diff --git a/src/app/globals.css b/src/app/globals.css
index d96e7b4..0bbabcb 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -93,10 +93,15 @@
   --border: #BDE3EC;
   --input: #FFFFFF;
   --ring: #5BBECE;
+  --chart-1: #c2622d;
   --chart-1: oklch(0.646 0.222 41.116);
+  --chart-2: #3a9e94;
   --chart-2: oklch(0.6 0.118 184.704);
+  --chart-3: #2e5e8e;
   --chart-3: oklch(0.398 0.07 227.392);
+  --chart-4: #d4b84a;
   --chart-4: oklch(0.828 0.189 84.429);
+  --chart-5: #c8a030;
   --chart-5: oklch(0.769 0.188 70.08);
   --sidebar: #EEF7F9;
   --sidebar-foreground: #1A4A5A;
@@ -111,6 +116,30 @@
   --dark-body: #1A4A5A;
   --dark-description: #3A8A9A;
   --dark-border: #BDE3EC;
+
+  /* 유체 타이포그래피: clamp(최솟값, 뷰포트 기반 선호값, 최댓값) */
+  --fs-xs:   clamp(0.6875rem, 0.0625vw + 0.675rem,  0.75rem);
+  --fs-sm:   clamp(0.8125rem, 0.0625vw + 0.8rem,    0.875rem);
+  --fs-base: clamp(0.875rem,  0.125vw  + 0.85rem,   1rem);
+  --fs-lg:   clamp(1rem,      0.125vw  + 0.975rem,  1.125rem);
+  --fs-xl:   clamp(1.125rem,  0.125vw  + 1.1rem,    1.25rem);
+  --fs-2xl:  clamp(1.25rem,   0.25vw   + 1.2rem,    1.5rem);
+
+  /* 유체 간격: 동일 공식으로 저해상도↔고해상도 자연스럽게 전환 */
+  --sp-2:  clamp(0.375rem, 0.125vw + 0.35rem,  0.5rem);
+  --sp-3:  clamp(0.625rem, 0.125vw + 0.6rem,   0.75rem);
+  --sp-4:  clamp(0.875rem, 0.125vw + 0.85rem,  1rem);
+  --sp-6:  clamp(1.25rem,  0.25vw  + 1.2rem,   1.5rem);
+  --sp-8:  clamp(1.5rem,   0.5vw   + 1.4rem,   2rem);
+
+  /* 컴포넌트별 유체 값 */
+  --fluid-gap-kanban:  clamp(0.75rem, 0.75vw  + 0.6rem,   1.5rem);
+  --fluid-px-outer:    clamp(0.5rem,  1.25vw,              1rem);
+  --fluid-py-outer:    clamp(0.5rem,  0.625vw + 0.25rem,  0.75rem);
+  --fluid-modal-py:    clamp(1.5rem,  1.25vw  + 1.25rem,  2.25rem);
+  --fluid-modal-px:    clamp(1.25rem, 0.85vw  + 1.05rem,  1.75rem);
+  --fluid-modal-min-h: clamp(12rem,   40vh,                17rem);
+  --fluid-textarea-p:  clamp(0.75rem, 0.4vw   + 0.675rem, 1rem);
 }
 
 .dark {
@@ -133,10 +162,15 @@
   --border: #2A6070;
   --input: #1A4A5A;
   --ring: #6DD5E8;
+  --chart-1: #3a6fd8;
   --chart-1: oklch(0.488 0.243 264.376);
+  --chart-2: #4db89a;
   --chart-2: oklch(0.696 0.17 162.48);
+  --chart-3: #c8a030;
   --chart-3: oklch(0.769 0.188 70.08);
+  --chart-4: #9b4fd8;
   --chart-4: oklch(0.627 0.265 303.9);
+  --chart-5: #d84a3a;
   --chart-5: oklch(0.645 0.246 16.439);
   --sidebar: #0D2530;
   --sidebar-foreground: #E8F5F7;
@@ -154,6 +188,14 @@
 }
 
 @layer base {
+  html {
+    /* Windows 고정 스크롤바(15-17px)로 인한 레이아웃 밀림 방지 */
+    scrollbar-gutter: stable;
+  }
+  *, *::before, *::after {
+    /* OS별 box model 차이 통일 */
+    box-sizing: border-box;
+  }
   * {
     @apply border-border outline-ring/50;
   }
@@ -162,6 +204,11 @@
   }
 }
 
+/* 스크롤바 공간 예약 — Mac/Windows 레이아웃 일치 */
+.scrollbar-gutter-stable {
+  scrollbar-gutter: stable;
+}
+
 /* ==========================================================================
    React Calendar (react-calendar)
    ========================================================================== */
@@ -633,7 +680,6 @@
   overflow-y: auto;
   overflow-x: hidden;
   overscroll-behavior: contain;
-  -webkit-overflow-scrolling: touch;
   scrollbar-width: thin;
   scrollbar-color: var(--color-gray-300) transparent;
 }
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index d89a363..e8627fe 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -38,7 +38,7 @@ export default function RootLayout({
           <AuthProviders>
             <div className="h-full flex flex-col">
               <Header />
-              <div className="flex-1 overflow-auto">{children}</div>
+              <div className="flex-1 min-w-0 overflow-auto scrollbar-gutter-stable">{children}</div>
               <Toaster />
             </div>
           </AuthProviders>
diff --git a/src/components/features/kanban/KanbanBoard.tsx b/src/components/features/kanban/KanbanBoard.tsx
index fd272a2..f38260f 100644
--- a/src/components/features/kanban/KanbanBoard.tsx
+++ b/src/components/features/kanban/KanbanBoard.tsx
@@ -454,10 +454,10 @@ function ColumnGrid({
   isDragging: boolean;
 }) {
   return (
-    <div className="flex-1 min-h-0 flex flex-col px-2 sm:px-4 py-2 sm:py-3">
+    <div className="flex-1 min-h-0 flex flex-col px-(--fluid-px-outer) py-(--fluid-py-outer)">
       <div className="h-full flex flex-col rounded-lg border border-border overflow-hidden bg-[#F0F4F5] dark:bg-muted/20">
-        <div className="flex-1 min-h-0 overflow-x-auto overflow-y-auto">
-          <div className="flex gap-4 h-full justify-start sm:justify-center min-w-fit p-4">
+        <div className="flex-1 min-h-0 overflow-x-auto overflow-y-auto scrollbar-gutter-stable">
+          <div className="flex gap-(--fluid-gap-kanban) h-full justify-start sm:justify-center min-w-fit p-(--fluid-gap-kanban) 2xl:max-w-[1680px] 2xl:mx-auto">
             {KANBAN_COLUMNS.map((column) => (
               <KanbanColumn
                 key={column.id}
diff --git a/src/components/features/kanban/MemoView.tsx b/src/components/features/kanban/MemoView.tsx
index f2a76f0..ff9c68f 100644
--- a/src/components/features/kanban/MemoView.tsx
+++ b/src/components/features/kanban/MemoView.tsx
@@ -612,7 +612,7 @@ const MemoView = ({ projectId }: MemoFormProps) => {
             placeholder="메모를 입력하세요..."
             disabled={loadingMemos}
             rows={3}
-            className="w-full p-3 sm:p-4 pr-8 sm:pr-10 border border-gray-200 dark:border-gray-700 bg-white dark:bg-gray-900/50 rounded-xl resize-none text-sm input-focus-style transition-all placeholder:text-gray-400 dark:placeholder:text-gray-500 text-gray-900 dark:text-gray-100 disabled:opacity-50"
+            className="w-full pt-(--fluid-textarea-p) pb-(--fluid-textarea-p) pl-(--fluid-textarea-p) pr-8 sm:pr-10 border border-gray-200 dark:border-gray-700 bg-white dark:bg-gray-900/50 rounded-xl resize-none text-sm input-focus-style transition-all placeholder:text-gray-400 dark:placeholder:text-gray-500 text-gray-900 dark:text-gray-100 disabled:opacity-50"
           />
           {newMemo && (
             <button
@@ -801,7 +801,7 @@ const MemoView = ({ projectId }: MemoFormProps) => {
 
                 {/* 작성자 */}
                 <div className="flex justify-end">
-                  <span className="inline-flex items-center gap-1.5 px-2 py-1 bg-white/60 dark:bg-gray-800/60 backdrop-blur-sm rounded-md text-xs text-gray-600 dark:text-gray-400">
+                  <span className="inline-flex items-center gap-1.5 px-2 py-1 bg-white/80 dark:bg-gray-800/80 supports-backdrop-filter:bg-white/60 supports-backdrop-filter:dark:bg-gray-800/60 supports-backdrop-filter:backdrop-blur-sm rounded-md text-xs text-gray-600 dark:text-gray-400">
                     <svg
                       className="w-3 h-3"
                       fill="currentColor"
diff --git a/src/components/ui/Modal.tsx b/src/components/ui/Modal.tsx
index b402ac4..0e7d2f0 100644
--- a/src/components/ui/Modal.tsx
+++ b/src/components/ui/Modal.tsx
@@ -4,17 +4,13 @@ import clsx from "clsx";
 import Button from "@/components/ui/Button";
 import { Icon } from "@/components/shared/Icon";
 import { useEffect } from "react";
+import { createPortal } from "react-dom";
 import { ModalProps } from "@/types/modal";
 import { modalConfigs } from "@/config/modalConfigs";
 
-const modalClasses = clsx(
-  "fixed left-1/2 top-1/2 transform -translate-x-1/2 -translate-y-1/2 z-40",
-  "w-full h-full",
-  "flex items-center"
-);
-
 const modalInnerClasses = clsx(
-  "relative m-auto w-xl min-h-68 py-9 px-7",
+  "relative w-[calc(100%-2rem)] max-w-xl min-h-(--fluid-modal-min-h)",
+  "py-(--fluid-modal-py) px-(--fluid-modal-px)",
   "flex flex-col items-center justify-center",
   "border border-gray-100 dark:border-gray-700 rounded-2xl shadow-sm bg-white dark:bg-gray-800"
 );
@@ -39,24 +35,20 @@ export default function Modal({
   const config: any = type
     ? modalConfigs[type as keyof typeof modalConfigs]
     : { title: undefined, description: undefined, warning: undefined };
-  // prop으로 전달받은 title, description이 있다면 사용하고, 없으면 config 값 사용
   const finalTitle = title ?? config.title;
   const finalDescription = description ?? config.description;
   const finalWarning = warning ?? config.warning;
 
-  // 성공 타입은 5초 자동 닫힘
   useEffect(() => {
     if (type === "success" || type === "deleteSuccess") {
       const timer = setTimeout(() => {
         onClose();
       }, 5000);
-
       return () => clearTimeout(timer);
     }
     return undefined;
   }, [type, onClose]);
 
-  // body 스크롤 방지
   useEffect(() => {
     if (isOpen) {
       document.body.style.overflow = "hidden";
@@ -66,14 +58,12 @@ export default function Modal({
     };
   }, [isOpen]);
 
-  // ESC 키로 모달 닫기
   useEffect(() => {
     const handleEscKey = (e: KeyboardEvent) => {
       if (e.key === "Escape" && isOpen) {
         onClose();
       }
     };
-
     window.addEventListener("keydown", handleEscKey);
     return () => window.removeEventListener("keydown", handleEscKey);
   }, [isOpen, onClose]);
@@ -82,84 +72,85 @@ export default function Modal({
     return null;
   }
 
-  return (
-    <div className={modalClasses}>
+  return createPortal(
+    <>
+      {/* backdrop */}
       <div
-        className="fixed inset-0 bg-black/50 dark:bg-black/70"
+        className="fixed inset-0 z-200 bg-black/50 dark:bg-black/70"
         onClick={onClose}
       />
-      <div className={modalInnerClasses}>
-        {/* 모달 아이콘 */}
-        {config?.icon && (
-          <div className={modalIconClasses}>
-            <Icon
-              type={config.icon}
-              className={`${config.iconColor}`}
-              size={config.iconSize}
-            />
-          </div>
-        )}
-        {/* 닫기 버튼 */}
-        <button
-          onClick={onClose}
-          className="absolute top-3 right-3 text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-gray-200"
-        >
-          <Icon type="x" />
-        </button>
-
-        {/* 텍스트 또는 커스텀 컨텐츠 */}
-        <div className="text-center w-full">
-          {children ? (
-            children
-          ) : (
-            <>
-              <h2 className="text-2xl font-bold text-gray-900 dark:text-gray-100">
-                {finalTitle}
-              </h2>
-              <p className="text-base font-medium mt-2 text-gray-700 dark:text-gray-300">
-                {finalDescription}
-              </p>
+      {/* modal */}
+      <div className="fixed inset-0 z-201 flex items-center justify-center">
+        <div className={modalInnerClasses}>
+          {config?.icon && (
+            <div className={modalIconClasses}>
+              <Icon
+                type={config.icon}
+                className={`${config.iconColor}`}
+                size={config.iconSize}
+              />
+            </div>
+          )}
+          <button
+            onClick={onClose}
+            className="absolute top-3 right-3 text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-gray-200"
+          >
+            <Icon type="x" />
+          </button>
 
-              {finalWarning && (
-                <p className="text-sm font-semibold mt-5 text-red-500 dark:text-red-400">
-                  {finalWarning}
+          <div className="text-center w-full">
+            {children ? (
+              children
+            ) : (
+              <>
+                <h2 className="text-2xl font-bold text-gray-900 dark:text-gray-100">
+                  {finalTitle}
+                </h2>
+                <p className="text-base font-medium mt-2 text-gray-700 dark:text-gray-300">
+                  {finalDescription}
                 </p>
-              )}
 
-              {config?.info && (
-                <p
-                  className={`text-sm font-medium mt-5 ${
-                    config.infoColor || "text-gray-600 dark:text-gray-400"
-                  }`}
+                {finalWarning && (
+                  <p className="text-sm font-semibold mt-5 text-red-500 dark:text-red-400">
+                    {finalWarning}
+                  </p>
+                )}
+
+                {config?.info && (
+                  <p
+                    className={`text-sm font-medium mt-5 ${
+                      config.infoColor || "text-gray-600 dark:text-gray-400"
+                    }`}
+                  >
+                    {config.info}
+                  </p>
+                )}
+              </>
+            )}
+          </div>
+
+          {(config?.buttonCancelText || config?.buttonConfirmText) && (
+            <div className="flex gap-3 justify-center mt-6">
+              {config?.buttonCancelText && (
+                <Button btnType="basic" variant="basic" onClick={onClose}>
+                  {config.buttonCancelText}
+                </Button>
+              )}
+              {config?.buttonConfirmText && (
+                <Button
+                  btnType="basic"
+                  variant="warning"
+                  onClick={onConfirm}
+                  disabled={buttonDisabled ?? config.buttonDisabled}
                 >
-                  {config.info}
-                </p>
+                  {config.buttonConfirmText}
+                </Button>
               )}
-            </>
+            </div>
           )}
         </div>
-
-        {/* 버튼 */}
-        {(config?.buttonCancelText || config?.buttonConfirmText) && (
-          <div className="flex gap-3 justify-center mt-6">
-            {config?.buttonCancelText && (
-              <Button btnType="basic" variant="basic" onClick={onClose}>
-                {config.buttonCancelText}
-              </Button>
-            )}
-            {config?.buttonConfirmText && (
-              <Button
-                btnType="basic"
-                variant="warning"
-                onClick={onConfirm}
-                disabled={buttonDisabled ?? config.buttonDisabled}
-              >
-                {config.buttonConfirmText}
-              </Button>
-            )}
-          </div>
-        )}
       </div>
-    </div>
+    </>,
+    document.body
   );
 }
diff --git a/src/components/ui/shadcn/Textarea.tsx b/src/components/ui/shadcn/Textarea.tsx
index 8c1c2df..20e4374 100644
--- a/src/components/ui/shadcn/Textarea.tsx
+++ b/src/components/ui/shadcn/Textarea.tsx
@@ -2,14 +2,32 @@ import * as React from "react";
 
 import { cn } from "@/lib/utils/utils";
 
-function Textarea({ className, ...props }: React.ComponentProps<"textarea">) {
+function Textarea({ className, onChange, ...props }: React.ComponentProps<"textarea">) {
+  const ref = React.useRef<HTMLTextAreaElement>(null);
+
+  const autoResize = (el: HTMLTextAreaElement) => {
+    el.style.height = "auto";
+    el.style.height = `${el.scrollHeight}px`;
+  };
+
+  React.useEffect(() => {
+    if (ref.current) autoResize(ref.current);
+  }, [props.value, props.defaultValue]);
+
+  const handleChange = (e: React.ChangeEvent<HTMLTextAreaElement>) => {
+    autoResize(e.target);
+    onChange?.(e);
+  };
+
   return (
     <textarea
+      ref={ref}
       data-slot="textarea"
       className={cn(
-        "border-input placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-ring/50 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:bg-input/30 flex field-sizing-content min-h-16 w-full rounded-md border bg-transparent px-3 py-3 text-base shadow-xs transition-[color,box-shadow] outline-none focus-visible:ring-[3px] disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+        "border-input placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-ring/50 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:bg-input/30 flex min-h-16 w-full rounded-md border bg-transparent px-3 py-3 text-base shadow-xs transition-[color,box-shadow] outline-none focus-visible:ring-[3px] disabled:cursor-not-allowed disabled:opacity-50 md:text-sm resize-none overflow-hidden",
         className
       )}
+      onChange={handleChange}
       {...props}
     />
   );
diff --git a/src/features/project/ui/ProjectCreationModal.tsx b/src/features/project/ui/ProjectCreationModal.tsx
index 92f5a61..87a06f2 100644
--- a/src/features/project/ui/ProjectCreationModal.tsx
+++ b/src/features/project/ui/ProjectCreationModal.tsx
@@ -169,7 +169,7 @@ export function ProjectCreationModal({ open, onOpenChange }: ProjectCreationModa
   return (
     <Dialog.Root open={open} onOpenChange={onOpenChange}>
       <Dialog.Portal>
-        <Dialog.Overlay className="fixed inset-0 bg-black/40 backdrop-blur-sm z-50 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0" />
+        <Dialog.Overlay className="fixed inset-0 bg-black/50 supports-backdrop-filter:bg-black/40 supports-backdrop-filter:backdrop-blur-sm z-50 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0" />
         <Dialog.Content className="fixed left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2 bg-card rounded-[14px] shadow-[0px_1px_3px_0px_rgba(0,0,0,0.1),0px_1px_2px_-1px_rgba(0,0,0,0.1)] border border-border z-50 w-[calc(100%-2rem)] sm:w-full max-w-[560px] max-h-[90vh] overflow-y-auto">
           <Dialog.Title className="sr-only">프로젝트 생성</Dialog.Title>
           {/* 헤더 */}