Standart CSS to reset standart (default) browser styles to use custom styles and it will work properly. Сброс стандартных стилей браузеров.

css_reset.css

html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed, figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary, time, mark, audio, video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
  outline: none;
}
html { height: 101%; } /* always display scrollbars */
body { font-size: 62.5%; line-height: 1; font-family: Arial, Tahoma, Verdana, sans-serif; }

article, aside, details, figcaption, figure, footer, header, hgroup, menu, nav, section { display: block; }
ol, ul { list-style: none; }

blockquote, q { quotes: none; }
blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; }
strong { font-weight: bold; } 

input { outline: none; }

table { border-collapse: collapse; border-spacing: 0; }
img { border: 0; max-width: 100%; }

a { text-decoration: none; }
a:hover { text-decoration: underline; }