style.css

html {
  margin: 0;
  padding: 0;
}

body {
  font: 14px/20px Arial, sans-serif;
  height: auto;
  margin: 10px;
  overflow: hidden;
  width: 480px;
  user-select: none;
}

label {
  display: inline-block;
  padding: 5px 0;
}

input, select, textarea {
  border: none;
  border-bottom-width: 1px;
  border-bottom-style: dotted;
  border-radius: 2px;
  padding: 2px;
}

.paragraphs-label {
  width: 150px;
}

.words-label {
  width: 200px;
}

.add-tags-label {
  width: 120px;
}

#paragraphs-input, #words-input {
  text-align: center;
  width: 40px;
}

#copy-button {
  border-width: 1px;
  border-style: solid;
  margin-top: 5px;
  margin-bottom: 0;
  padding: 5px 12px;
  width: 480px;
}

#copy-button[disabled] {
  box-shadow: none;
}

#lipsum-textarea {
  border: none;
  height: 300px;
  margin-top: 10px;
  overflow-x: hidden;
  overflow-y: auto;
  padding: 10px;
  resize: none;
  width: 460px;
  border-radius: 5px;
}

#autocopy-delay {
  width: 50px
}

.checkbox-container {
  position: relative;
  padding-left: 24px;
  margin-bottom: 0px;
  user-select: none;
  box-sizing: border-box;
}

.checkbox-container input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
  height: 0;
  width: 0;
  margin: 0;
}

.checkmark {
  position: absolute;
  top: 7px;
  left: 4px;
  height: 12px;
  width: 12px;
  background-color: rgb(var(--control-background-rgb));
  box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.1);
  border-width: 1px;
  border-style: solid;
  border-radius: 2px;
}

.checkbox-container:hover input ~ .checkmark {
  border-width: 1px;
  border-style: solid;
}

.checkbox-container input:checked ~ .checkmark {
  border-color: transparent;
}

.checkmark:after {
  content: '';
  position: absolute;
  display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
  display: block;
}

.checkbox-container .checkmark:after {
  left: 4px;
  top: 0px;
  width: 3px;
  height: 8px;
  border-style: solid;
  border-width: 0 2px 2px 0;
  transform: rotate(40deg) skew(0deg, 8deg);
}

.option-field {
  min-height: 30px;
  display: block;
}


/* --- Theme --- */

:root {
  --black-rgb: 20 21 25;
  --white-rgb: 235 235 235;
}

@media (prefers-color-scheme: light) {
  :root {
      --background-rgb: var(--white-rgb);
      --background-inverse-rgb: var(--black-rgb);
      --control-background-rgb: var(--black-rgb) / 10%;
      --text-rgb: var(--black-rgb) / 80%;
  }
}
@media (prefers-color-scheme: dark) {
  :root {
      --background-rgb: var(--black-rgb);
      --background-inverse-rgb: var(--white-rgb);
      --control-background-rgb: var(--white-rgb) / 10%;
      --text-rgb: var(--white-rgb) / 80%;
  }
}

:root.theme-light {
  --background-rgb: var(--white-rgb);
  --background-inverse-rgb: var(--black-rgb);
  --control-background-rgb: var(--black-rgb) / 10%;
  --text-rgb: var(--black-rgb) / 80%;
}

:root.theme-dark {
  --background-rgb: var(--black-rgb);
  --background-inverse-rgb: var(--white-rgb);
  --control-background-rgb: var(--white-rgb) / 10%;
  --text-rgb: var(--white-rgb) / 80%;
}

input, select, textarea {
  background-color: rgb(var(--control-background-rgb));
  color: rgb(var(--text-rgb));
  box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.1);
}

input:hover, select:hover, textarea:hover {
  box-shadow: inset 0px 1px 3px rgba(0, 0, 0, 0.3);
}

input:focus, select:focus, textarea:focus {
  outline: rgb(var(--background-inverse-rgb) / 80%) solid 1px;
}

body {
  background-color: rgb(var(--background-rgb));
  color: rgb(var(--text-rgb));
}

#paragraphs-input, #words-input {
  border-bottom-color: rgb(var(--background-inverse-rgb) / 20%);
}

#copy-button {
  background-color: rgb(var(--background-inverse-rgb) / 15%);
  border-color: rgb(var(--background-inverse-rgb) / 20%);
  color: rgb(var(--text-rgb));
  box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.1);
}

#copy-button:hover {
  background-color: rgb(var(--background-inverse-rgb) / 10%);
  border-color: rgb(var(--background-inverse-rgb) / 15%);
  color: rgb(var(--text-rgb));
  box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.2);
}

#copy-button:active {
  background-color: rgb(var(--background-inverse-rgb) / 5%);
  border-color: rgb(var(--background-inverse-rgb) / 10%);
  box-shadow: inset 0px 1px 3px rgba(0, 0, 0, 0.2);
}

#copy-button[disabled] {
  background-color: rgb(var(--background-inverse-rgb) / 5%);
  border-color: rgb(var(--background-inverse-rgb) / 10%);
  color: #888;
  box-shadow: none;
}

input:invalid {
  border-bottom: 1px dotted red !important;
}

.checkmark {
  position: absolute;
  top: 7px;
  left: 4px;
  height: 12px;
  width: 12px;
  background-color: rgb(var(--control-background-rgb));
  box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.1);
  border-color: rgb(var(--background-inverse-rgb) / 10%);
}

.checkbox-container:hover input ~ .checkmark {
  box-shadow: inset 0px 1px 3px rgba(0, 0, 0, 0.2);
  border-color: rgb(var(--background-inverse-rgb) / 20%);
}

.checkbox-container input:checked ~ .checkmark {
  border-color: transparent;
}

.checkbox-container input:focus ~ .checkmark {
  outline: rgb(var(--background-inverse-rgb) / 80%) solid 1px;
}

.checkbox-container .checkmark:after {
  border-color: rgb(var(--text-rgb));
}