보스 결정 관리 페이지(프론트) 추가

- 보스 추가/편집/삭제 폼 (이름, 이미지, 난이도별 가격/인원)
- BossList: 등록된 보스 카드 목록 + 추가 버튼
- 동적 라우트가 sub-path 지원하도록 변경 (:slug/*)
- 커스텀 Checkbox/Select 컴포넌트
- number input 화살표 전역 제거
- 가격 입력 시 메소 단위 미리보기 표시
- 결정석 → 결정으로 용어 통일

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/App.jsx

@@ -20,11 +20,11 @@ export default function App() {
           <Route path="images" element={<AdminImages />} />
           <Route path="menus/new" element={<AdminMenuForm />} />
           <Route path="menus/:id" element={<AdminMenuForm />} />
-          <Route path=":slug" element={<AdminFeaturePage />} />
+          <Route path=":slug/*" element={<AdminFeaturePage />} />
         </Route>
 
         {/* 동적 기능 페이지 */}
-        <Route path="/:slug" element={<FeaturePage />} />
+        <Route path="/:slug/*" element={<FeaturePage />} />
       </Route>
     </Routes>
   )

frontend/src/components/Checkbox.jsx

@@ -0,0 +1,29 @@
+/**
+ * 커스텀 체크박스
+ * <Checkbox checked={x} onChange={(checked) => ...} />
+ */
+export default function Checkbox({ checked, onChange, disabled, className = '', size = 'md' }) {
+  const sizeCls = size === 'sm' ? 'w-4 h-4' : 'w-5 h-5'
+  const iconSize = size === 'sm' ? 'text-[10px]' : 'text-xs'
+
+  return (
+    <button
+      type="button"
+      role="checkbox"
+      aria-checked={checked}
+      disabled={disabled}
+      onClick={(e) => { e.stopPropagation(); !disabled && onChange?.(!checked) }}
+      className={`${sizeCls} shrink-0 rounded-md border-2 flex items-center justify-center transition ${
+        checked
+          ? 'border-emerald-500 bg-emerald-500 text-white'
+          : 'border-white/20 bg-gray-950 hover:border-white/40'
+      } ${disabled ? 'opacity-40 cursor-not-allowed' : 'cursor-pointer'} ${className}`}
+    >
+      {checked && (
+        <svg className={iconSize} viewBox="0 0 12 12" fill="none" xmlns="http://www.w3.org/2000/svg">
+          <path d="M2.5 6L5 8.5L9.5 4" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"/>
+        </svg>
+      )}
+    </button>
+  )
+}

frontend/src/components/Select.jsx

@@ -0,0 +1,69 @@
+import { useEffect, useRef, useState } from 'react'
+
+/**
+ * 커스텀 드롭다운 셀렉트
+ * <Select value={x} onChange={...} options={[{value, label}]} />
+ */
+export default function Select({ value, onChange, options, disabled, className = '', placeholder = '선택', align = 'left' }) {
+  const [open, setOpen] = useState(false)
+  const ref = useRef(null)
+
+  useEffect(() => {
+    if (!open) return
+    const handler = (e) => {
+      if (!ref.current?.contains(e.target)) setOpen(false)
+    }
+    document.addEventListener('mousedown', handler)
+    return () => document.removeEventListener('mousedown', handler)
+  }, [open])
+
+  const selected = options.find((o) => o.value === value)
+
+  return (
+    <div ref={ref} className={`relative ${className}`}>
+      <button
+        type="button"
+        disabled={disabled}
+        onClick={() => !disabled && setOpen((v) => !v)}
+        className={`w-full flex items-center justify-between gap-2 rounded-lg border bg-gray-950 px-3 py-2 text-sm transition outline-none ${
+          open ? 'border-emerald-500/50' : 'border-white/10 hover:border-white/20'
+        } ${disabled ? 'opacity-50 cursor-not-allowed' : ''}`}
+      >
+        <span className={selected ? '' : 'text-gray-500'}>
+          {selected ? selected.label : placeholder}
+        </span>
+        <svg className={`w-3.5 h-3.5 text-gray-500 transition ${open ? 'rotate-180' : ''}`} viewBox="0 0 12 12" fill="none">
+          <path d="M3 4.5L6 7.5L9 4.5" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
+        </svg>
+      </button>
+
+      {open && (
+        <div className={`absolute top-full mt-1 z-20 min-w-full rounded-lg border border-white/10 bg-gray-900 shadow-xl overflow-hidden ${
+          align === 'right' ? 'right-0' : 'left-0'
+        }`}>
+          <div className="max-h-60 overflow-y-auto py-1">
+            {options.map((opt) => (
+              <button
+                key={opt.value}
+                type="button"
+                onClick={() => { onChange(opt.value); setOpen(false) }}
+                className={`w-full text-left px-3 py-1.5 text-sm transition flex items-center gap-2 ${
+                  opt.value === value
+                    ? 'bg-emerald-500/10 text-emerald-300'
+                    : 'hover:bg-white/5'
+                }`}
+              >
+                {opt.value === value && (
+                  <svg className="w-3 h-3 shrink-0" viewBox="0 0 12 12" fill="none">
+                    <path d="M2.5 6L5 8.5L9.5 4" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"/>
+                  </svg>
+                )}
+                <span className={opt.value !== value ? 'pl-5' : ''}>{opt.label}</span>
+              </button>
+            ))}
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}

frontend/src/features/boss-crystal/BossCrystal.jsx

@@ -1,7 +1,7 @@
 export default function BossCrystal() {
   return (
     <div className="space-y-4">
-      <h1 className="text-2xl font-bold">주간 보스 결정석 계산기</h1>
+      <h1 className="text-2xl font-bold">주간 보스 결정 계산기</h1>
       <p className="text-gray-400">준비 중입니다.</p>
     </div>
   )

frontend/src/features/boss-crystal/BossCrystalAdmin.jsx

@@ -1,11 +1,13 @@
+import { Routes, Route } from 'react-router-dom'
+import BossList from './admin/BossList'
+import BossForm from './admin/BossForm'
+
 export default function BossCrystalAdmin() {
   return (
-    <div className="space-y-4">
+    <Routes>
-      <h2 className="text-lg font-semibold">보스 결정석 관리</h2>
+      <Route index element={<BossList />} />
-      <p className="text-sm text-gray-500">보스 정보 및 결정석 가격을 관리합니다</p>
+      <Route path="bosses/new" element={<BossForm />} />
-      <div className="rounded-2xl border border-white/5 bg-gray-900/40 p-12 text-center text-gray-500">
+      <Route path="bosses/:id" element={<BossForm />} />
-        준비 중
+    </Routes>
-      </div>
-    </div>
   )
 }

frontend/src/features/boss-crystal/admin/BossForm.jsx

@@ -0,0 +1,337 @@
+import { useState, useEffect, useRef } from 'react'
+import { useNavigate, useParams } from 'react-router-dom'
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
+import { api } from '../../../api/client'
+import ConfirmDialog from '../../../components/ConfirmDialog'
+import Checkbox from '../../../components/Checkbox'
+import Select from '../../../components/Select'
+import { DIFFICULTIES, formatMeso, getDifficultyImageUrl } from './constants'
+
+const PARTY_OPTIONS = [1, 2, 3, 4, 5, 6].map((n) => ({ value: n, label: `${n}인` }))
+
+function Field({ label, hint, error, required, children }) {
+  return (
+    <div className="space-y-1.5">
+      <div className="flex items-baseline justify-between">
+        <label className="text-sm font-medium text-gray-300">
+          {label} {required && <span className="text-red-400">*</span>}
+        </label>
+        {hint && <span className="text-xs text-gray-500">{hint}</span>}
+      </div>
+      {children}
+      {error && <div className="text-[11px] text-red-400">{error}</div>}
+    </div>
+  )
+}
+
+const inputCls = 'w-full rounded-lg border border-white/10 bg-gray-950 px-3 py-2 text-sm outline-none focus:border-emerald-500/50 transition'
+
+function emptyDifficultyState() {
+  const obj = {}
+  DIFFICULTIES.forEach((d) => {
+    obj[d.key] = { enabled: false, crystal_price: '', max_party_size: 6 }
+  })
+  return obj
+}
+
+export default function BossForm() {
+  const navigate = useNavigate()
+  const queryClient = useQueryClient()
+  const { id } = useParams()
+  const isEdit = !!id
+  const fileInputRef = useRef(null)
+
+  const [name, setName] = useState('')
+  const [imageFile, setImageFile] = useState(null)
+  const [imagePreview, setImagePreview] = useState(null)
+  const [existingImageUrl, setExistingImageUrl] = useState(null)
+  const [difficulties, setDifficulties] = useState(emptyDifficultyState())
+  const [errors, setErrors] = useState({})
+  const [confirmDelete, setConfirmDelete] = useState(false)
+
+  // 편집 모드 데이터 로드
+  const { data: bossData } = useQuery({
+    queryKey: ['admin', 'boss-crystal', 'bosses', id],
+    queryFn: () => api(`/api/admin/boss-crystal/bosses/${id}`),
+    enabled: isEdit,
+  })
+
+  useEffect(() => {
+    if (!isEdit) {
+      setName('')
+      setImageFile(null)
+      setImagePreview(null)
+      setExistingImageUrl(null)
+      setDifficulties(emptyDifficultyState())
+      return
+    }
+    if (bossData) {
+      setName(bossData.name || '')
+      setExistingImageUrl(bossData.image_url || null)
+      setImagePreview(null)
+      setImageFile(null)
+
+      const next = emptyDifficultyState()
+      bossData.difficulties?.forEach((d) => {
+        next[d.difficulty] = {
+          enabled: true,
+          crystal_price: String(d.crystal_price),
+          max_party_size: d.max_party_size,
+        }
+      })
+      setDifficulties(next)
+    }
+  }, [isEdit, id, bossData])
+
+  const handleImagePick = (file) => {
+    if (!file || !file.type.startsWith('image/')) return
+    setImageFile(file)
+    const reader = new FileReader()
+    reader.onload = (e) => setImagePreview(e.target.result)
+    reader.readAsDataURL(file)
+  }
+
+  const updateDifficulty = (key, patch) => {
+    setDifficulties((prev) => ({ ...prev, [key]: { ...prev[key], ...patch } }))
+  }
+
+  const validate = () => {
+    const errs = {}
+    if (!name.trim()) errs.name = '보스 이름을 입력해주세요'
+    if (!isEdit && !imageFile) errs.image = '보스 이미지를 업로드해주세요'
+
+    const enabledKeys = DIFFICULTIES.filter((d) => difficulties[d.key].enabled)
+    if (enabledKeys.length === 0) {
+      errs.difficulties = '하나 이상의 난이도를 선택해주세요'
+    } else {
+      for (const d of enabledKeys) {
+        const v = difficulties[d.key]
+        const price = Number(v.crystal_price)
+        if (!v.crystal_price || isNaN(price) || price <= 0) {
+          errs[`price_${d.key}`] = '가격을 입력해주세요'
+        }
+      }
+    }
+
+    setErrors(errs)
+    return Object.keys(errs).length === 0
+  }
+
+  const saveMutation = useMutation({
+    mutationFn: async () => {
+      const formData = new FormData()
+      formData.append('name', name.trim())
+      if (imageFile) formData.append('image', imageFile)
+
+      const diffsPayload = DIFFICULTIES
+        .filter((d) => difficulties[d.key].enabled)
+        .map((d) => ({
+          difficulty: d.key,
+          crystal_price: Number(difficulties[d.key].crystal_price),
+          max_party_size: Number(difficulties[d.key].max_party_size),
+        }))
+      formData.append('difficulties', JSON.stringify(diffsPayload))
+
+      const adminKey = localStorage.getItem('maple-admin-key')
+      const url = isEdit
+        ? `/api/admin/boss-crystal/bosses/${id}`
+        : '/api/admin/boss-crystal/bosses'
+      const res = await fetch(url, {
+        method: isEdit ? 'PATCH' : 'POST',
+        headers: { 'x-admin-key': adminKey },
+        body: formData,
+      })
+      const json = await res.json()
+      if (!res.ok) throw new Error(json.error || '저장 실패')
+      return json
+    },
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['admin', 'boss-crystal', 'bosses'] })
+      queryClient.invalidateQueries({ queryKey: ['boss-crystal'] })
+      navigate('..')
+    },
+    onError: (err) => alert(err.message),
+  })
+
+  const deleteMutation = useMutation({
+    mutationFn: () => api(`/api/admin/boss-crystal/bosses/${id}`, { method: 'DELETE' }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['admin', 'boss-crystal', 'bosses'] })
+      queryClient.invalidateQueries({ queryKey: ['boss-crystal'] })
+      navigate('..')
+    },
+    onError: (err) => alert(err.message),
+  })
+
+  const handleSubmit = (e) => {
+    e.preventDefault()
+    if (!validate()) return
+    saveMutation.mutate()
+  }
+
+  const displayImage = imagePreview || existingImageUrl
+
+  return (
+    <div className="space-y-6 max-w-2xl">
+      <div>
+        <h2 className="text-lg font-semibold">{isEdit ? '보스 편집' : '보스 추가'}</h2>
+        <p className="text-sm text-gray-500 mt-0.5">보스 이름과 난이도별 결정 정보를 입력합니다</p>
+      </div>
+
+      <form onSubmit={handleSubmit} className="space-y-5 rounded-2xl border border-white/5 bg-gray-900/40 p-6">
+        {/* 이름 */}
+        <Field label="보스 이름" required error={errors.name}>
+          <input
+            type="text"
+            value={name}
+            onChange={(e) => setName(e.target.value)}
+            placeholder="예: 검은 마법사"
+            className={inputCls}
+          />
+        </Field>
+
+        {/* 이미지 */}
+        <Field label="보스 이미지" required={!isEdit} error={errors.image}>
+          <label
+            className={`flex items-center gap-4 rounded-xl border-2 border-dashed bg-gray-950/50 p-4 transition cursor-pointer ${
+              errors.image
+                ? 'border-red-500/40'
+                : 'border-white/10 hover:border-emerald-500/40 hover:bg-emerald-500/5'
+            }`}
+          >
+            <div className="w-32 h-32 rounded-lg bg-gray-900 border border-white/5 flex items-center justify-center overflow-hidden shrink-0">
+              {displayImage ? (
+                <img src={displayImage} alt="" className="w-full h-full object-cover" />
+              ) : (
+                <span className="text-5xl text-gray-700">+</span>
+              )}
+            </div>
+            <div className="flex-1 min-w-0">
+              <div className="text-sm font-medium text-gray-300">
+                {displayImage ? '클릭하여 이미지 변경' : '클릭하여 이미지 업로드'}
+              </div>
+              <p className="text-xs text-gray-500 mt-1">PNG, JPG, GIF 등 → WebP로 자동 변환됩니다</p>
+              {imageFile && (
+                <div className="text-xs text-emerald-400 mt-2 truncate">📎 {imageFile.name}</div>
+              )}
+            </div>
+            <input
+              ref={fileInputRef}
+              type="file"
+              accept="image/*"
+              onChange={(e) => handleImagePick(e.target.files[0])}
+              className="hidden"
+            />
+          </label>
+        </Field>
+
+        {/* 난이도 */}
+        <Field label="난이도별 결정 정보" required error={errors.difficulties} hint="활성화한 난이도만 저장됩니다">
+          <div className="space-y-2">
+            {DIFFICULTIES.map((d) => {
+              const v = difficulties[d.key]
+              const priceErr = errors[`price_${d.key}`]
+              return (
+                <div
+                  key={d.key}
+                  className={`rounded-lg border bg-gray-950/50 p-3 transition ${
+                    v.enabled ? 'border-white/10' : 'border-white/5 opacity-60'
+                  }`}
+                >
+                  <div className="flex items-center gap-3">
+                    {/* 체크박스 + 난이도 이미지 (이미지 클릭으로도 토글 가능) */}
+                    <div
+                      className="flex items-center gap-2.5 shrink-0 cursor-pointer select-none"
+                      onClick={() => updateDifficulty(d.key, { enabled: !v.enabled })}
+                    >
+                      <Checkbox
+                        checked={v.enabled}
+                        onChange={(checked) => updateDifficulty(d.key, { enabled: checked })}
+                      />
+                      <img
+                        src={getDifficultyImageUrl(d.key)}
+                        alt={d.label}
+                        className="h-5"
+                        onError={(e) => { e.currentTarget.style.display = 'none' }}
+                      />
+                    </div>
+
+                    {/* 가격 */}
+                    <div className="flex-1 min-w-0">
+                      <div className="relative">
+                        <input
+                          type="number"
+                          value={v.crystal_price}
+                          onChange={(e) => updateDifficulty(d.key, { crystal_price: e.target.value })}
+                          disabled={!v.enabled}
+                          placeholder="결정 가격"
+                          className={`w-full rounded-lg border bg-gray-900 pl-4 pr-28 py-2 text-sm outline-none focus:border-emerald-500/50 disabled:opacity-50 disabled:cursor-not-allowed transition ${
+                            priceErr ? 'border-red-500/40' : 'border-white/10'
+                          }`}
+                        />
+                        {v.crystal_price && v.enabled && (
+                          <span className="absolute right-3 top-1/2 -translate-y-1/2 text-sm text-emerald-400/80 pointer-events-none whitespace-nowrap">
+                            {formatMeso(Number(v.crystal_price))}
+                          </span>
+                        )}
+                      </div>
+                    </div>
+
+                    {/* 최대 인원 */}
+                    <Select
+                      value={v.max_party_size}
+                      onChange={(val) => updateDifficulty(d.key, { max_party_size: val })}
+                      options={PARTY_OPTIONS}
+                      disabled={!v.enabled}
+                      className="w-20 shrink-0"
+                      align="right"
+                    />
+                  </div>
+                </div>
+              )
+            })}
+          </div>
+        </Field>
+
+        {/* 버튼 */}
+        <div className="flex items-center gap-2 pt-2">
+          {isEdit && (
+            <button
+              type="button"
+              onClick={() => setConfirmDelete(true)}
+              className="rounded-lg border border-red-500/30 text-red-400 hover:bg-red-500/10 hover:border-red-500/50 px-4 py-2.5 text-sm transition"
+            >
+              삭제
+            </button>
+          )}
+          <div className="flex-1" />
+          <button
+            type="button"
+            onClick={() => navigate('..')}
+            className="rounded-lg border border-white/10 px-5 py-2.5 text-sm hover:bg-white/5 transition"
+          >
+            취소
+          </button>
+          <button
+            type="submit"
+            disabled={saveMutation.isPending}
+            className="rounded-lg bg-emerald-600 hover:bg-emerald-500 px-5 py-2.5 text-sm font-medium disabled:opacity-50 transition shadow-lg shadow-emerald-500/20"
+          >
+            {saveMutation.isPending ? '저장 중...' : (isEdit ? '저장' : '추가')}
+          </button>
+        </div>
+      </form>
+
+      <ConfirmDialog
+        open={confirmDelete}
+        onClose={() => setConfirmDelete(false)}
+        onConfirm={() => deleteMutation.mutate()}
+        title="보스 삭제"
+        description={`"${name}" 보스를 삭제하시겠습니까?\n\n이 작업은 되돌릴 수 없습니다.`}
+        confirmText="삭제"
+        destructive
+        loading={deleteMutation.isPending}
+      />
+    </div>
+  )
+}

frontend/src/features/boss-crystal/admin/BossList.jsx

@@ -0,0 +1,78 @@
+import { Link } from 'react-router-dom'
+import { useQuery } from '@tanstack/react-query'
+import { api } from '../../../api/client'
+import { DIFFICULTIES, formatMeso, getDifficultyImageUrl } from './constants'
+
+export default function BossList() {
+  const { data: bosses = [], isLoading } = useQuery({
+    queryKey: ['admin', 'boss-crystal', 'bosses'],
+    queryFn: () => api('/api/admin/boss-crystal/bosses').catch(() => []),
+  })
+
+  return (
+    <div className="space-y-6">
+      <div className="flex items-end justify-between gap-4 flex-wrap">
+        <div>
+          <h2 className="text-lg font-semibold">보스 결정 관리</h2>
+          <p className="text-sm text-gray-500 mt-0.5">보스 정보 및 난이도별 결정 가격을 관리합니다</p>
+        </div>
+        <Link
+          to="bosses/new"
+          className="flex items-center gap-1.5 rounded-lg bg-emerald-600 hover:bg-emerald-500 px-4 py-2 text-sm font-medium transition shadow-lg shadow-emerald-500/20"
+        >
+          <span className="text-base leading-none">+</span>
+          보스 추가
+        </Link>
+      </div>
+
+      {isLoading ? (
+        <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
+          {Array.from({ length: 4 }).map((_, i) => (
+            <div key={i} className="h-32 rounded-2xl bg-white/[0.02] animate-pulse" />
+          ))}
+        </div>
+      ) : bosses.length === 0 ? (
+        <div className="rounded-2xl border border-dashed border-white/10 bg-white/[0.02] p-16 text-center">
+          <div className="text-5xl mb-3 opacity-30">⚔️</div>
+          <p className="text-gray-400 mb-4">등록된 보스가 없습니다</p>
+          <Link to="bosses/new" className="text-sm text-emerald-400 hover:text-emerald-300 transition">
+            첫 보스 추가하기 →
+          </Link>
+        </div>
+      ) : (
+        <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
+          {bosses.map((boss) => (
+            <Link
+              key={boss.id}
+              to={`bosses/${boss.id}`}
+              className="group rounded-2xl border border-white/5 bg-gradient-to-br from-gray-900/80 to-gray-900/40 p-4 hover:border-emerald-500/30 transition"
+            >
+              <div className="flex items-start gap-3">
+                <div className="shrink-0 w-14 h-14 rounded-xl bg-gradient-to-br from-gray-800 to-gray-900 border border-white/5 flex items-center justify-center overflow-hidden">
+                  <img
+                    src={boss.image_url || '/default.png'}
+                    alt={boss.name}
+                    className="max-w-full max-h-full object-contain"
+                  />
+                </div>
+                <div className="flex-1 min-w-0">
+                  <h3 className="font-semibold group-hover:text-emerald-300 transition truncate">{boss.name}</h3>
+                  <div className="flex flex-wrap gap-1 mt-2">
+                    {DIFFICULTIES.filter((d) => boss.difficulties?.some((bd) => bd.difficulty === d.key)).map((d) => {
+                      const bd = boss.difficulties.find((x) => x.difficulty === d.key)
+                      return (
+                        <span key={d.key} className={`text-[10px] px-1.5 py-0.5 rounded border ${d.color}`} title={`${formatMeso(bd.crystal_price)} / ${bd.max_party_size}인`}>
+                          {d.label}
+                        </span>
+                      )
+                    })}
+                  </div>
+                </div>
+              </div>
+            </Link>
+          ))}
+        </div>
+      )}
+    </div>
+  )
+}

frontend/src/features/boss-crystal/admin/constants.js

@@ -0,0 +1,24 @@
+// 난이도 정의 (key, label, color)
+export const DIFFICULTIES = [
+  { key: 'easy', label: '이지', color: 'text-green-400 border-green-500/30 bg-green-500/10' },
+  { key: 'normal', label: '노말', color: 'text-gray-300 border-gray-500/30 bg-gray-500/10' },
+  { key: 'hard', label: '하드', color: 'text-rose-400 border-rose-500/30 bg-rose-500/10' },
+  { key: 'chaos', label: '카오스', color: 'text-amber-400 border-amber-500/30 bg-amber-500/10' },
+  { key: 'extreme', label: '익스트림', color: 'text-red-500 border-red-500/30 bg-red-500/10' },
+]
+
+export function formatMeso(n) {
+  if (!n || n < 10000) return (n || 0).toLocaleString()
+  if (n >= 100_000_000) {
+    const uk = Math.floor(n / 100_000_000)
+    const man = Math.floor((n % 100_000_000) / 10_000)
+    return man > 0 ? `${uk}억 ${man.toLocaleString()}만` : `${uk}억`
+  }
+  return `${Math.floor(n / 10_000).toLocaleString()}만`
+}
+
+// difficulty 이미지 URL (S3)
+export const DIFFICULTY_IMAGE_BASE = 'https://s3.caadiq.co.kr/maplestory/crystal/difficulty'
+export function getDifficultyImageUrl(key) {
+  return `${DIFFICULTY_IMAGE_BASE}/${key}.webp`
+}

frontend/src/index.css

@@ -24,3 +24,13 @@ a {
 button:disabled {
   cursor: not-allowed;
 }
+
+/* number input 화살표 숨기기 */
+input[type="number"]::-webkit-inner-spin-button,
+input[type="number"]::-webkit-outer-spin-button {
+  -webkit-appearance: none;
+  margin: 0;
+}
+input[type="number"] {
+  -moz-appearance: textfield;
+}