simple-slot-template.html

<template>
    <style>
        :host {
            display: block;
            contain: content;
            border: 1px solid rgba(255, 0, 0, .8);
            background-color: rgba(255, 0, 0, .4);
            border-radius: 4px;
            box-shadow: 0 0 10px rgba(128, 100, 38, 0.34);
            font-family: sans-serif;
            font-size: 16px;
            max-width: 300px;
            padding: 12px 16px;
        }
    </style>
    <slot name="emoji"></slot>
    <slot name="message"></slot>
</template>