angular/adev/shared-docs/styles/_button.scss

@mixin button() {
  button {
    font-family: var(--inter-font);
    background: transparent;
    -webkit-appearance: none;
    border: 0;
    font-weight: 600;

    // Remove excess padding and border in Firefox 4+
    &::-moz-focus-inner {
      border: 0;
      padding: 0;
    }

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

  @property --angle {
    syntax: '<angle>';
    initial-value: 90deg;
    inherits: false;
  }

  @keyframes spin-gradient {
    0% {
      --angle: 90deg;
    }
    100% {
      --angle: 450deg;
    }
  }

  .docs-primary-btn {
    cursor: pointer;
    border: none;
    outline: none;
    position: relative;
    border-radius: 0.25rem;
    padding: 0.75rem 1.5rem;
    width: max-content;
    color: transparent;
    user-select: none;

    // border gradient / background
    --angle: 90deg;
    background: linear-gradient(
      var(--angle),
      var(--orange-red) 0%,
      var(--vivid-pink) 50%,
      var(--electric-violet) 100%
    );

    docs-icon {
      z-index: var(--z-index-content);
      position: relative;
    }

    // text & radial gradient
    &::before {
      content: attr(text);
      position: absolute;
      inset: 1px;
      background: var(--page-bg-radial-gradient);
      border-radius: 0.2rem;
      display: flex;
      align-items: center;
      justify-content: center;
      transition:
        opacity 0.3s ease,
        background 0.3s ease;
      color: var(--primary-contrast);
    }

    // solid color negative space - CSS transition supported
    &::after {
      content: attr(text);
      position: absolute;
      inset: 1px;
      background: var(--page-background);
      border-radius: 0.2rem;
      display: flex;
      align-items: center;
      justify-content: center;
      transition:
        opacity 0.3s ease,
        background 0.3s ease;
      color: var(--primary-contrast);
    }

    &:hover {
      animation: spin-gradient 4s linear infinite forwards;
      &::before {
        background-color: var(--page-background);
        background: var(--soft-pink-radial-gradient);
        opacity: 0.9;
      }
      &::after {
        opacity: 0;
      }
    }

    &:active {
      &::before {
        opacity: 0.8;
      }
    }

    &:disabled {
      //gradient stroke
      background: var(--quinary-contrast);
      color: var(--quinary-contrast);

      &::before {
        background-color: var(--page-background);
        background: var(--page-bg-radial-gradient);
        opacity: 1;
      }

      docs-icon {
        color: var(--quinary-contrast);
      }
    }

    docs-icon {
      z-index: var(--z-index-icon);
      color: var(--primary-contrast);
    }
  }

  .docs-secondary-btn {
    border: 1px solid var(--senary-contrast);
    background: var(--page-background);
    padding: 0.75rem 1.5rem;
    border-radius: 0.25rem;
    color: var(--primary-contrast);
    transition: background 0.3s ease;

    docs-icon {
      color: var(--quaternary-contrast);
      transition: color 0.3s ease;
    }

    &:hover {
      background: var(--septenary-contrast);

      docs-icon {
        color: var(--primary-contrast);
      }
    }
  }
}