When I'm too lazy to set up Tailwind and PurgeCSS for a prototype or a small project, then this will do.

base.css

/* Handicraft reset */
*,
*::before,
*::after {
  box-sizing: inherit;
}
html {
  box-sizing: border-box;
}
body {
  min-height: 100vh;
}
body,
body * {
  margin: 0;
  padding: 0;
}
body,
button,
input,
textarea {
  font-family: -apple-system, system-ui, BlinkMacSystemFont, 'Segoe UI', Roboto, Ubuntu;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

ol,
ul {
  list-style: none;
}

/* Global styles */
:root {
  --brand: #223;
  --gray: #8c8c8c;
  --contrast: #475DE5;
}
h1 {
  font-size: 1.875rem;
  line-height: 2.25rem;
  color: var(--gray-80);
  font-weight: 700;
}

button {
  display: block;
  border: none;
  background: none;
  color: inherit;
  font-size: inherit;
}
button[disabled],
.cursor-disabled {
  cursor: not-allowed;
}
label,
button,
.cursor-pointer {
  cursor: pointer;
}
.break-all {
  word-break: break-all;
}
.break-word {
  word-break: break-word;
}

a {
  text-decoration: none;
  color: inherit;
}
.content-link {
  display: inline-block;
  color: var(--brand);
  font-weight: 500;
}
.content-link:hover {
  text-decoration: underline;
}

::placeholder {
  color: var(--gray);
}
::selection {
  background-color: var(--contrast);
  color: white;
}

.profile-image {
  border-radius: 50%;
  height: 2rem;
  width: 2rem;
}

.bg-none {
  background-color: transparent;
}
.border-top {
  border-top: 1px solid var(--gray);
}
.border-right {
  border-right: 1px solid var(--gray);
}
.border-bottom {
  border-bottom: 1px solid var(--gray);
}
.border-left {
  border-left: 1px solid var(--gray);
}
.color-white {
  color: white;
}
.color-contrast {
  color: var(--contrast);
}
.text-center {
  text-align: center;
}
.text-right {
  text-align: right;
}
.text-left {
  text-align: left;
}
.text-ellipsis {
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}
.text-uppercase {
  text-transform: uppercase;
}

.icon-xs {
  height: 0.7rem;
  width: 0.7rem;
}
.icon-s {
  height: 0.825rem;
  width: 0.825rem;
}
.icon-m {
  height: 1rem;
  width: 1rem;
}
.icon-l {
  height: 1.5rem;
  width: 1.5rem;
}
.icon--flipped-y {
  transform: rotateY(180deg);
}
.icon--flipped-x {
  transform: rotateX(180deg);
}
.icon--flipped {
  transform: rotate(180deg);
}
.icon--rotated-left {
  transform: rotate(-90deg);
}
.icon--rotated-right {
  transform: rotate(90deg);
}
.padded-s {
  padding: 0.5rem;
}
.padded-m {
  padding: 1rem;
}
.padded-l {
  padding: 1.5rem;
}
.padded-xl {
  padding: 2rem;
}
.padded-0 {
  padding: 0 !important;
}
.padded {
  padding: 1rem;
}

.anim-spin {
  animation: spin 2s ease-out infinite;
}
@keyframes spin {
  100% {
    transform: rotate(360deg);
  }
}

.anim-shake {
  animation: shake 0.85s cubic-bezier(0.36, 0.07, 0.19, 0.97) both;
}
@keyframes shake {
  10%,
  90% {
    transform: translate3d(-1px, 0, 0);
  }

  20%,
  80% {
    transform: translate3d(2px, 0, 0);
  }

  30%,
  50%,
  70% {
    transform: translate3d(-4px, 0, 0);
  }

  40%,
  60% {
    transform: translate3d(4px, 0, 0);
  }
}

.hidden-visually {
  pointer-events: none !important;
  position: fixed !important;
  opacity: 0 !important;
  top: -10vh;
}
@media screen and (min-width: 65.01rem) {
  .hidden-wide {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }
  .hidden-wide--shift {
    display: none;
  }
}
@media screen and (max-width: 65rem) {
  .hidden-medium {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }
  .hidden-medium--shift {
    display: none;
  }
}
@media screen and (max-width: 40rem) {
  .hidden-narrow {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }
  .hidden-narrow--shift {
    display: none;
  }
}

.weight-default {
  font-weight: 400;
}
.weight-m,
.weight-bold {
  font-weight: 500;
}
.weight-l,
.weight-bolder {
  font-weight: 700;
}
.font-s {
  font-size: 0.875rem;
}
.font-xs {
  font-size: 0.75rem;
}
.font-l {
  font-size: 1.25rem;
}

.intrinsic {
  position: relative;
  height: 0;
  padding-bottom: calc(100% / (var(--aspect-ratio)));
}
.intrinsic-content {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
}
.full-height {
  height: 100%;
}

.f-v-center {
  display: flex;
  align-items: center;
}
.f-h-center {
  display: flex;
  justify-content: center;
}
.f-center {
  display: flex;
  align-items: center;
  justify-content: center;
}
.f-space {
  display: flex;
  justify-content: space-between;
}
.f-start {
  display: flex;
  justify-content: flex-start;
}
.f-end {
  display: flex;
  justify-content: flex-end;
}
.f-row {
  display: flex;
  flex-direction: row;
}
.f-row-reverse {
  display: flex;
  flex-direction: row-reverse;
}
.f-col {
  display: flex;
  flex-direction: column;
}
.f-col-reverse {
  display: flex;
  flex-direction: column-reverse;
}
.f-grow {
  flex-grow: 1;
}

.d-inline-block {
  display: inline-block;
}

.d-inline-flex {
  display: inline-flex;
}

.m-right-xxs {
  margin-right: 0.25rem;
}
.m-right-xs {
  margin-right: 0.5rem;
}
.m-right-s {
  margin-right: 0.75rem;
}
.m-right-m {
  margin-right: 1.5rem;
}
.m-right-l {
  margin-right: 3rem;
}
.m-right-a {
  margin-right: auto;
}
.m-left-xxs {
  margin-left: 0.25rem;
}
.m-left-xs {
  margin-left: 0.5rem;
}
.m-left-s {
  margin-left: 0.75rem;
}
.m-left-m {
  margin-left: 1.5rem;
}
.m-left-a {
  margin-left: auto;
}
.m-top-xxs {
  margin-top: 0.25rem;
}
.m-top-xs {
  margin-top: 0.5rem;
}
.m-top-s {
  margin-top: 0.75rem;
}
.m-top-m {
  margin-top: 1.5rem;
}
.m-top-l {
  margin-top: 3rem;
}
.m-bottom-xxs {
  margin-bottom: 0.25rem;
}
.m-bottom-xs {
  margin-bottom: 0.5rem;
}
.m-bottom-s {
  margin-bottom: 0.75rem;
}
.m-bottom-m {
  margin-bottom: 1.5rem;
}
.m-bottom-l {
  margin-bottom: 3rem;
}
.m-a-l {
  margin: 3rem;
}
.m-a-s {
  margin: 1rem;
}
.m-a-m {
  margin: 1.5rem;
}
.m-x-l {
  margin-left: 3rem;
  margin-right: 3rem;
}
.m-x-m {
  margin-left: 1.5rem;
  margin-right: 1.5rem;
}
.m-x-s {
  margin-left: 1rem;
  margin-right: 1rem;
}
.m-x-xs {
  margin-left: 0.5rem;
  margin-right: 0.5rem;
}
.m-x-xxs {
  margin-left: 0.2rem;
  margin-right: 0.2rem;
}
.m-left-0 {
  margin-left: 0 !important;
}

.m-bottom-0 {
  margin-bottom: 0 !important;
}

/* Custom scrollbars */
:root {
  --scrollbar-size: 6px;
  --scrollbar-minlength: 24px;
  --scrollbar-track-color: transparent;
  --scrollbar-color: rgba(74, 85, 104, 0.3);
}

.scrollbar-test {
  overflow-y: auto;
}

* {
  scrollbar-width: thin;
  scrollbar-color: var(--scrollbar-color) var(--scrollbar-track-color);
}

.layout-scrollbar-obtrusive *::-webkit-scrollbar {
  height: var(--scrollbar-size);
  width: var(--scrollbar-size);
}

::-webkit-scrollbar-track {
  background-color: var(--scrollbar-track-color);
}

::-webkit-scrollbar-thumb {
  background-color: var(--scrollbar-color);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:vertical,
::-webkit-scrollbar-thumb:vertical {
  min-height: var(--scrollbar-minlength);
}

::-webkit-scrollbar-thumb:horizontal,
::-webkit-scrollbar-thumb:horizontal {
  min-width: var(--scrollbar-minlength);
}