }
   }
 }
@@ -52,9 +54,9 @@ export async function fetchBoardList(isJapanese: boolean): Promise<BoardListItem
   } catch (err) {
     console.error("Load error", err);
     if (isJapanese) {
-      alert("読み込みに失敗しました。");
+      toast.show("読み込みに失敗しました。", "error");
     } else {
-      alert("Failed to load.");
+      toast.show("Failed to load.", "error");
     }
   }
 }
@@ -80,9 +82,9 @@ export async function loadBoardById(
   } catch (err) {
     console.error("Load error", err);
     if (isJapanese) {
-      alert("読み込みに失敗しました。");
+      toast.show("読み込みに失敗しました。", "error");
     } else {
-      alert("Failed to load.");
+      toast.show("Failed to load.", "error");
     }
   }
 }
diff --git a/src/lib/api/code.ts b/src/lib/api/code.ts
index d40f414..efbb3dc 100644
--- a/src/lib/api/code.ts
+++ b/src/lib/api/code.ts
@@ -1,3 +1,5 @@
+import { toast } from "$lib/models/ToastStore.svelte";
+
 export async function saveCode(data: { code: string; name: string }, isJapanese: boolean) {
   try {
     const response = await fetch("/api/code", {
@@ -13,16 +15,16 @@ export async function saveCode(data: { code: string; name: string }, isJapanese:
     }
 
     if (isJapanese) {
-      alert("コードを保存しました！");
+      toast.show("コードを保存しました！", "success");
     } else {
-      alert("Code saved!");
+      toast.show("Code saved!", "success");
     }
   } catch (err) {
     console.error("Save Error:", err);
     if (isJapanese) {
-      alert("保存に失敗しました。");
+      toast.show("保存に失敗しました。", "error");
     } else {
-      alert("Failed to save.");
+      toast.show("Failed to save.", "error");
     }
   }
 }
@@ -51,9 +53,9 @@ export async function fetchCodeList(isJapanese: boolean): Promise<CodeListItem[]
   } catch (err) {
     console.error("Load error", err);
     if (isJapanese) {
-      alert("読み込みに失敗しました。");
+      toast.show("読み込みに失敗しました。", "error");
     } else {
-      alert("Failed to load.");
+      toast.show("Failed to load.", "error");
     }
   }
 }
@@ -76,9 +78,9 @@ export async function loadCodeById(id: number, isJapanese: boolean): Promise<str
   } catch (err) {
     console.error("Load error", err);
     if (isJapanese) {
-      alert("読み込みに失敗しました。");
+      toast.show("読み込みに失敗しました。", "error");
     } else {
-      alert("Failed to load.");
+      toast.show("Failed to load.", "error");
     }
   }
 }
diff --git a/src/lib/components/BoardModals.svelte b/src/lib/components/BoardModals.svelte
index d674bed..17841a8 100644
--- a/src/lib/components/BoardModals.svelte
+++ b/src/lib/components/BoardModals.svelte
@@ -51,7 +51,7 @@
         >
         <button
           type="submit"
-          class="btn btn-primary"
+          class="btn btn-success text-black"
           onclick={() => manager.save(isJapanese)}
           disabled={!manager.saveState.saving}
         >
@@ -103,7 +103,10 @@
                 <td>{item.name}</td>
                 <td>{new Date(item.createdAt).toLocaleString(isJapanese ? "ja-JP" : "en-US")}</td>
                 <td class="text-right">
-                  <button class="btn btn-sm btn-primary" onclick={() => onSelect(item.id)}>
+                  <button
+                    class="btn btn-sm btn-success text-black"
+                    onclick={() => onSelect(item.id)}
+                  >
                     {isJapanese ? "ロード" : "Load"}
                   </button>
                 </td>
diff --git a/src/lib/components/CodeModals.svelte b/src/lib/components/CodeModals.svelte
index a1efac5..a7ee468 100644
--- a/src/lib/components/CodeModals.svelte
+++ b/src/lib/components/CodeModals.svelte
@@ -37,7 +37,7 @@
         >
         <button
           type="submit"
-          class="btn btn-primary"
+          class="btn btn-success text-black"
           onclick={() => manager.save(isJapanese)}
           disabled={!manager.saveState.saving}
         >
@@ -77,7 +77,10 @@
                 <td>{item.name}</td>
                 <td>{new Date(item.createdAt).toLocaleString(isJapanese ? "ja-JP" : "en-US")}</td>
                 <td class="text-right">
-                  <button class="btn btn-sm btn-primary" onclick={() => onSelect(item.id)}>
+                  <button
+                    class="btn btn-sm btn-success text-black"
+                    onclick={() => onSelect(item.id)}
+                  >
                     {isJapanese ? "ロード" : "Load"}
                   </button>
                 </td>
diff --git a/src/lib/components/GlobalToast.svelte b/src/lib/components/GlobalToast.svelte
new file mode 100644
index 0000000..e25e48f
--- /dev/null
+++ b/src/lib/components/GlobalToast.svelte
@@ -0,0 +1,24 @@
+<script lang="ts">
+  import { toast } from "$lib/models/ToastStore.svelte";
+
+  let alertClass: string = $derived.by(() => {
+    switch (toast.type) {
+      case "success":
+        return "alert-success";
+      case "error":
+        return "alert-error";
+      default:
+        return "alert-info";
+    }
+  });
+</script>
+
+{#if toast.visible}
+  <div class="toast toast-middle toast-center">
+    <div class={`alert ${alertClass} p-3 text-lg`}>
+      <div>
+        <span>{toast.message}</span>
+      </div>
+    </div>
+  </div>
+{/if}
diff --git a/src/lib/models/ToastStore.svelte.ts b/src/lib/models/ToastStore.svelte.ts
new file mode 100644
index 0000000..e6e141e
--- /dev/null
+++ b/src/lib/models/ToastStore.svelte.ts
@@ -0,0 +1,38 @@
+export class ToastStore {
+  message = $state("");
+  type = $state<"success" | "error" | "info">("info");
+  visible = $state(false);
+
+  private timerId: ReturnType<typeof setTimeout> | undefined = $state(undefined);
+
+  /**
+   * トーストを表示する
+   * @param message 表示するメッセージ
+   * @param type "success" | "error" | "info"
+   * @param duration 表示時間（ミリ秒）
+   */
+  show(message: string, type: "success" | "error" | "info" = "info", duration: number = 2000) {
+    this.message = message;
+    this.type = type;
+    this.visible = true;
+
+    if (this.timerId) {
+      clearTimeout(this.timerId);
+    }
+
+    this.timerId = setTimeout(() => {
+      this.hide();
+    }, duration);
+  }
+
+  hide() {
+    this.visible = false;
+    if (this.timerId) {
+      clearTimeout(this.timerId);
+      this.timerId = undefined;
+    }
+  }
+}
+
+// グローバルで使うための単一インスタンスを作成してエクスポート
+export const toast = new ToastStore();
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index d8d8756..9600347 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -1,6 +1,7 @@
 <script lang="ts">
   import favicon from "$lib/assets/favicon.svg";
   import "../app.css";
+  import GlobalToast from "$lib/components/GlobalToast.svelte";
   let { children } = $props();
 </script>
 
@@ -8,4 +9,4 @@
   <link rel="icon" href={favicon} />
 </svelte:head>
 
-{@render children?.()}
+<GlobalToast />{@render children?.()}
diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index a3724e7..00ffdd9 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -9,6 +9,7 @@
   import { CodeManager } from "$lib/models/CodeManager.svelte";
   import BoardModals from "$lib/components/BoardModals.svelte";
   import CodeModals from "$lib/components/CodeModals.svelte";
+  import { toast } from "$lib/models/ToastStore.svelte";
   import CodeMirror from "svelte-codemirror-editor";
   import { javascript } from "@codemirror/lang-javascript";
   import { oneDark } from "@codemirror/theme-one-dark";
@@ -32,6 +33,16 @@
   const boardManager = new BoardManager();
   const codeManager = new CodeManager();
 
+  let disabledTemplates: { [key: string]: boolean } = $derived.by(() => {
+    const newDisabledState: { [key: string]: boolean } = {};
+    for (const key in patterns) {
+      const patternName = key as keyof typeof patterns;
+      const patternData = patterns[patternName];
+      newDisabledState[patternName] = sizeValue < (patternData.minBoardSize || 0);
+    }
+    return newDisabledState;
+  });
+
   let timer: "running" | "stopped" = $state("stopped");
   let intervalMs = $state(1000);
   $effect(() => {
@@ -45,7 +56,6 @@
   type OngoingEvent =
     | "play"
     | "pause"
-    | "state_update"
     | "board_reset"
     | "board_randomize"
     | "place_template"
@@ -69,10 +79,11 @@
         break;
       }
       case "Size shortage": {
-        alert(
+        toast.show(
           isJapanese
             ? "盤面からはみ出してしまうため、キャンセルしました"
             : "This action was canceled because it would have extended beyond the board.",
+          "error",
         );
         break;
       }
@@ -101,7 +112,6 @@
   async function onBoardSelect(id: number) {
     const board = await boardManager.load(id, isJapanese);
     if (board) {
-      sizeValue = board.length;
       sendEvent("apply_board", board);
     }
   }
@@ -169,31 +179,27 @@
   <div class="bg-base-200 shadow-lg p-4 h-48 w-full overflow-x-auto">
     <div class="flex gap-4">
       {#each Object.keys(patterns) as (keyof typeof patterns)[] as patternName (patternName)}
-        <div class="text-center flex-shrink-0">
+        <div
+          class="text-center flex-shrink-0"
+          style:opacity={disabledTemplates[patternName] ? 0.3 : 1}
+        >
           <p class="font-bold mb-2">
             {isJapanese ? patterns[patternName].names.ja : patterns[patternName].names.en}
           </p>
           <button
             class="btn overflow-hidden p-0 w-24 h-24"
             onclick={() => {
-              sendEvent("request_sync");
-
-              const patternData = patterns[patternName];
-              const patternShape = patternData.shape;
-
-              if (sizeValue < (patternData.minBoardSize || 0)) {
-                if (isJapanese) {
-                  alert(
-                    `このパターンには ${patternData.minBoardSize}x${patternData.minBoardSize} 以上の盤面が必要です`,
-                  );
-                } else {
-                  alert(
-                    `This pattern requires a board size of at least ${patternData.minBoardSize}x${patternData.minBoardSize}.`,
-                  );
-                }
-
+              if (disabledTemplates[patternName]) {
+                toast.show(
+                  isJapanese
+                    ? `このパターンには ${patterns[patternName].minBoardSize}x${patterns[patternName].minBoardSize} 以上の盤面が必要です`
+                    : `This pattern requires a board size of at least ${patterns[patternName].minBoardSize}x${patterns[patternName].minBoardSize}.`,
+                  "error",
+                );
                 return;
               }
+              const patternData = patterns[patternName];
+              const patternShape = patternData.shape;
               bottomDrawerOpen = false;
               sendEvent("place_template", patternShape);
             }}
@@ -253,7 +259,7 @@
       class="w-[80%] h-[90%] rounded-lg mx-auto my-5 bg-white shadow-lg"
       onload={() => {
         setTimeout(() => {
-          sendEvent("state_update");
+          sendEvent("request_sync");
           console.log("generationFigure onload:", generationFigure);
         }, 50);
       }}
@@ -283,7 +289,7 @@
   <!-- Left Section -->
   <div class="flex items-center">
     <button
-      class="btn rounded-none h-12 justify-start"
+      class="btn rounded-none h-12 justify-start w-30"
       onclick={() => (bottomDrawerOpen = !bottomDrawerOpen)}
     >
       {#if bottomDrawerOpen}
@@ -295,8 +301,8 @@
       {/if}
     </button>
 
-    <div class="font-bold text-black ml-4">
-      {isJapanese ? "第" + generationFigure + "世代" : "Generation:" + generationFigure}
+    <div class="font-bold text-black ml-4 w-25">
+      {isJapanese ? "世代数:" + generationFigure : "Generation:" + generationFigure}
     </div>
   </div>
 
@@ -329,17 +335,13 @@
       <img class="size-6" src={icons.accelerate} alt="accelerate" />
     </button>
 
-    <div class="font-bold text-black ml-2">
+    <div class="font-bold text-black ml-2 w-25">
       {isJapanese ? "現在の速度" : "Current speed"}: x{1000 / intervalMs}
     </div>
 
     <div class="w-px bg-gray-400 h-6 mx-4"></div>
     <!-- Separator -->
 
-    <button class="btn btn-ghost btn-circle hover:bg-[rgb(220,220,220)]">
-      <img class="size-6" src={icons.LeftArrow} alt="Left Arrow" />
-    </button>
-
     <button
       class="btn btn-ghost btn-circle hover:bg-[rgb(220,220,220)] swap"
       onclick={() => {
@@ -357,10 +359,6 @@
       <img class="size-6 swap-on" src={icons.Pause} alt="Pause" />
       <img class="size-6 swap-off" src={icons.Play} alt="Play" />
     </button>
-
-    <button class="btn btn-ghost btn-circle hover:bg-[rgb(220,220,220)]">
-      <img class="size-6" src={icons.RightArrow} alt="Right Arrow" />
-    </button>
   </div>
 
   <!-- Right Section -->
@@ -418,7 +416,10 @@
     <!-- Separator -->
     <div class="font-bold text-black">{isJapanese ? "コード" : "Code"}:</div>
     <button
-      class="btn btn-ghost hover:bg-[rgb(220,220,220)] text-black"
+      class={[
+        "btn text-black",
+        editingCode === appliedCode ? "btn-ghost hover:bg-[rgb(220,220,220)]" : "btn-success",
+      ]}
       onclick={() => {
         appliedCode = editingCode;
         isProgress = false;