Replace rebass with own Modal component

src/components/modals/Overlay.jsx

@@ -0,0 +1,53 @@
+import React from 'react'
+
+class ViewportOverlay extends React.Component {
+  static propTypes = {
+    style: React.PropTypes.object
+  }
+
+  render() {
+    const overlayStyle = {
+      position: 'fixed',
+      top: 0,
+      right: 0,
+      bottom: 0,
+      left: 0,
+      zIndex: 2,
+      opacity: 0.875,
+      backgroundColor: 'rgb(28, 31, 36)',
+      ...this.props.style
+    }
+
+    return <div style={overlayStyle} />
+  }
+}
+
+class Overlay extends React.Component {
+  static propTypes = {
+    isOpen: React.PropTypes.bool.isRequired,
+    children: React.PropTypes.element.isRequired
+  }
+
+  render() {
+    return <div style={{
+      top: 0,
+      right: 0,
+      bottom: 0,
+      left: 0,
+      position: 'fixed',
+      display: this.props.isOpen ? 'flex' : 'none',
+      flexDirection: 'column',
+      alignItems: 'center',
+      justifyContent: 'center'
+    }}>
+      <ViewportOverlay />
+      <div style={{
+        zIndex: 3,
+      }}>
+      {this.props.children}
+      </div>
+    </div>
+  }
+}
+
+export default Overlay