* {
      box-sizing: border-box;
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
      margin: 0;
      padding: 0;
}

body, html {
        background-image: url('/admin/system/img/png/bg-1.png');
        background-position: center center;
        background-repeat: repeat;
        background-size: auto;
        min-width: 100vw;
        min-height: 100vh;
        max-width: 100vw;
        max-height: 100vh;
        user-select: none;
        margin: 0;
        padding: 0;
        -webkit-user-select: none; /* Safari */
        -moz-user-select: none;    /* Firefox */
        -ms-user-select: none;     /* IE/Edge */
}
/* Стили для WebKit (Chrome, Edge, Safari) */
::-webkit-scrollbar {
    width: 5px;
}

/* Полоса скролла */
::-webkit-scrollbar-thumb {
    background: rgba(0,0,0, 0.9);
    border-radius: 5px;
}

/* Фон под полоской скролла */
::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
}
#preloader{
    display: flex;
    align-items: center;
    justify-content: center;
    background-image: url('/admin/system/img/gif/preloader.gif');
    background-position: center center;
    background-size: 25px 25px;
    background-repeat: no-repeat;
    width: 100%;
    height: 100%;
}

.box div {
  width: 100px;
  height: 100px;
}
    width: 100%;
    height: 100%;
    background: #FF0000;
}