A dark mode for your tabs.

/* set up your colors, if developing a custom theme these should be set globally for your entire theme */
:root {
--color-bg1: #010412;
--color-g1: #1b2152;
--color-g2: #090d21;
--color-tab-text1: #c2c6ee;
--color-text1: #fff;
--color-tab-border: transparent;
}
/* set background gradient for content area including active tab */
#app .blocks-tabs .block-card {
background: linear-gradient(135deg, var(--color-g1) 0%, var(--color-g2) 100%);
}
/* add top border color for active tab, this uses the theme color variable */
#app .blocks-tabs__header-item--active {
border-top: 2px solid var(--color-theme);
}
#app .blocks-tabs__content { border-color:var(--color-tab-border); transition:.5s ease-out all; padding-top: 1em;}
#app .blocks-tabs__header-item { border-color:var(--color-tab-border);}
#app .blocks-tabs__header-item:not(.blocks-tabs__header-item--active ) {
background: var(--color-bg1);
}
#app .blocks-tabs__content-item {
padding: 2rem 3rem;
}
#app .blocks-tabs .brand--linkColor {
color: var(--color-tab-text1);
}
#app .blocks-tabs__content p{
color:var(--color-text1);
margin-bottom:1em;
}
/* mobile indicator for offcanvas tabs */
#app .blocks-tabs__controls::after {
background: linear-gradient(to left,rgba(1,1,1,.9),rgba(1,1,1,.01));
border-right: 1px solid #000;
}
#app .blocks-tabs__controls::before {
background: linear-gradient(to right,rgba(1,1,1,.9),rgba(1,1,1,.01));
border-left: 1px solid #000;
}