bulma/sass/form/input-textarea.scss

$textarea-padding: $control-padding-horizontal !default;
$textarea-max-height: 40em !default;
$textarea-min-height: 8em !default;

$textarea-colors: $form-colors !default;

%input-textarea {
  @extend %input;

  box-shadow: $input-shadow;
  max-width: 100%;
  width: 100%;

  &[readonly] {
    box-shadow: none;
  }

  // Colors
  @each $name, $pair in $textarea-colors {
    $color: nth($pair, 1);

    &.is-#{$name} {
      border-color: $color;

      &:focus,
      &.is-focused,
      &:active,
      &.is-active {
        box-shadow: $input-focus-box-shadow-size bulmaRgba($color, 0.25);
      }
    }
  }

  // Sizes
  &.is-small {
    @include control-small;
  }

  &.is-medium {
    @include control-medium;
  }

  &.is-large {
    @include control-large;
  }

  // Modifiers
  &.is-fullwidth {
    display: block;
    width: 100%;
  }

  &.is-inline {
    display: inline;
    width: auto;
  }
}

.#{$class-prefix}input {
  @extend %input-textarea;

  &.is-rounded {
    border-radius: $radius-rounded;
    padding-left: calc(#{$control-padding-horizontal} + 0.375em);
    padding-right: calc(#{$control-padding-horizontal} + 0.375em);
  }

  &.is-static {
    background-color: transparent;
    border-color: transparent;
    box-shadow: none;
    padding-left: 0;
    padding-right: 0;
  }
}

.#{$class-prefix}textarea {
  @extend %input-textarea;

  display: block;
  max-width: 100%;
  min-width: 100%;
  padding: $textarea-padding;
  resize: vertical;

  &:not([rows]) {
    max-height: $textarea-max-height;
    min-height: $textarea-min-height;
  }

  &[rows] {
    height: initial;
  }

  // Modifiers
  &.has-fixed-size {
    resize: none;
  }
}