add "welcome" page

src/components/welcome/WelcomeSlideWrapper/index.tsx

@@ -0,0 +1,31 @@
+import { FC, PropsWithChildren, useMemo } from 'react';
+
+import styles from './styles.module.scss';
+
+interface Props {
+  background?: string;
+  color?: string;
+}
+
+const WelcomeSlideWrapper: FC<PropsWithChildren<Props>> = ({
+  children,
+  color,
+  background = '',
+}) => {
+  const style = useMemo(
+    () =>
+      background || color
+        ? {
+            backgroundImage: background && `url(${background})`,
+            backgroundColor: color,
+          }
+        : undefined,
+    [background, color],
+  );
+  return (
+    <div className={styles.layout} style={style}>
+      {children}
+    </div>
+  );
+};
+export { WelcomeSlideWrapper };

src/components/welcome/WelcomeSlideWrapper/styles.module.scss

@@ -0,0 +1,9 @@
+@import 'src/styles/variables';
+
+.layout {
+  min-height: 100vh;
+  width: 100vw;
+  background-size: cover;
+  background-position: 50% 50%;
+  padding: $header_height 0;
+}