:root {
    /* Configurable variables: https://github.com/hakimel/reveal.js/blob/master/css/theme/template/exposer.scss */
    --r-main-font: InterVariable, sans-serif;
    --primary-color: #c23939;
    --selection-color: #c23939;
    --r-heading-color: #ccc;
    --r-background-color: #333;
    --r-main-color: #ccc;
    --r-main-font-size: 28px;
    --r-link-color: var(--primary-color);
    --r-link-color-hover: #ef6565;
    --r-block-margin: 1.3em 0;
    --r-heading-margin: .5em 0 1em;
}

/* Vertical gradient, darker at the top, over a heavily faded copy of the title
   slide photo. Lower the gradient alpha to show more of the photo. */
.reveal-viewport {
    background-image:
        linear-gradient(to bottom, rgba(16, 16, 16, 1), rgba(61, 61, 61, 0.98)),
        url('scala_days.jpg');
    background-size: cover;
    background-position: center;
}

.reveal {
    font-weight: 300;
}

.reveal .slides {
    text-align:left;
}

.reveal .slides section,
.reveal .slides section > section,
.reveal p {
  line-height: 1.4;
}

#title-slide {
    display: flex !important;
    flex-direction: column;
    justify-content: center;
    height: 100%;
}

h1.title {
    margin-top: 0;
}

/* The title slide has a photo background (`title-slide-attributes` in
   presentation.md). Its own lettering fills the lower half, so the title sits
   at the top, over a dark fade that keeps it readable. */
#title-slide {
    justify-content: flex-start;
    color: #fff;
    --r-heading-color: #fff;
    --r-link-color: #fff;
    --primary-color: #fff;
}

.reveal .backgrounds > .slide-background:first-child::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(to bottom, rgba(0, 0, 0, 0.8), rgba(0, 0, 0, 0.2) 60%);
}

/* QR code to the slides and paper, in the free space right of the title. */
#title-slide::after {
    content: "";
    background-image: url('qr-code-presentation.svg');
    background-size: contain;
    background-repeat: no-repeat;
    position: absolute;
    display: block;
    top: 14em;
    left: 0;
    width: 7em;
    height: 7em;
}

.reveal pre {
    box-shadow: none;
    line-height: 1.5;
    font-size: 1em;
    width: auto;
}

.reveal code {
    background-color: #2e2e2e;
    font-size: 0.8em;
}

.reveal pre code {
    max-height: none;
    display: block;
    width: auto;
}

.reveal pre.small {
    font-size: 0.9em;
}

:not(pre) code {
    display: inline-block;
    padding: 0.1em 0.3em;
    border-radius: 6px;
}

.reveal small,
.reveal small * {
    vertical-align: inherit;
}

.reveal ul ul {
    margin: 0;
}

.reveal li {
    margin-bottom: 0.25em;
}

pre code.hljs {
    border-radius: 6px;
    padding: 0;
}

code {
    background-color: #444;
}

:not(pre) code {
    background-color: #444;
    display: inline-block;
    padding: 0.1em 0.3em;
    border-radius: 6px;
}

.katex {
    font-size: 1em;
}

.reveal h1 {
    margin-bottom: 0.5em;
    line-height: 1.1;
}

.reveal h1::after {
    content: "";
    display: block;
    width: 3em;
    height: 0.3em;
    background-color: var(--primary-color);
}

.reveal h2 {
    font-size: 1.6em;
}

.reveal h2::after {
    content: "";
    display: block;
    width: 2em;
    height: 0.2em;
    background-color: var(--primary-color);
}

.reveal h3 {
    margin-bottom: 1em;
}

.reveal h3::after {
    content: "";
    display: block;
    width: 1.5em;
    height: 0.15em;
    background-color: var(--primary-color);
}

.reveal ul, .reveal ol {
    display: block;
    margin: var(--r-block-margin);
    padding-left: 1em;
}

.reveal .slides section .fragment {
    opacity: 0.05;
    visibility: visible;
}

.reveal .slides section .fragment.visible {
    opacity: 1;
}

.reveal ::selection {
    background-color: var(--selection-color);
}

#TOC ul {
    columns: 2;
}

.reveal .references {
    margin: 0;
}

.reveal .slide-number {
    font-size: 3vh;
    padding: 0.5vh 1vh;
    right: 1.5vh;
    bottom: 1.5vh;
}

.katex-display {
    margin: 0;
}

/* Display math that is narrower than its column, such as the value grammar,
   sits flush left instead of centered. Apply with `<div class="math-left">`. */
.math-left .katex-display > .katex {
    text-align: left;
}

.hljs {
    background-color: transparent !important;
    color: var(--r-main-color);
}

.column {
    scrollbar-width: none;
}

/* Paragraphs have no bottom margin in this theme, so columns that follow a
   paragraph need their own space. */
.reveal p + .columns {
    margin-top: var(--r-block-margin);
}

.column > *:first-child,
.column > div:first-child > *:first-child,
.column > ul:first-child > li:first-child > *:first-child {
    margin-top: 0;
}

/* Chat bubbles, on the "Strong specifications for agents" slides. */
.chat {
    display: flex;
    flex-direction: column;
    gap: 0.6em;
}

.chat > div {
    max-width: 75%;
    padding: 0.4em 0.9em;
    border-radius: 1em;
}

.chat .me {
    align-self: flex-end;
    background-color: var(--primary-color);
    color: #fff;
}

.chat .agent {
    align-self: flex-start;
    background-color: #555;
}

/* Row of linked QR codes with captions, on the conclusion slide. */
.qr-codes {
    display: flex;
    gap: 1.5em;
    align-items: flex-start;
}

.qr-codes figure {
    margin: 0;
    text-align: center;
}

.reveal .qr-codes img {
    width: 260px;
    margin: 0;
}

.paper {
    box-shadow: 0 0 16px rgba(256, 256, 256, 0.5);
    border-radius: 6px;
    width: 100%;
    height: auto;
}

.reveal .progress {
    height: 4px;
    bottom: 4px;
}

.hljs-comment {
    color: #888888;
}

.hljs-keyword, .hljs-built_in  {
    color: var(--primary-color);
}

/* highlight.js tags Haskell's `let` as a title, which the theme paints like a
   function name. Show it as a keyword instead. */
.language-haskell .hljs-title {
    color: var(--primary-color);
}

.hljs-function .hljs-title {
    color: #527edd;
}

.hljs-type, .hljs-class .hljs-title, .hljs-number {
    color: #e8b23f;
}

.column, .columns {
    overflow: visible !important;
}

div.columns {
    gap: 3.5rem;
}

div.column {
    flex: 1 0 0;
}

/* Dense slides: scale the whole slide down a notch, for code- and math-heavy
   content that cannot be trimmed further. Apply with `## Title {.dense}`. */
.reveal section.dense {
    font-size: 0.85em;
}