html {
    --dark: rgb(34, 40, 49);
    --lighter-dark: rgb(57, 62, 70);
    --blue: rgb(0, 102, 255);
    --light-blue: rgb(59, 137, 255);
    --dark-blue: rgb(0, 64, 160);
    --red: rgb(255, 0, 0);
    --light-red: rgb(255, 150, 150);
    --dark-red: rgb(166, 0, 0);
    --green: rgb(0, 184, 0);
    --light-green: rgb(151, 255, 151);
    --dark-green: rgb(0, 117, 0);
    --yellow: rgb(255, 221, 0);
    --light-yellow: rgb(255, 243, 162);
    --dark-yellow: rgb(169, 146, 0);
    --light: rgb(238, 238, 238);
    --shadow-col: rgba(57, 62, 70, 0.3);

    --header-bg-col: var(--dark);
    --nav-hover-col: var(--lighter-dark);
    --header-text-col: var(--light);
    --body-bg-col: var(--light);

    --content-container-bg-col: var(--light);
    --main-text-col: var(--dark);
    --footer-bg-col: var(--dark);
    --footer-text-col: var(--light);

    --link-col: var(--dark-blue);
    --link-hover-col: var(--light-blue);

    --button-col: var(--light-blue);
    --button-hover-col: var(--blue);
    --pos-button-col: var(--green);
    --pos-button-hover-col: var(--dark-green);
    --neg-button-col: var(--red);
    --neg-button-hover-col: var(--dark-red);
    --button-text-col: var(--light);
    --button-border: none;

    --subheadline-opacity: 0.5;

    --content-width: 60%;
    --popup-size-factor: 0.6;
    --card-width: 60%;
}

html.high-contrast {
    --dark: black;
    --lighter-dark: rgb(57, 62, 70);
    --blue: rgb(0, 0, 158);
    --light-blue: var(--blue);
    --dark-blue: var(--blue);
    --red: red;
    --light-red: var(--red);
    --dark-red: var(--red);
    --green: green;
    --light-green: var(--green);
    --dark-green: var(--green);
    --yellow: yellow;
    --light-yellow: var(--yellow);
    --dark-yellow: var(--yellow);
    --light: white;
    --shadow-col: rgba(57, 62, 70, 0.3);

    --button-border: 1px solid white;
    --subheadline-opacity: 1;
}

html.dark-mode {
    --content-container-bg-col: var(--dark);
    --body-bg-col: var(--dark);
    --main-text-col: var(--light);
    --header-bg-col: var(--lighter-dark);
    --footer-bg-col: var(--lighter-dark);
    --nav-hover-col: var(--dark);
    --shadow-col: rgba(255, 255, 255, 0.3);
    --link-col: var(--light-blue);
}

html.dark-mode.high-contrast {
    --blue: rgb(93, 93, 255);
}

* {
    box-sizing: border-box;
    padding: 0;
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
}

a {
    color: var(--link-col);
    text-decoration: none;
    transition: 0.3s;
}

a:hover {
    color: var(--link-hover-col);
}

h1 {
    font-size: 30px;
    color: var(--main-text-col);
}

h2 {
    font-size: 25px;
}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    background-color: red;
    background-color: var(--body-bg-col);
}

header {
    position: relative;
    background-color: var(--header-bg-col);
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: flex-end;
    color: var(--header-text-col);
    font-size: 20px;
}

header > nav {
    display: flex;
    flex-direction: row;
    z-index: 50;
}

header > nav > a {
    flex: 1;
    padding: 20px 10px 20px 10px;
    transition: 0.3s;
    text-decoration: none;
    color: var(--header-text-col);
    white-space: nowrap;
}

header > nav > a:hover {
    background-color: var(--nav-hover-col);
    color: var(--header-text-col);
}

#nav-open-btn {
    padding: 20px 10px 20px 10px;
    transition: 0.3s;
    text-decoration: none;
    color: var(--header-text-col);
    background-color: var(--header-bg-col);
    border: none;
    font-size: inherit;
    height: 100%;
    display: flex;
    flex-direction: column;
}

#nav-open-btn:hover {
    background-color: var(--nav-hover-col);
}

#nav-open-btn > div {
    margin: 2px;
    width: 25px;
    height: 1px;
    border: 2px solid var(--header-text-col);
}

.content-container {
    padding: 10px;
    flex: 1;
    background-color: var(--content-container-bg-col);
    width: var(--content-width);
    align-self: center;
    color: var(--main-text-col);
}

@media screen and (width >= 600px) {
    #nav-open-btn {
        display: none;
    }

    #nav-open-btn-label {
        display: none;
    }
}

@media screen and (width < 1000px) {
    html {
        --content-width: 80%;
        --popup-size-factor: 0.7;
        --card-width: 70%;
    }
}

@media screen and (width < 600px) {
    header > nav {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        right: 0;
        background-color: var(--header-bg-col);
        border-bottom-left-radius: 10px;
        overflow: hidden;
        /* transition: 0.3s; */
        transform-origin: center top;
        transform: scaleY(0);
    }

    header > nav.open {
        transform: scaleY(1);
    }

    header > nav > a {
        flex: 1;
        padding: 10px 20px 10px 20px;
    }

    html {
        --content-width: 95%;
        --popup-size-factor: 1;
        --card-width: 100%;
    }
}

footer {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    color: var(--footer-text-col);
    padding: 10px;
    background-color: var(--footer-bg-col);
}

footer a {
    color: var(--footer-text-col);
    text-decoration: none;
}

.imageContentElement {
    max-width: 100%;
    max-height: 400px;
    width: auto;
    height: auto;
}

.textContentElement {
    margin-top: 5px;
    margin-bottom: 5px;
    font-size: 18px;
}

.flex-container {
    display: flex;
}

.flex-container > * {
    flex: 1;
}

.flex-container.row {
    flex-direction: row;
}

.flex-container.col {
    flex-direction: column;
}

.flex-container.center {
    align-items: center;
    justify-content: center;
}

.flex-container.end {
    justify-content: flex-end;
}

.flex-container.start {
    justify-content: flex-start;
}

.button {
    position: relative;
    border: var(--button-border);
    background-color: var(--button-col);
    color: var(--button-text-col);
    padding: 5px;
    border-radius: 5px;
    font-size: 18px;
    margin: 5px;
    transition: 0.3s;
    cursor: pointer;
    flex: 1;
}

.button:hover {
    background-color: var(--button-hover-col);
}

.button.pos {
    background-color: var(--pos-button-col);
}

.button.pos:hover {
    background-color: var(--pos-button-hover-col);
}

.button.neg {
    background-color: var(--neg-button-col);
}

.button.neg:hover {
    background-color: var(--neg-button-hover-col);
}

.header-left-alignment-container {
    display: flex;
    flex-direction: row;
    width: 100%;
}

.header-btn {
    margin: 10px;
    flex: 0;
    white-space: nowrap;
}

.textbox {
    padding: 10px;
    border: 1px solid var(--main-text-col);
    border-radius: 5px;
    margin: 5px;
    color: var(--main-text-col);
    background-color: var(--content-container-bg-col);
}

.register-textarea {
    padding: 10px;
    border: 1px solid var(--main-text-col);
    border-radius: 5px;
    margin: 5px;
    resize: none;
    background-color: var(--content-container-bg-col);
}

.content-card {
    width: var(--card-width);
    border-radius: 10px;
    box-shadow: 0 0 10px var(--shadow-col);
    padding: 20px;
    flex-grow: 0;
    position: relative;
    overflow: hidden;
}

.popup-container {
    position: fixed;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(57, 62, 70, 0.3);
    backdrop-filter: blur(5px);
    z-index: 100;
}

.popup-container * {
    z-index: 101;
}

.popup {
    overflow: hidden;
    padding: 10px;
    position: relative;
    border-radius: 10px;
    width: calc(var(--content-width) * var(--popup-size-factor));
    min-height: 50px;
    background-color: var(--content-container-bg-col);
    animation: appear 0.5s;
    color: var(--main-text-col);
}

@keyframes appear {
    0% {
        transform: scale(0.5);
    }
    100% {
        transform: scale(1);
    }
}

@keyframes fade-in {
    0% {
        opacity: 0%;
    }
    100% {
        opacity: 100%;
    }
}

.popup-close-btn {
    position: absolute;
    top: 0;
    right: 0;
    border: none;
    color: var(--light);
    cursor: pointer;
    background-color: var(--neg-button-col);
    font-size: 20px;
    padding: 5px;
    border-bottom-left-radius: 5px;
}

.popup-buttons {
    margin-top: 20px;
    display: flex;
    flex-direction: column;
}

.overlay-msg {
    z-index: 200;
    position: absolute;
    top: 0;
    left: 50%;
    width: fit-content;
    padding: 10px;
    border-radius: 0px 0px 10px 10px;
    background-color: var(--body-bg-col);
    border-color: var(--main-text-col);
    color: var(--main-text-col);
    border: 2px solid;
    border-top: none;
    border-left: 10px solid;
    min-width: 15%;
    text-align: center;
    font-weight: bold;
    font-size: 20px;
    transform: translateY(-100%) translateX(-50%);
    transition: 0.3s;
}

.overlay-msg.error {
    background-color: var(--body-bg-col);
    border-color: var(--red);
}

.overlay-msg.warning {
    background-color: var(--body-bg-col);
    border-color: var(--yellow);
}

.overlay-msg.correct {
    background-color: var(--body-bg-col);
    border-color: var(--green);
}

.overlay-msg.open {
    transform: translateY(0) translateX(-50%);
}

.label-span {
    margin: 5px;
}

.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    /* background-color: rgba(57, 62, 70, 0.3); */
    backdrop-filter: blur(5px);
    z-index: 300;
    animation: fade-in 0.3s;
}

.loading-overlay::after {
    content: ' ';
    align-self: center;
    display: block;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    border: 5px solid;
    border-color: var(--blue) transparent var(--blue) transparent;
    animation-name: rotate;
    animation-duration: 1s;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
}

@keyframes rotate {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.headline-container {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    width: fit-content;
    justify-content: center;
    margin-bottom: 15px;
    max-width: 100%;
    overflow: hidden;
    flex: 1;
}

.subheadline {
    font-size: 12px;
    color: var(--main-text-col);
    opacity: var(--subheadline-opacity);
}

.wireframe {
    display: block;
    width: 100%;
    background-color: blue;
    position: relative;
}

.wireframe::before {
    position: absolute;
    content: ' ';
    height: max-content;
    background-color: rgb(200, 200, 200);
    width: 100%;
    height: 100%;
}

.post-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
}

.post-card {
    position: relative;
    padding: 10px;
    border-radius: 5px;
    border-radius: 10px;
    overflow: hidden;
    cursor: pointer;
    transition: 0.3s;
}

.post-card:hover {
    box-shadow: 0 0 10px var(--shadow-col);
}

.post-card * {
    position: relative;
    z-index: 3;
}

@media screen and (width >= 1000px) {
    .hide-on-big {
        display: none !important;
    }
}

@media screen and (width < 1000px) {
    .post-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .hide-on-medium {
        display: none !important;
    }

    .header-btn {
        margin: 5px;
        font-size: 1rem;
    }
}

@media screen and (width < 650px) {
    .post-grid {
        grid-template-columns: repeat(1, 1fr);
    }

    .hide-on-small {
        display: none !important;
    }

    .header-btn {
        white-space: normal;
    }
}

.post-img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 50%;
    object-fit: cover;
    z-index: 1;
}

.post-img-overlay {
    content: ' ';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 50%;
    z-index: 2;
    background-image: linear-gradient(
        rgba(255, 255, 255, 0.7) 40%,
        var(--content-container-bg-col)
    );
}

.hidden {
    display: none !important;
}

.list-table {
    width: 100%;
    border-collapse: collapse;
}

.list-table th {
    font-size: 20px;
    text-align: left;
    padding: 5px;
}

.list-table td {
    font-size: 20px;
    padding: 5px;
}

.list-table tr {
    transition: 0.3s;
}

.list-table tr:hover {
    cursor: pointer;
    backdrop-filter: brightness(0.7);
}

.list-table tr:nth-child(2n) {
    background-color: var(--shadow-col);
}

/* https://gabriele-strache.de/uebersetzungen/css-unsichtbarer-seiteninhalt/ */
.sr-only {
    clip: rect(1px, 1px, 1px, 1px);
    clip-path: inset(50%);
    height: 1px;
    width: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
}

.footer-button {
    padding: 2px;
    flex: 0;
    border: none;
    border-radius: 2px;
    background-color: var(--light);
    cursor: pointer;
}

.contrast-button.active {
    background-color: var(--green);
}

.contrast-button > div {
    background-color: var(--dark);
    padding: 2px;
    border-radius: 50%;
}

.contrast-button > div > div {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background-image: linear-gradient(
        to right,
        var(--light) 50%,
        var(--dark) 50%
    );
}

.contrast-button.active > div > div {
    background-image: linear-gradient(
        to right,
        var(--green) 50%,
        var(--dark) 50%
    );
}

.dark-mode-button {
    font-size: 20px;
    background-color: transparent;
}