diff --git a/frontend/package.json b/frontend/package.json
index 85aafec..8bb5c9b 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -4,7 +4,7 @@
   "version": "0.1.0",
   "type": "module",
   "scripts": {
-    "test": "node --test src/App.test.js src/views/SetupWizard/SetupWizard.test.js src/views/SetupWizard/SetupWizardBootstrap.test.js src/views/SetupWizard/DatabaseSetup.test.js src/views/SetupWizard/BootstrapPayload.test.js src/views/Dashboard/Dashboard.test.js src/views/UserManagement/UserManagement.test.js",
+    "test": "node --test src/App.test.js src/views/SetupWizard/SetupWizard.test.js src/views/SetupWizard/SetupWizardBootstrap.test.js src/views/SetupWizard/DatabaseSetup.test.js src/views/SetupWizard/BootstrapPayload.test.js src/views/Dashboard/Dashboard.test.js src/views/UserManagement/UserManagement.test.js src/views/components/HelpTip/HelpTip.test.js",
     "dev": "vite",
     "build": "vite build",
     "preview": "vite preview"
diff --git a/frontend/src/views/SetupWizard/DatabaseSetup.vue b/frontend/src/views/SetupWizard/DatabaseSetup.vue
index 94236e0..3089728 100644
--- a/frontend/src/views/SetupWizard/DatabaseSetup.vue
+++ b/frontend/src/views/SetupWizard/DatabaseSetup.vue
@@ -1,4 +1,5 @@
 <script setup>
+import HelpTip from "../components/HelpTip/HelpTip.vue";
 defineProps({
   form: { type: Object, required: true },
   testing: Boolean,
@@ -32,8 +33,12 @@ const emit = defineEmits(["test"]);
       </div>
     </div>
     <div class="setup-section-heading">
-      <strong>数据库存储</strong>
-      <span>选择一种存储方式，验证连接和写权限后继续。不会清空已有数据。</span>
+      <strong>
+        数据库存储
+        <HelpTip>
+          选择一种存储方式，验证连接和写权限后继续。不会清空已有数据。
+        </HelpTip>
+      </strong>
     </div>
     <div v-if="form.driver !== 'sqlite'" class="setup-grid two-columns database-connection-grid">
       <label>
diff --git a/frontend/src/views/SetupWizard/SetupWizard.vue b/frontend/src/views/SetupWizard/SetupWizard.vue
index 5f9a5b7..c97eaa3 100644
--- a/frontend/src/views/SetupWizard/SetupWizard.vue
+++ b/frontend/src/views/SetupWizard/SetupWizard.vue
@@ -1,4 +1,5 @@
 <script setup>
+import HelpTip from "../components/HelpTip/HelpTip.vue";
 import { useSetupWizard } from "./SetupWizard.js";
 import AccessShell from "../components/AccessShell/AccessShell.vue";
 import DatabaseSetup from "./DatabaseSetup.vue";
@@ -142,8 +143,12 @@ const {
                   placeholder="例如 scert-admin"
               /></label>
               <label class="email-field"
-                ><span>绑定邮箱</span
-                ><div class="email-input-group">
+                ><span>
+                  绑定邮箱
+                  <HelpTip>
+                    可直接输入完整邮箱，也可先输入邮箱名称再选择常用邮箱。
+                  </HelpTip>
+                </span><div class="email-input-group">
                   <input
                     ref="emailAutofillElement"
                     class="email-autofill-probe"
@@ -188,7 +193,6 @@ const {
                     </option>
                   </select>
                 </div>
-                <small>可直接输入完整邮箱，也可先输入邮箱名称再选择常用邮箱。</small>
               </label>
               <label
                 ><span>密码</span
@@ -218,8 +222,12 @@ const {
               /></label>
             </div>
             <div class="setup-section-heading">
-              <strong>服务访问配置</strong>
-              <span>先确定 Scert 主服务和管理页面的访问方式，后续步骤会使用这里的配置。</span>
+              <strong>
+                服务访问配置
+                <HelpTip>
+                  先确定 Scert 主服务和管理页面的访问方式，后续步骤会使用这里的配置。
+                </HelpTip>
+              </strong>
             </div>
             <div class="setup-grid service-access-grid" :class="{ 'has-database': isBootstrap }">
               <div class="access-target-field">
@@ -264,7 +272,12 @@ const {
                 />
               </label>
               <label>
-                <span>Scert 主服务端口</span>
+                <span>
+                  Scert 主服务端口
+                  <HelpTip>
+                    管理页面和 API 对外提供服务使用的端口。
+                  </HelpTip>
+                </span>
                 <input
                   id="server-port"
                   name="server_port"
@@ -274,7 +287,6 @@ const {
                   max="65535"
                   type="number"
                 />
-                <small>管理页面和 API 对外提供服务使用的端口。</small>
               </label>
               <DatabaseSetup
                 v-if="isBootstrap"
@@ -300,8 +312,12 @@ const {
 
             <div class="notification-layout">
               <div class="notification-guide">
-                <strong>先完成基础配置</strong>
-                <span>填写邮件服务地址即可继续，其他项目已经提供合理默认值。</span>
+                <strong>
+                  先完成基础配置
+                  <HelpTip>
+                    填写邮件服务地址即可继续，其他项目已经提供合理默认值。
+                  </HelpTip>
+                </strong>
               </div>
 
               <div class="notification-row notification-service-row">
@@ -312,8 +328,12 @@ const {
                     type="checkbox"
                   />
                   <span>
-                    <strong>启用 HTTP 邮件通知</strong>
-                    <small>通过第三方邮件 API 发送任务通知。</small>
+                    <strong>
+                      启用 HTTP 邮件通知
+                      <HelpTip>
+                        通过第三方邮件 API 发送任务通知。
+                      </HelpTip>
+                    </strong>
                   </span>
                 </label>
                 <label class="confirm-row compact-row">
@@ -323,8 +343,12 @@ const {
                     type="checkbox"
                   />
                   <span>
-                    <strong>启用 SMTP 通知</strong>
-                    <small>通过 SMTP 出站客户端发送任务通知。</small>
+                    <strong>
+                      启用 SMTP 通知
+                      <HelpTip>
+                        通过 SMTP 出站客户端发送任务通知。
+                      </HelpTip>
+                    </strong>
                   </span>
                 </label>
               </div>
@@ -332,8 +356,12 @@ const {
               <div v-if="form.email_smtp_enabled" class="notification-basic-panel smtp-basic-panel">
                 <div class="notification-section-heading">
                   <div>
-                    <strong>SMTP 通知配置</strong>
-                    <span>Scert 只作为 SMTP 出站客户端，不提供 SMTP、IMAP 或 POP3 服务端。</span>
+                    <strong>
+                      SMTP 通知配置
+                      <HelpTip>
+                        Scert 只作为 SMTP 出站客户端，不提供 SMTP、IMAP 或 POP3 服务端。
+                      </HelpTip>
+                    </strong>
                   </div>
                   <span class="notification-recommended-badge">推荐 STARTTLS</span>
                 </div>
@@ -414,15 +442,24 @@ const {
               <div v-if="form.email_http_enabled" class="notification-basic-panel">
                 <div class="notification-section-heading">
                   <div>
-                    <strong>邮件通知基础配置</strong>
-                    <span>填写服务地址、发件人和收件人即可，技术参数无需修改。</span>
+                    <strong>
+                      邮件通知基础配置
+                      <HelpTip>
+                        填写服务地址、发件人和收件人即可，技术参数无需修改。
+                      </HelpTip>
+                    </strong>
                   </div>
                   <span class="notification-recommended-badge">推荐配置</span>
                 </div>
 
                 <div class="notification-row notification-basic-row">
                   <label>
-                    <span>邮件服务地址</span>
+                    <span>
+                      邮件服务地址
+                      <HelpTip>
+                        填写邮件服务提供的地址，不需要自行拼接接口路径。
+                      </HelpTip>
+                    </span>
                     <input
                       id="email-endpoint"
                       name="email_endpoint"
@@ -430,17 +467,20 @@ const {
                       type="url"
                       placeholder="https://mail.example.com"
                     />
-                    <small>填写邮件服务提供的地址，不需要自行拼接接口路径。</small>
                   </label>
                   <label>
-                    <span>邮件服务名称（可选）</span>
+                    <span>
+                      邮件服务名称（可选）
+                      <HelpTip>
+                        仅用于日志和通知内容中的识别。
+                      </HelpTip>
+                    </span>
                     <input
                       id="email-provider"
                       name="email_provider"
                       v-model.trim="form.email_provider"
                       placeholder="例如：Smail"
                     />
-                    <small>仅用于日志和通知内容中的识别。</small>
                   </label>
                 </div>
 
@@ -463,14 +503,18 @@ const {
                     />
                   </label>
                   <label>
-                    <span>通知收件人</span>
+                    <span>
+                      通知收件人
+                      <HelpTip>
+                        续期、部署和错误通知将发送到这些地址。
+                      </HelpTip>
+                    </span>
                     <input
                       id="recipients"
                       name="recipients"
                       v-model="form.recipients"
                       placeholder="多个地址使用逗号分隔"
                     />
-                    <small>续期、部署和错误通知将发送到这些地址。</small>
                   </label>
                 </div>
               </div>
@@ -689,22 +733,29 @@ const {
                 </select></label
               >
               <label
-                ><span>DNS 权限测试域名</span
-                ><input
+                ><span>
+                  DNS 权限测试域名
+                  <HelpTip>
+                    使用域名时可填写管理页面域名；使用公网 IP
+                    时必须另填一个由当前 DNS 账号管理的域名。
+                  </HelpTip>
+                </span><input
                   id="dns-test-domain"
                   name="dns_test_domain"
                   v-model.trim="dnsTestDomain"
                   required
                   placeholder="例如 example.com"
-                /><small
-                  >使用域名时可填写管理页面域名；使用公网 IP
-                  时必须另填一个由当前 DNS 账号管理的域名。</small
-                ></label
+                /></label
               >
             </div>
             <div class="setup-grid two-columns propagation-grid">
               <label>
-                <span>DNS 传播最大等待时间（秒）</span>
+                <span>
+                  DNS 传播最大等待时间（秒）
+                  <HelpTip>
+                    默认 300 秒，最长允许等待 86400 秒。
+                  </HelpTip>
+                </span>
                 <input
                   id="propagation-timeout-secs"
                   name="propagation_timeout_secs"
@@ -714,10 +765,14 @@ const {
                   max="86400"
                   required
                 />
-                <small>默认 300 秒，最长允许等待 86400 秒。</small>
               </label>
               <label>
-                <span>DNS 传播检测间隔（秒）</span>
+                <span>
+                  DNS 传播检测间隔（秒）
+                  <HelpTip>
+                    默认 5 秒，不能大于最大等待时间。
+                  </HelpTip>
+                </span>
                 <input
                   id="propagation-polling-interval-secs"
                   name="propagation_polling_interval_secs"
@@ -727,7 +782,6 @@ const {
                   :max="form.propagation_timeout_secs"
                   required
                 />
-                <small>默认 5 秒，不能大于最大等待时间。</small>
               </label>
             </div>
             <p class="field-hint">
@@ -935,8 +989,12 @@ const {
                 type="checkbox"
               />
               <span>
-                <strong>初始化完成后开启管理页面</strong>
-                <small>桌面端可通过此开关决定是否启用浏览器管理页面。</small>
+                <strong>
+                  初始化完成后开启管理页面
+                  <HelpTip>
+                    桌面端可通过此开关决定是否启用浏览器管理页面。
+                  </HelpTip>
+                </strong>
               </span>
             </label>
           </fieldset>
diff --git a/frontend/src/views/SetupWizard/SetupWizardLayout.css b/frontend/src/views/SetupWizard/SetupWizardLayout.css
index 83550c2..4af99f5 100644
--- a/frontend/src/views/SetupWizard/SetupWizardLayout.css
+++ b/frontend/src/views/SetupWizard/SetupWizardLayout.css
@@ -68,6 +68,14 @@
     line-height: 1.35;
   }
 
+  .access-shell--setup label:not(.confirm-row) > span,
+  .access-shell--setup .access-target-field > span {
+    display: flex;
+    align-items: center;
+    min-height: 20px;
+    line-height: 20px;
+  }
+
   .access-shell--setup input:not([type="checkbox"]),
   .access-shell--setup select {
     height: 36px;
@@ -149,7 +157,7 @@
     width: 92px;
     height: auto;
     min-height: 36px;
-    margin-top: calc(8px + 1.35 * 12px);
+    margin-top: 28px;
     white-space: normal;
     overflow-wrap: anywhere;
     padding: 6px 10px;
diff --git a/frontend/src/views/components/HelpTip/HelpTip.css b/frontend/src/views/components/HelpTip/HelpTip.css
new file mode 100644
index 0000000..d671a26
--- /dev/null
+++ b/frontend/src/views/components/HelpTip/HelpTip.css
@@ -0,0 +1,57 @@
+.help-tip-trigger {
+  display: inline-flex;
+  flex: 0 0 auto;
+  align-items: center;
+  justify-content: center;
+  box-sizing: border-box;
+  width: 17px;
+  height: 17px;
+  margin-left: 6px;
+  border: 1px solid #7d91ae;
+  border-radius: 50%;
+  color: #526b8e;
+  background: #f4f7fc;
+  font-size: 11px;
+  font-weight: 700;
+  line-height: 1;
+  vertical-align: middle;
+  cursor: help;
+  user-select: none;
+}
+
+.help-tip-trigger:hover,
+.help-tip-trigger:focus-visible {
+  border-color: #315faa;
+  color: #234f93;
+  background: #eaf1fc;
+}
+
+.help-tip-trigger:focus-visible {
+  outline: 2px solid #315faa;
+  outline-offset: 3px;
+}
+
+.help-tip-content {
+  position: fixed;
+  z-index: 10000;
+  display: block;
+  box-sizing: border-box;
+  width: max-content;
+  max-width: min(340px, calc(100vw - 24px));
+  max-height: calc(100dvh - 24px);
+  overflow: auto;
+  padding: 10px 12px;
+  border: 1px solid #334763;
+  border-radius: 8px;
+  color: #ffffff;
+  background: #25364f;
+  box-shadow: 0 6px 22px rgb(23 32 51 / 18%);
+  font-family: inherit;
+  font-size: 13px;
+  font-weight: 400;
+  line-height: 1.6;
+  letter-spacing: normal;
+  text-align: left;
+  white-space: normal;
+  overflow-wrap: anywhere;
+}
diff --git a/frontend/src/views/components/HelpTip/HelpTip.js b/frontend/src/views/components/HelpTip/HelpTip.js
new file mode 100644
index 0000000..7606be5
--- /dev/null
+++ b/frontend/src/views/components/HelpTip/HelpTip.js
@@ -0,0 +1,77 @@
+import { nextTick, onBeforeUnmount, onMounted, ref, useId } from "vue";
+import { placeTooltip } from "./HelpTipPosition.js";
+
+export function useHelpTip() {
+  const trigger = ref(null);
+  const tooltip = ref(null);
+  const visible = ref(false);
+  const position = ref({ left: "0px", top: "0px" });
+  const tooltipId = `help-tip-${useId()}`;
+  let timer;
+
+  function cancelHide() {
+    clearTimeout(timer);
+  }
+
+  function hide() {
+    cancelHide();
+    visible.value = false;
+  }
+
+  async function show() {
+    cancelHide();
+    visible.value = true;
+    await nextTick();
+    if (!visible.value || !trigger.value || !tooltip.value) return;
+    const point = placeTooltip(
+      trigger.value.getBoundingClientRect(),
+      tooltip.value.getBoundingClientRect(),
+      { width: window.innerWidth, height: window.innerHeight },
+    );
+    position.value = { left: `${point.left}px`, top: `${point.top}px` };
+  }
+
+  function scheduleHide() {
+    cancelHide();
+    timer = setTimeout(() => {
+      if (document.activeElement !== trigger.value) hide();
+    }, 140);
+  }
+
+  function toggle() {
+    if (visible.value) hide();
+    else show();
+  }
+
+  function dismissOnEscape(event) {
+    if (event.key === "Escape") hide();
+  }
+
+  function dismissOutside(event) {
+    if (!trigger.value?.contains(event.target) && !tooltip.value?.contains(event.target)) hide();
+  }
+
+  function dismissOnScroll(event) {
+    if (!tooltip.value?.contains(event.target)) hide();
+  }
+
+  onMounted(() => {
+    document.addEventListener("keydown", dismissOnEscape);
+    document.addEventListener("pointerdown", dismissOutside);
+    window.addEventListener("resize", hide);
+    window.addEventListener("scroll", dismissOnScroll, true);
+  });
+
+  onBeforeUnmount(() => {
+    hide();
+    document.removeEventListener("keydown", dismissOnEscape);
+    document.removeEventListener("pointerdown", dismissOutside);
+    window.removeEventListener("resize", hide);
+    window.removeEventListener("scroll", dismissOnScroll, true);
+  });
+
+  return {
+    trigger, tooltip, tooltipId, visible, position,
+    show, hide, scheduleHide, cancelHide, toggle,
+  };
+}
diff --git a/frontend/src/views/components/HelpTip/HelpTip.test.js b/frontend/src/views/components/HelpTip/HelpTip.test.js
new file mode 100644
index 0000000..0b5b35a
--- /dev/null
+++ b/frontend/src/views/components/HelpTip/HelpTip.test.js
@@ -0,0 +1,108 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { placeTooltip } from "./HelpTipPosition.js";
+import { useHelpTip } from "./HelpTip.js";
+import { mountComposable } from "../../../test-support/mount.js";
+
+const viewport = { width: 1366, height: 768 };
+const popup = { width: 340, height: 70 };
+
+test("tooltip stays below the trigger when space is available", () => {
+  assert.deepEqual(placeTooltip({ left: 100, top: 100, bottom: 117 }, popup, viewport), {
+    left: 100, top: 125,
+  });
+});
+
+test("tooltip flips above the trigger near the bottom edge", () => {
+  assert.deepEqual(placeTooltip({ left: 100, top: 720, bottom: 737 }, popup, viewport), {
+    left: 100, top: 642,
+  });
+});
+
+test("tooltip clamps at both horizontal edges", () => {
+  assert.equal(placeTooltip({ left: 1320, top: 100, bottom: 117 }, popup, viewport).left, 1014);
+  assert.equal(placeTooltip({ left: -10, top: 100, bottom: 117 }, popup, viewport).left, 12);
+});
+
+test("tooltip handles a viewport smaller than its measured content", () => {
+  assert.deepEqual(placeTooltip({ left: 0, top: 0, bottom: 17 }, popup, { width: 100, height: 50 }), {
+    left: 12, top: 12,
+  });
+});
+
+async function setup(t) {
+  const events = new Map();
+  function addEventListener(name, callback) {
+    events.set(name, callback);
+  }
+  function removeEventListener(name, callback) {
+    assert.equal(events.get(name), callback);
+    events.delete(name);
+  }
+  const mounted = await mountComposable(t, () => {
+    Object.assign(window, { ...viewport, innerWidth: viewport.width, innerHeight: viewport.height, addEventListener, removeEventListener });
+    Object.assign(document, { activeElement: null, addEventListener, removeEventListener });
+    return useHelpTip();
+  });
+  mounted.state.trigger.value = {
+    getBoundingClientRect: () => ({ left: 100, top: 100, bottom: 117 }),
+    contains: () => false,
+  };
+  mounted.state.tooltip.value = {
+    getBoundingClientRect: () => popup,
+    contains: () => false,
+  };
+  return { ...mounted, events };
+}
+
+test("tooltip opens, positions and closes on Escape", async (t) => {
+  const { state, events } = await setup(t);
+  assert.equal(state.visible.value, false);
+  await state.show();
+  assert.equal(state.visible.value, true);
+  assert.deepEqual(state.position.value, { left: "100px", top: "125px" });
+  events.get("keydown")({ key: "Escape" });
+  assert.equal(state.visible.value, false);
+});
+
+test("tooltip can be reached by pointer without closing", async (t) => {
+  const { state } = await setup(t);
+  await state.show();
+  state.scheduleHide();
+  state.cancelHide();
+  await new Promise(resolve => setTimeout(resolve, 180));
+  assert.equal(state.visible.value, true);
+  state.scheduleHide();
+  await new Promise(resolve => setTimeout(resolve, 180));
+  assert.equal(state.visible.value, false);
+});
+
+test("focused tooltip remains open on pointer leave", async (t) => {
+  const { state } = await setup(t);
+  document.activeElement = state.trigger.value;
+  await state.show();
+  state.scheduleHide();
+  await new Promise(resolve => setTimeout(resolve, 180));
+  assert.equal(state.visible.value, true);
+  state.hide();
+  assert.equal(state.visible.value, false);
+});
+
+test("outside click and viewport changes dismiss the tooltip", async (t) => {
+  const { state, events } = await setup(t);
+  for (const event of ["pointerdown", "resize", "scroll"]) {
+    await state.show();
+    events.get(event)({ target: {} });
+    assert.equal(state.visible.value, false);
+  }
+});
+
+test("unmount cancels pending work and removes all event listeners", async (t) => {
+  const { state, events, unmount } = await setup(t);
+  const pending = state.show();
+  state.scheduleHide();
+  unmount();
+  await pending;
+  assert.equal(state.visible.value, false);
+  assert.equal(events.size, 0);
+});
diff --git a/frontend/src/views/components/HelpTip/HelpTip.vue b/frontend/src/views/components/HelpTip/HelpTip.vue
new file mode 100644
index 0000000..ff273c1
--- /dev/null
+++ b/frontend/src/views/components/HelpTip/HelpTip.vue
@@ -0,0 +1,53 @@
+<script setup>
+import { useHelpTip } from "./HelpTip.js";
+
+const {
+  trigger,
+  tooltip,
+  tooltipId,
+  visible,
+  position,
+  show,
+  hide,
+  scheduleHide,
+  cancelHide,
+  toggle,
+} = useHelpTip();
+</script>
+
+<template>
+  <span
+    ref="trigger"
+    class="help-tip-trigger"
+    role="button"
+    tabindex="0"
+    :aria-labelledby="tooltipId"
+    :aria-expanded="visible"
+    @pointerenter="show"
+    @pointerleave="scheduleHide"
+    @focus="show"
+    @blur="hide"
+    @click.stop.prevent="toggle"
+    @keydown.enter.stop.prevent="toggle"
+    @keydown.space.stop.prevent="toggle"
+    @keydown.esc.stop.prevent="hide"
+  >
+    <span aria-hidden="true">?</span>
+  </span>
+  <Teleport to="body">
+    <span
+      v-show="visible"
+      :id="tooltipId"
+      ref="tooltip"
+      class="help-tip-content"
+      role="tooltip"
+      :style="position"
+      @pointerenter="cancelHide"
+      @pointerleave="scheduleHide"
+    >
+      <slot />
+    </span>
+  </Teleport>
+</template>
+
+<style scoped src="./HelpTip.css"></style>
diff --git a/frontend/src/views/components/HelpTip/HelpTipPosition.js b/frontend/src/views/components/HelpTip/HelpTipPosition.js
new file mode 100644
index 0000000..2db0a87
--- /dev/null
+++ b/frontend/src/views/components/HelpTip/HelpTipPosition.js
@@ -0,0 +1,14 @@
+export function placeTooltip(anchor, popup, viewport) {
+  const padding = 12;
+  const gap = 8;
+  const maxLeft = Math.max(padding, viewport.width - popup.width - padding);
+  const left = Math.max(padding, Math.min(anchor.left, maxLeft));
+  const below = anchor.bottom + gap;
+  const above = anchor.top - popup.height - gap;
+  const preferred = below + popup.height <= viewport.height - padding ? below : above;
+  const maxTop = Math.max(padding, viewport.height - popup.height - padding);
+  return {
+    left,
+    top: Math.max(padding, Math.min(preferred, maxTop)),
+  };
+}