how to remove blue border on focus in css code example

Example 1: css remove border input focus

textarea:focus, input:focus{
    outline: none;
}

Example 2: html remove border from textarea

textarea {
    border: none;
    background-color: transparent;
    resize: none;
    outline: none;
}

Example 3: css remove blue outline button

button {
  outline: none;
}

Example 4: how to remove border from selected button

outline: none;

Example 5: css remove button outline

button:focus {outline:0;}

Example 6: remove button outlines

<button class="btn shadow-none">Bootstrap (4.1) button without shadow</button>