Custom CSS to make Miniflux v1.x look like v2 :)

v2.css

@import url("/assets/css/app.min.css");
:root {
  --font-family:system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
  --body-color:#333;
  --body-background:#fff;
  --hr-border-color:#ccc;
  --title-color:#333;
  --link-color:#3366CC;
  --link-focus-color:red;
  --link-hover-color:#333;
  --link-visited-color:purple;
  --header-list-border-color:#ddd;
  --header-link-color:#444;
  --header-link-focus-color:#888;
  --header-link-hover-color:#888;
  --header-active-link-color:#444;
  --page-header-title-color:#333;
  --page-header-title-border-color:#333;
  --logo-color:#000;
  --logo-hover-color-span:#000;
  --table-border-color:#ddd;
  --table-th-background:#fcfcfc;
  --table-th-color:#333;
  --table-tr-hover-background-color:#f9f9f9;
  --table-tr-hover-color:#333;
  --button-primary-border-color:#3079ed;
  --button-primary-background:#4d90fe;
  --button-primary-color:#fff;
  --button-primary-focus-border-color:#2f5bb7;
  --button-primary-focus-background:#357ae8;
  --input-border:1px solid #ccc;
  --input-background:#fff;
  --input-color:#333;
  --input-placeholder-color:#d0d0d0;
  --input-focus-color:#000;
  --input-focus-border-color:rgba(82, 168, 236, 0.8);
  --input-focus-box-shadow:0 0 8px rgba(82, 168, 236, 0.6);
  --alert-color:#c09853;
  --alert-background-color:#fcf8e3;
  --alert-border-color:#fbeed5;
  --alert-success-color:#468847;
  --alert-success-background-color:#dff0d8;
  --alert-success-border-color:#d6e9c6;
  --alert-error-color:#b94a48;
  --alert-error-background-color:#f2dede;
  --alert-error-border-color:#eed3d7;
  --alert-info-color:#3a87ad;
  --alert-info-background-color:#d9edf7;
  --alert-info-border-color:#bce8f1;
  --panel-background:#fcfcfc;
  --panel-border-color:#ddd;
  --panel-color:#333;
  --modal-background:#f0f0f0;
  --modal-color:#333;
  --modal-box-shadow:2px 0 5px 0 #ccc;
  --pagination-link-color:#333;
  --pagination-border-color:#ddd;
  --category-color:#333;
  --category-background-color:#fffcd7;
  --category-border-color:#d5d458;
  --category-link-color:#000;
  --category-link-hover-color:#000;
  --item-border-color:#ddd;
  --item-padding:5px;
  --item-title-link-font-weight:600;
  --item-status-read-title-link-color:#777;
  --item-status-read-title-focus-color:#777;
  --item-meta-focus-color:#777;
  --item-meta-li-color:#aaa;
  --current-item-border-width:3px;
  --current-item-border-color:#bce;
  --current-item-box-shadow:none;
  --entry-header-border-color:#ddd;
  --entry-header-title-link-color:#333;
  --entry-content-color:#555;
  --entry-content-code-color:#333;
  --entry-content-code-background:#f0f0f0;
  --entry-content-code-border-color:#ddd;
  --entry-content-quote-color:#666;
  --entry-content-abbr-border-color:#999;
  --entry-enclosure-border-color:#333;
  --parsing-error-color:#333;
  --feed-parsing-error-background-color:#fcf8e3;
  --feed-parsing-error-border-style:solid;
  --feed-parsing-error-border-color:#f9e883;
  --feed-has-unread-background-color:#dfd;
  --feed-has-unread-border-style:solid;
  --feed-has-unread-border-color:#bee6bc;
  --category-has-unread-background-color:#dfd;
  --category-has-unread-border-style:solid;
  --category-has-unread-border-color:#bee6bc;
  --keyboard-shortcuts-li-color:#333;
  --counter-color:#666
}
html {
  color-scheme: light;
}
:root {
  --entry-content-font-weight:300;
  --entry-content-font-family:Georgia, 'Times New Roman', Times, serif;
  --entry-content-quote-font-family:var(--entry-content-font-family)
}
* {
  margin:0;
  padding:0;
  box-sizing:border-box
}
html {
  -webkit-text-size-adjust:100%;
  -ms-text-size-adjust:100%
}
body {
  font-family:var(--font-family);
  text-rendering:optimizeLegibility;
  color:var(--body-color);
  background:var(--body-background);
}
hr {
  border:0;
  height:0;
  border-top:1px dotted var(--hr-border-color);
  padding-bottom:10px
}
h1,
h2,
h3 {
  color:var(--title-color)
}
main {
  padding-left:5px;
  padding-right:5px;
  margin-bottom:30px
}

a {
  color:var(--link-color);
}
a:focus {
  outline:0;
  color:var(--link-focus-color);
  text-decoration:none;
  outline:1px dotted #aaa
}
a:hover {
  color:var(--link-hover-color);
  text-decoration:none !important;
}
body > header {
  margin-top:12px;
  margin-bottom:20px
}
.search {
  margin-top: -10px;
}
#scroll {
  display: none;
}
.item-icons {
  display: none
}
body > header ul {
  text-align: left;
}
body > header li {
  display: inline;
    cursor:pointer;
  padding: 0;
  padding-right: 15px;
  font-size: 1em;
}
.logo {
  font-size: .9em;
  margin-right: 15px;
}
body > header * {
  text-transform: capitalize;
}
body > header li a:hover {
  color:#888
}
body > header a {
  color:var(--header-link-color);
  text-decoration:none;
  border:none;
  font-weight:400
}
body > header .active a {
  color:var(--header-active-link-color);
  font-weight:600
}
body > header a:hover {
  color:var(--header-link-hover-color)
}
body > header a:focus {
  color:var(--header-link-focus-color)
}
.page-header h2 {
  font-weight:500;
  font-size: 1.5em;
  border-bottom:1px dotted var(--page-header-title-border-color)
}
.page-header h2 a {
  text-decoration:none;
  color:var(--page-header-title-color)
}
.page-header h2 a:hover,
.page-header h2 a:focus {
  color:#666
}
#nav-counter, .items-count {
  font-size: .9em;
  font-weight: 300;
  color: var(--counter-color)
}
@media(min-width:620px) {
  body {
    margin:auto;
    max-width:750px
  }
}
ul.item-menu {
  padding-top: 2px;
}
ul.item-menu li, ul.item-menu a {
  color: var(--item-meta-focus-color)
}
ul.item-menu a:hover {
  color: #333 !important;;
}
[data-item-page="unread"] ul.item-menu li:nth-child(2) {
  display: none;
}
[data-item-page="unread"] ul.item-menu li:nth-child(4) {
  border: none
}
ul.item-menu li:nth-child(5)::before {
  content: "";
  display: block;
}
ul.item-menu li:nth-child(n+5) a,
[data-item-page="feeds"] .item-menu a {
  color: #777;
  font-size: 1.3em;
  display: inline-block;
  margin-top: 7px;
}
.feed-last-checked {
	color: var(--item-meta-focus-color);
}
[data-item-page="feeds"] article .feed-groups {
  display: none;
}
@media only screen and (min-width:480px) {
  body > header ul li.hide-desktop {
    display:initial
  }
}
@media only screen and (min-width:690px) {
  body > header ul li.hide-desktop {
    display:none
  }
}
@media only screen and (max-width:690px) {
  body > header ul li.hide-mobile {
    display:none
  }
  body > header ul {
    text-align: right
  }
}
h1, h2, h3 {
  color: var(--title-color);
}
.page h1 {
  font-size: 2em;
  line-height: 1.25em;
  margin: 5px 0 30px;
  overflow-wrap: break-word;
  font-family: var(--font-family);
  font-weight: bold;
  margin-bottom: 25px;
  margin-top: 20px;
}
.page h1 a {
  color: inherit;
  font-size: 1em;
}
.item-infos {
  font-family: var(--font-family);
  font-size: 0.9em;
}
.item-infos a {
  font-size: 1em !important;
}
.item-infos li:nth-child(3) {
  display: none;
}