Add base overlay component

src/components/globals/BaseOverlay.vue

@@ -0,0 +1,61 @@
+<template>
+  <div class="overlay">
+    <button type="button" class="close-button" @click="closeOverlay">x</button>
+    <h1>{{ title }}</h1>
+    <div class="overlay-inner">
+      <slot/>
+    </div>
+  </div>
+</template>
+
+<script lang="ts">
+import { Component, Prop, Vue } from 'vue-property-decorator'
+
+@Component({
+  inheritAttrs: false,
+})
+export default class BaseOverlay extends Vue {
+  @Prop()
+  public title?: string
+
+  public closeOverlay() {
+    this.$emit('close')
+  }
+}
+</script>
+
+<style scoped lang="postcss">
+.overlay {
+  position: absolute;
+  top: 50%;
+  transform: translateY(-50%);
+  background-color: var(--bg-color);
+  width: 100vw;
+  height: 100vh;
+}
+.overlay-inner {
+  margin: 1em;
+}
+.close-button {
+  position: fixed;
+  top: 0;
+  right: 0;
+
+  color: var(--color);
+  border: none;
+  background-color: transparent;
+
+  z-index: 100;
+
+  width: 50px;
+  height: 50px;
+
+  font-size: 1.8rem;
+}
+h1 {
+  top: 0;
+  line-height: 50px;
+  font-size: 1.5em;
+  margin: 0;
+}
+</style>