修复用户管理组件缺失的弹窗与表单样式

frontend/src/views/UserManagement/UserManagement.css

@@ -96,6 +96,138 @@
 .user-modal {
   width: min(100%, 620px);
 }
+.eyebrow {
+  margin: 0 0 8px;
+  color: #687792;
+  font-size: 12px;
+  font-weight: 700;
+  letter-spacing: 0;
+}
+.primary-button,
+.secondary-button {
+  min-height: 42px;
+  padding: 10px 16px;
+  border: 1px solid #d5ddea;
+  border-radius: 8px;
+  background: #fff;
+  color: #32405a;
+  font: inherit;
+  font-size: 14px;
+  font-weight: 700;
+  cursor: pointer;
+}
+.primary-button {
+  border-color: #315aaa;
+  background: #315aaa;
+  color: #fff;
+}
+button:disabled {
+  cursor: wait;
+  opacity: 0.6;
+}
+.text-button {
+  min-height: 36px;
+  padding: 6px;
+  border: 0;
+  color: #315aaa;
+  background: transparent;
+  font: inherit;
+  cursor: pointer;
+}
+.danger-text,
+.form-error {
+  color: #9c3b3b;
+}
+.modal-backdrop {
+  position: fixed;
+  inset: 0;
+  z-index: 10;
+  display: grid;
+  place-items: center;
+  overflow-y: auto;
+  padding: 16px;
+  background: rgba(18, 31, 58, 0.52);
+}
+.user-modal {
+  box-sizing: border-box;
+  max-height: calc(100dvh - 32px);
+  overflow: auto;
+  padding: 24px;
+  border: 1px solid #b9cbe0;
+  border-radius: 8px;
+  background: #fff;
+  box-shadow: 0 20px 60px rgba(19, 38, 79, 0.25);
+}
+.modal-heading {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 16px;
+  margin-bottom: 20px;
+}
+.modal-heading h2 {
+  margin: 0;
+  font-size: 24px;
+  letter-spacing: 0;
+}
+.close-button {
+  flex: 0 0 34px;
+  width: 34px;
+  height: 34px;
+  border: 0;
+  border-radius: 8px;
+  color: #687792;
+  background: #f1f4f8;
+  font-size: 24px;
+  cursor: pointer;
+}
+.form-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 14px;
+}
+.field {
+  display: flex;
+  min-width: 0;
+  flex-direction: column;
+  gap: 8px;
+  margin-bottom: 17px;
+  color: #32405a;
+  font-size: 13px;
+  font-weight: 700;
+}
+.field small {
+  color: #687792;
+  font-size: 12px;
+  font-weight: 400;
+}
+.field input,
+.field select {
+  box-sizing: border-box;
+  width: 100%;
+  min-width: 0;
+  height: 42px;
+  padding: 10px 12px;
+  border: 1px solid #bdcde0;
+  border-radius: 8px;
+  color: #172033;
+  background: #fff;
+  font: inherit;
+  font-weight: 400;
+}
+.field input:focus-visible,
+.field select:focus-visible,
+button:focus-visible {
+  outline: 2px solid #315aaa;
+  outline-offset: 2px;
+}
+.modal-actions {
+  display: flex;
+  justify-content: flex-end;
+  flex-wrap: wrap;
+  gap: 10px;
+  margin-top: 20px;
+}
 @media (max-width: 720px) {
   .user-management-heading {
     align-items: stretch;
@@ -108,4 +240,13 @@
   .user-table td {
     padding: 11px 8px;
   }
-}
+}
+@media (max-width: 480px) {
+  .form-grid {
+    grid-template-columns: minmax(0, 1fr);
+    gap: 0;
+  }
+  .user-modal {
+    padding: 18px;
+  }
+}