Space Themed Spacechan Theme (no curved boxes)

body {
background: url("https://i.imgur.com/N5yFPgq.png");
}
nav {
background-image: linear-gradient(to left, aqua , black, black);
border-bottom: 1px solid #4169E1;
}
.coloredIcon {
color: #216db9;
}
.catalogCell {
background: #040404;
border: 1px solid #4169E1;
border-radius: 0px;
}
input, select, textarea {
border: 1px double #4169E1;
background: #040404;
border-radius: 0px;
}
input[type=button], input[type=submit], button, .dropzone, .selectedCell
{
border: 3px double #4169E1;
background: #040404;
border-radius: 0px;
}
#postingForm th {
border: 1px solid #4169E1;
background: #040404;
border-radius: 0px;
}
.innerPost, .markedPost {
background: #040404;
border: 1px solid #4169E1;
border-radius: 0px;
}
#newPostFieldset, #quick-reply table, .modalDecorationPanel {
border: 1px dashed #00D4FF;
}
hr {
border-color: #00D4FF;
}
.reportFieldset {
border: 1px dashed #00D4FF;
}
.noEmailName, .noEmailName:hover {
color: #98E;
}
a {
color: #216db9;
}
.sideCatalogCell, .sideCatalogMarkedCell {
background: #040404;
border: 1px solid #4169E1;
border-radius: 0px;
}
#divLatestPosts .latestPostCell {
background: #040404;
border: 1px solid #4169E1;
border-radius: 0px;
}
span.spoiler {
  background: teal;
  color: teal;
  padding: 0 1px;
}
.redText {
  /*  background-image: repeating-linear-gradient(90deg, violet, indigo, blue, green, yellow, orange, red, violet); */
    background-image: repeating-linear-gradient(90deg, red, orange, yellow, green, blue, indigo, violet, red);
/*  background-image: repeating-linear-gradient(90deg, #E40303, #FF8C00, #FFED00, #008026, #004DFF, #750787, #E40303); */
    background-size: 50% 100%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: rainbow 1s linear infinite;
    font-size: 1.5em;
    text-transform: uppercase;
}

@keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-webkit-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-moz-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-ms-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}
.floatingMenu {
  border: 1px dashed #00D4FF;
  background: #1d1f21;
  padding: 0.25em;
}
input[type=checkbox].postingCheckbox+label:before {
    color: aqua;
}
a.rules:after {
color: #117743;
}
    header {
         /*  background-image: repeating-linear-gradient(90deg, violet, indigo, blue, green, yellow, orange, red, violet); */
    background-image: repeating-linear-gradient(90deg, red, orange, yellow, green, blue, indigo, violet, red);
/*  background-image: repeating-linear-gradient(90deg, #E40303, #FF8C00, #FFED00, #008026, #004DFF, #750787, #E40303); */
    background-size: 50% 100%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: rainbow 1s linear infinite;
    font-size: normal;
    text-transform: uppercase;
}

@keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-webkit-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-moz-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
}

@-ms-keyframes rainbow {
    0%{background-position:0% 50%}
    100%{background-position:100% 50%}
    }