siyuan/app/src/assets/scss/component/_button.scss

.b3-button {
  cursor: pointer;
  color: var(--b3-theme-on-primary);
  border-radius: var(--b3-border-radius);
  line-height: 20px;
  padding: 4px 8px;
  background-color: var(--b3-theme-primary);
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: box-shadow 280ms cubic-bezier(0.4, 0, 0.2, 1);
  border: 0;
  box-sizing: border-box;
  text-align: center;

  svg {
    height: 16px;
    width: 16px;
    margin-right: 4px;
    flex-shrink: 0;
  }

  &:hover,
  &:focus,
  &--progress {
    text-decoration: none;
    box-shadow: var(--b3-button-shadow);
  }

  &:active {
    box-shadow: 0px 5px 5px -3px rgba(0, 0, 0, 0.2), 0px 8px 10px 1px rgba(0, 0, 0, 0.14), 0px 3px 14px 2px rgba(0, 0, 0, .12);
  }

  &--progress {
    position: relative;
    background-color: transparent;
    height: 28px;

    & > span {
      position: absolute;
      content: " ";
      height: 100%;
      left: 0;
      top: 0;
      width: 50%;
      background-color: var(--b3-theme-primary);
      border-radius: var(--b3-border-radius);
    }
  }

  &--small {
    padding: 0 4px;
    font-size: 12px;
  }

  &--mid {
    padding: 2px 8px;
  }

  &--big {
    min-width: 214px;
    background: var(--b3-theme-secondary);
    color:var(--b3-theme-on-secondary);
    padding: 24px 16px;
    font-size: 16px;
  }

  &--text,
  &--cancel {
    color: var(--b3-theme-primary);
    background-color: transparent;

    &:hover,
    &:focus {
      background-color: var(--b3-theme-primary-lightest);
      box-shadow: none;
    }

    &:active {
      background-color: var(--b3-theme-primary-lighter);
      box-shadow: none;
    }
  }

  &--cancel {
    color: var(--b3-theme-on-surface);
  }

  &--outline {
    color: var(--b3-theme-primary);
    box-shadow: inset 0 0 0 .6px var(--b3-theme-primary);
    background-color: transparent;

    &:hover,
    &:focus {
      background-color: var(--b3-theme-primary-lightest);
      box-shadow: inset 0 0 0 1px var(--b3-theme-primary);
    }

    &:active {
      background-color: var(--b3-theme-primary-lighter);
      box-shadow: inset 0 0 0 1px var(--b3-theme-primary);
    }
  }

  &--white {
    padding: 4px 8px;
    font-size: 12px;
    background-color: #fafbfc;
    color: var(--b3-theme-primary);

    &:hover,
    &:focus {
      background-color: #f3f4f6;
    }
  }

  &--error {
    color: var(--b3-card-error-color);
    background-color: var(--b3-card-error-background);
  }

  &--warning {
    color: var(--b3-card-warning-color);
    background-color: var(--b3-card-warning-background);
  }

  &--info {
    color: var(--b3-card-info-color);
    background-color: var(--b3-card-info-background);
  }

  &--success {
    color: var(--b3-card-success-color);
    background-color: var(--b3-card-success-background);
  }

  &:disabled {
    opacity: 0.38;
    cursor: not-allowed;
  }
}