diff --git a/src/admin/achievement/components/AchievementModal.vue b/src/admin/achievement/components/AchievementModal.vue
index 7982a0e..676ba19 100644
--- a/src/admin/achievement/components/AchievementModal.vue
+++ b/src/admin/achievement/components/AchievementModal.vue
@@ -7,6 +7,12 @@ import {
   type MetricOption,
 } from "admin/api"
 import AchievementIcon from "shared/components/AchievementIcon.vue"
+import { RARITY_LABEL } from "utils/constants"
+
+const rarityOptions = Object.entries(RARITY_LABEL).map(([value, label]) => ({
+  label,
+  value,
+}))
 
 const props = defineProps<{
   show: boolean
@@ -118,15 +124,7 @@ async function save() {
         </n-flex>
       </n-form-item>
       <n-form-item label="稀有度">
-        <n-select
-          v-model:value="form.rarity"
-          :options="[
-            { label: '青铜', value: 'bronze' },
-            { label: '白银', value: 'silver' },
-            { label: '黄金', value: 'gold' },
-            { label: '白金', value: 'platinum' },
-          ]"
-        />
+        <n-select v-model:value="form.rarity" :options="rarityOptions" />
       </n-form-item>
       <n-form-item label="指标" required>
         <n-select
diff --git a/src/admin/achievement/list.vue b/src/admin/achievement/list.vue
index 68883b8..db6d265 100644
--- a/src/admin/achievement/list.vue
+++ b/src/admin/achievement/list.vue
@@ -7,6 +7,7 @@ import {
 } from "admin/api"
 import AchievementIcon from "shared/components/AchievementIcon.vue"
 import AchievementModal from "./components/AchievementModal.vue"
+import { RARITY_LABEL } from "utils/constants"
 
 const message = useMessage()
 const dialog = useDialog()
@@ -16,13 +17,6 @@ const loading = ref(false)
 const showModal = ref(false)
 const editing = ref<AdminAchievement | null>(null)
 
-const RARITY_LABEL: Record<string, string> = {
-  bronze: "青铜",
-  silver: "白银",
-  gold: "黄金",
-  platinum: "白金",
-}
-
 // 下架的只在有的时候才提，全部上架时标题不啰嗦
 const title = computed(() => {
   if (!list.value.length) return "成就管理"
diff --git a/src/oj/achievement/components/AchievementCard.vue b/src/oj/achievement/components/AchievementCard.vue
index 946fc61..d20b42b 100644
--- a/src/oj/achievement/components/AchievementCard.vue
+++ b/src/oj/achievement/components/AchievementCard.vue
@@ -1,22 +1,13 @@
 <script setup lang="ts">
 import AchievementIcon from "shared/components/AchievementIcon.vue"
+import { useRarityColor } from "shared/composables/rarity"
+import { RARITY_COLOR, RARITY_LABEL } from "utils/constants"
 import type { Achievement } from "utils/types"
 
 const props = defineProps<{ achievement: Achievement }>()
 
-const RARITY_COLOR: Record<string, string> = {
-  bronze: "#b87333",
-  silver: "#9fa6b2",
-  gold: "#e0a300",
-  platinum: "#7dd3fc",
-}
-
-const RARITY_LABEL: Record<string, string> = {
-  bronze: "青铜",
-  silver: "白银",
-  gold: "黄金",
-  platinum: "白金",
-}
+// 边框用原色，tag 里的文字用跟主题走的那套
+const rarityTextColor = useRarityColor()
 
 // 隐藏且未解锁：后端已把名称/描述/图标和条件三件套都遮成 ??? 和 null，
 // 这里只负责不要把 null 渲染出来，也不要画出会泄露门槛的进度条
@@ -78,7 +69,7 @@ const unlockDate = computed(() => {
             size="tiny"
             :color="{
               borderColor: RARITY_COLOR[achievement.rarity],
-              textColor: RARITY_COLOR[achievement.rarity],
+              textColor: rarityTextColor[achievement.rarity],
             }"
           >
             {{ RARITY_LABEL[achievement.rarity] }}
diff --git a/src/oj/achievement/index.vue b/src/oj/achievement/index.vue
index e22334c..736fee7 100644
--- a/src/oj/achievement/index.vue
+++ b/src/oj/achievement/index.vue
@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { getAchievements, getAchievementSummary } from "oj/achievement/api"
 import { getUserBadges } from "oj/api"
+import { useRarityColor } from "shared/composables/rarity"
 import type { Achievement, AchievementSummary } from "utils/types"
 import AchievementCard from "./components/AchievementCard.vue"
 
@@ -18,27 +19,8 @@ interface UserBadge {
 const route = useRoute()
 const name = computed(() => (route.query.name as string) || undefined)
 
-// 稀有度配色分明暗两套：AchievementCard 那组原色是照着深色底调的，
-// 直接拿到白底上，白金只有 1.7:1、黄金 2.2:1，小字根本看不清
-const isDark = useDark()
-
-const RARITY_COLOR_DARK: Record<string, string> = {
-  bronze: "#d18d4f",
-  silver: "#b6bcc7",
-  gold: "#e0a300",
-  platinum: "#7dd3fc",
-}
-
-const RARITY_COLOR_LIGHT: Record<string, string> = {
-  bronze: "#9a5b25",
-  silver: "#6b7280",
-  gold: "#a37500",
-  platinum: "#0284c7",
-}
-
-const rarityColor = computed(() =>
-  isDark.value ? RARITY_COLOR_DARK : RARITY_COLOR_LIGHT,
-)
+// 标签和进度条同色，整行读作一个单位
+const rarityColor = useRarityColor()
 
 const achievements = ref<Achievement[]>([])
 const summary = ref<AchievementSummary | null>(null)
diff --git a/src/shared/components/AchievementToast.vue b/src/shared/components/AchievementToast.vue
index c3bff66..1d83dc0 100644
--- a/src/shared/components/AchievementToast.vue
+++ b/src/shared/components/AchievementToast.vue
@@ -1,18 +1,12 @@
 <script setup lang="ts">
 import AchievementIcon from "shared/components/AchievementIcon.vue"
 import { useAchievementStore } from "shared/store/achievement"
+import { RARITY_COLOR } from "utils/constants"
 
 const store = useAchievementStore()
 const { current, queue } = storeToRefs(store)
 const visible = ref(false)
 
-const RARITY_COLOR: Record<string, string> = {
-  bronze: "#b87333",
-  silver: "#9fa6b2",
-  gold: "#e0a300",
-  platinum: "#7dd3fc",
-}
-
 let timer: ReturnType<typeof setTimeout> | null = null
 let gapTimer: ReturnType<typeof setTimeout> | null = null
 
diff --git a/src/shared/composables/rarity.ts b/src/shared/composables/rarity.ts
new file mode 100644
index 0000000..237170c
--- /dev/null
+++ b/src/shared/composables/rarity.ts
@@ -0,0 +1,15 @@
+import { useDark } from "@vueuse/core"
+import { computed } from "vue"
+import { RARITY_TEXT_COLOR } from "utils/constants"
+
+/**
+ * 成就稀有度的文字配色，跟随明暗主题切换。
+ * 两套色值都压到 4.5:1 以上，不然浅色模式下白金和黄金的小字看不清。
+ * 边框和色块不用这个，直接用 RARITY_COLOR 的原色。
+ */
+export function useRarityColor() {
+  const isDark = useDark()
+  return computed(() =>
+    isDark.value ? RARITY_TEXT_COLOR.dark : RARITY_TEXT_COLOR.light,
+  )
+}
diff --git a/src/utils/constants.ts b/src/utils/constants.ts
index bccd7c4..0a2559c 100644
--- a/src/utils/constants.ts
+++ b/src/utils/constants.ts
@@ -1,4 +1,4 @@
-import type { SUBMISSION_RESULT } from "./types"
+import type { AchievementRarity, SUBMISSION_RESULT } from "./types"
 
 export enum SubmissionStatus {
   compile_error = -2,
@@ -276,6 +276,42 @@ export enum ChartType {
   Activity,
 }
 
+// 成就稀有度
+export const RARITY_LABEL: Record<AchievementRarity, string> = {
+  bronze: "青铜",
+  silver: "白银",
+  gold: "黄金",
+  platinum: "白金",
+}
+
+// 边框、色块用的原色：饱和度够高，明暗底上都醒目
+export const RARITY_COLOR: Record<AchievementRarity, string> = {
+  bronze: "#b87333",
+  silver: "#9fa6b2",
+  gold: "#e0a300",
+  platinum: "#7dd3fc",
+}
+
+// 文字要另配一套。上面那组是照深色底调的，搬到白底上白金只有 1.7:1、
+// 黄金 2.2:1，12px 的稀有度标签根本看不清。取色见 useRarityColor
+export const RARITY_TEXT_COLOR: Record<
+  "dark" | "light",
+  Record<AchievementRarity, string>
+> = {
+  dark: {
+    bronze: "#d18d4f",
+    silver: "#b6bcc7",
+    gold: "#e0a300",
+    platinum: "#7dd3fc",
+  },
+  light: {
+    bronze: "#9a5b25",
+    silver: "#6b7280",
+    gold: "#a37500",
+    platinum: "#0284c7",
+  },
+}
+
 // 时间范围配置
 export const DURATION_OPTIONS = [
   { label: "本节课内", value: "hours:1" },