Минимальный CSS Reset

html {
  box-sizing: border-box;
  font-size: 16px;
}
*, *:before, *:after {
  box-sizing: inherit;
}
body, h1, h2, h3, h4, h5, h6, p, ol, ul {
  margin: 0;
  padding: 0;
  font-weight: normal;
}
ol, ul {
  list-style: none;
}
img {
  max-width: 100%;
  height: auto;
}