🪄 Implement LivePreview support

closes #1

Package.swift

@@ -10,7 +10,7 @@ let package = Package(
         .library(name: "Autolayout", type: .static, targets: ["Autolayout"])
     ],
     dependencies: [
-        .package(url: "https://github.com/swifweb/web", from: "1.0.0-beta.1.22.0")
+        .package(url: "https://github.com/swifweb/web", from: "1.0.0-beta.1.22.2")
     ],
     targets: [
         .target(name: "Autolayout", dependencies: [

README.md

@@ -23,7 +23,7 @@ Add package to your SwifWeb app's `Package.swift`
 In dependencies section
 ```swift
  dependencies: [
-    .package(url: "https://github.com/swifweb/autolayout", from: "1.0.0")
+    .package(url: "https://github.com/swifweb/autolayout", from: "1.0.1")
 ]
 ```
 In target section
@@ -778,3 +778,40 @@ Sets the opacity level for an element
 // will set opacity to 0.5 only for extra-small, small and medium screens
 .opacity(0.5, breakpoints: .xs, .s, m)
 ```
+
+# Live preview
+
+To make it work with live preview you need to specify either all styles or exact autolayout's one
+
+#### With all app styles included
+```swift
+class Welcome_Preview: WebPreview {
+    override class var title: String { "Initial page" } // optional
+    override class var width: UInt { 440 } // optional
+    override class var height: UInt { 480 } // optional
+
+    @Preview override class var content: Preview.Content {
+        // add styles if needed
+        AppStyles.all
+        // add here as many elements as needed
+        WelcomeViewController()
+    }
+}
+```
+
+#### With exact app styles including autoalyout's one
+```swift
+class Welcome_Preview: WebPreview {
+    override class var title: String { "Initial page" } // optional
+    override class var width: UInt { 440 } // optional
+    override class var height: UInt { 480 } // optional
+
+    @Preview override class var content: Preview.Content {
+        // add styles if needed
+        AppStyles.id(.mainStyle)
+        AppStyles.id(.autolayoutStyles)
+        // add here as many elements as needed
+        WelcomeViewController()
+    }
+}
+```'

Sources/Autolayout/Autolayout.swift

@@ -10,11 +10,18 @@ import ResizeObserverAPI
 
 let _autolayout = Autolayout()
 
+extension Id {
+    public static var autolayoutStyles: Id { "autolayout_styles" }
+}
+
 public class Autolayout {
-    let stylesheet = Stylesheet().id("autolayout_styles")
+    let stylesheet = Stylesheet().id(.autolayoutStyles)
     var ruleIndexCache: [String: Int] = [:]
 
     fileprivate init () {
+        #if WEBPREVIEW
+        WebApp.shared.stylesheets.append(stylesheet)
+        #endif
         WebApp.shared.document.head.appendChild(stylesheet)
     }