查看布局的技巧

javascript: (function(){
    var style = document.querySelector('#_outline_');
    if (style) {
        style.parentNode.removeChild(style);
    } else {
        style = document.createElement('style');
        style.id = '_outline_';
        style.innerHTML = "*{outline: 1px solid red}";
        document.body.appendChild(style);
    }
})();