Código base para hacer un reboot file

ax_reboot.scss

*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    font-size: 16px;
    line-height: 1.2;
}
h1,
h2,
h3,
h4,
h5,
h6,
small {
    font-size: inherit;
    font-weight: inherit;
}
em,
strong,
b {
    font-style: normal;
    font-weight: normal;
}
a {
    text-decoration: none;
    &:hover {
        text-decoration: none;
    }
}
mark {
    background: transparent;
}
input {
    &:focus {
        outline: none;
        box-shadow: 0;
    }
    &::placeholder {
        opacity: 1;
    }
}
fieldset {
    border-width: 0;
}
button {
    background: transparent;
    border-width: 0;
    cursor: pointer;
    &:active {
        color: inherit;
    }
    &:focus {
        outline: none;
    }
    &:required {
        box-shadow: none;
    }
}
ul,
ol {
    list-style: none;
}
label,
svg,
video,
canvas,
audio,
iframe,
embed,
object {
    display: block;
}
table {
    border-collapse: collapse;
}
th {
    text-align: inherit;
}
//temporal
span {
    vertical-align: unset;
}
[hidden] {
    display: none !important;
}