Styling issues for OAS 3.1 and Swagger 2.x API documentations

Q&A (please complete the following information)

• OS: [e.g. macOS] Windows 11
• Browser: [e.g. chrome, safari] Chrome
• Version: [e.g. 22] 122
• Method of installation: [e.g. npm, dist assets] npm
• Swagger-UI version: 5.11.10, 5.12.0
• Swagger/OpenAPI version: Swagger 2.0 and/ or OpenAPI 3.1

Content & configuration

Example Swagger/OpenAPI definition:

{
  "openapi": "3.1.0",
  "info": {
    "version": "1.0.0",
    "title": "Swagger Petstore",
    "license": {
      "name": "MIT",
      "url": "https://opensource.org/licenses/MIT"
    }
  },
  "servers": [
    {
      "url": "http://petstore.swagger.io/v1"
    }
  ],
  "paths": {
    "/pets": {
      "get": {
        "summary": "List all pets",
        "operationId": "listPets",
        "tags": [
          "pets"
        ],
        "parameters": [
          {
            "name": "limit",
            "in": "query",
            "description": "How many items to return at one time (max 100)",
            "required": false,
            "schema": {
              "type": "integer",
              "format": "int32"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "A paged array of pets",
            "headers": {
              "x-next": {
                "description": "A link to the next page of responses",
                "schema": {
                  "type": "string"
                }
              }
            },
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Pets"
                }
              }
            }
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      },
      "post": {
        "summary": "Create a pet",
        "operationId": "createPets",
        "tags": [
          "pets"
        ],
        "responses": {
          "201": {
            "description": "Null response"
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    },
    "/pets/{petId}": {
      "get": {
        "summary": "Info for a specific pet",
        "operationId": "showPetById",
        "tags": [
          "pets"
        ],
        "parameters": [
          {
            "name": "petId",
            "in": "path",
            "required": true,
            "description": "The id of the pet to retrieve",
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Expected response to a valid request",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Pet"
                }
              }
            }
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Pet": {
        "type": "object",
        "required": [
          "id",
          "name"
        ],
        "properties": {
          "id": {
            "type": "integer",
            "format": "int64"
          },
          "name": {
            "type": "string"
          },
          "tag": {
            "type": "string"
          }
        }
      },
      "Pets": {
        "type": "array",
        "items": {
          "$ref": "#/components/schemas/Pet"
        }
      },
      "Error": {
        "type": "object",
        "required": [
          "code",
          "message"
        ],
        "properties": {
          "code": {
            "type": "integer",
            "format": "int32"
          },
          "message": {
            "type": "string"
          }
        }
      }
    }
  }
}

Swagger-UI configuration options:

SwaggerUI({
        spec: apiSpec,
        defaultModelsExpandDepth: -1,
        dom_id: '#container',
        defaultModelRendering: 'model',
        showExtensions: true,
        deepLinking: true
})

Describe the bug you're encountering

There are styling issues for OAS 3.1 and Swagger 2.x API documentations as seen in below sceenshot.

Expected behavior

Consistent and clean UI

Screenshots

Start by reproducing the styling problem with the supplied OpenAPI 3.1 example and Swagger UI configuration in Chrome using Swagger UI 5.11.10 or 5.12.0. Compare the rendered documentation for OpenAPI 3.1 and Swagger 2.x against the screenshot; done means the affected views have a consistent, clean appearance.