/* ---------- Design tokens ---------- */
:root {
    color-scheme: light;

    /* Colors */
    --bg: #ffffff;
    --surface: #ffffff;
    --text: #1f1d1a;
    --muted: #6b655c;
    --line: #d9d3c8;
    --link-selected: #000080; /* Links use the browser's default color until hovered or selected. */

    /* Spacing: every margin, padding, and gap below uses this scale.
       1  inside small things: tag height, a key's sides, a short list gap
       2  closely related items: tag to tag, icon to label, heading to its text
       3  separate blocks of text, button sides, panel padding
       4  a heading to its content, group to group
       5  inside cards, around large images
       6  section to section
       7  the top and bottom of the page */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 1rem;
    --space-4: 1.5rem;
    --space-5: 2rem;
    --space-6: 3rem;
    --space-7: 4.5rem;

    /* Widths. All page content shares the same left and right edges. */
    --content-width: min(1100px, 100% - 2 * var(--space-3));
    --reading-width: min(800px, 100% - 2 * var(--space-3));
    --card-w: min(680px, 84vw);

    /* Height of one row in the navigation panel. */
    --row: 2.25rem;
}

/* ---------- Base ---------- */
*, *::before, *::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding-bottom: var(--space-4);
    background: var(--bg);
    color: var(--text);
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
}

/* Selection is shown by darkening links, not by a border around them. */
:focus-visible {
    outline: none;
}

/* Keeps a keyboard-selected link from landing right against the edge of the screen. */
a {
    scroll-margin-block: var(--space-4);
    text-underline-offset: 0.2em;
}

a:hover,
a:focus,
.card:hover a,
.card:focus a {
    color: var(--link-selected);
    text-decoration-thickness: 2px;
}

hr {
    width: var(--content-width);
    margin: var(--space-6) auto;
    border: 0;
    border-top: 1px solid var(--line);
}

h1,
h2 {
    line-height: 1.1;
    letter-spacing: -0.02em;
    text-box-trim: both;
    text-box-edge: cap alphabetic;
}

h1 {
    margin: 0 0 var(--space-3);
    font-size: clamp(2.25rem, 6vw, 3.5rem);
}

h2 {
    width: var(--content-width);
    margin: 0 auto var(--space-4);
    font-size: clamp(1.5rem, 3vw, 2rem);
}

kbd {
    padding: 0 var(--space-1);
    border: 1px solid var(--line);
    border-radius: 4px;
    color: var(--text);
    font-family: inherit;
    font-size: 0.875em;
}

/* ---------- Header ---------- */
header {
    width: var(--content-width);
    margin: 0 auto;
    padding-top: var(--space-7);
}

.abstract {
    margin: 0;
    color: var(--muted);
    font-size: 1.125rem;
}

.abstract + .abstract {
    margin-top: var(--space-3);
}

/* Icon inside a line of text. Kept shorter than the line so the spacing stays even. */
.inline-icon {
    height: 1.4em;
    vertical-align: -0.35em;
}

.socials {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-1) var(--space-4);
    margin-top: var(--space-3);
}

.socials a {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
}

.socials img {
    width: 1.125rem;
    height: 1.125rem;
}

/* ---------- Mode instructions ---------- */
.mode-help {
    width: var(--content-width);
    margin: var(--space-4) auto 0;
    padding: var(--space-3);
    border: 1px solid var(--line);
    border-radius: 8px;
    color: var(--muted);
    font-size: 0.9375rem;
}

.mode-help p {
    margin: 0;
}

.mode-help ul {
    margin: var(--space-1) 0;
    padding-left: var(--space-4);
}

.mode-help strong {
    color: var(--text);
}

/* ---------- Carousel ---------- */
/* Every card sits in the same grid cell, so the stage is as tall as the tallest card. */
.carousel-stage {
    display: grid;
    align-items: center;
    justify-content: center;
    padding: var(--space-4) 0;
    overflow: hidden;
    cursor: grab;
    touch-action: pan-y;
    -webkit-user-select: none;
    user-select: none;
    mask-image: linear-gradient(to right, transparent, #000 var(--space-4), #000 calc(100% - var(--space-4)), transparent);
}

/* With one card there's nothing to drag to. */
.carousel-stage:has(.card:only-child) {
    cursor: default;
}

.card {
    position: relative;
    grid-area: 1 / 1;
    width: var(--card-w);
    overflow: hidden;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 12px;
    cursor: pointer;
    transition: transform 0.45s ease, opacity 0.45s ease;
}

.card.is-active {
    cursor: inherit;
}

/* While dragging, cards follow the pointer directly instead of animating. */
.carousel-stage.is-dragging,
.carousel-stage.is-dragging .card {
    cursor: grabbing;
}

.carousel-stage.is-dragging .card {
    transition: none;
}

.card.is-hidden {
    pointer-events: none;
}

.card-image,
.project-image {
    display: block;
    width: 100%;
    height: auto;
}

.card-image {
    border-bottom: 1px solid var(--line);
}

.card-body {
    padding: clamp(var(--space-4), 4vw, var(--space-5));
}

.card h3 {
    margin: 0 0 var(--space-2);
    font-size: clamp(1.5rem, 3vw, 2rem);
    line-height: 1.25;
}

/* Hovering or selecting a card treats its title like a selected link, with or without a link in it. */
.card:hover h3,
.card:focus h3 {
    color: var(--link-selected);
    text-decoration: underline 2px;
    text-underline-offset: 0.2em;
}

/* A side card's link only selects the card, like the rest of the card does. */
.card:not(.is-active) a {
    pointer-events: none;
}

.card p {
    margin: 0 0 var(--space-4);
    color: var(--muted);
    font-size: clamp(1rem, 2vw, 1.1875rem);
}

.tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    margin: 0;
    padding: 0;
    list-style: none;
}

.tags li {
    padding: var(--space-1) var(--space-3);
    border: 1px solid var(--line);
    border-radius: 999px;
    font-size: clamp(0.8125rem, 1.5vw, 0.9375rem);
}

/* ---------- Project pages ---------- */
.project-page {
    width: var(--reading-width);
    margin: 0 auto;
    padding-top: var(--space-6);
    font-size: 1.125rem;
}

.project-image {
    margin-bottom: var(--space-5);
    border: 1px solid var(--line);
    border-radius: 12px;
}

.project-page p {
    margin: 0 0 var(--space-3);
}

.project-page ul {
    margin: 0;
    padding-left: var(--space-4);
}

.project-page li + li {
    margin-top: var(--space-2);
}

/* Follows the narrower reading column rather than the home page's dividers. */
.project-page h2 {
    width: auto;
    margin: var(--space-6) 0 var(--space-3);
}

.up-layer {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    margin-top: var(--space-6);
    padding: var(--space-2) var(--space-3);
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 8px;
    font-size: 1rem;
    text-decoration: none;
}

/* ---------- Footer ---------- */
footer {
    width: var(--content-width);
    margin: var(--space-6) auto 0;
    padding-top: var(--space-4);
    border-top: 1px solid var(--line);
    color: var(--muted);
    font-size: 0.9375rem;
}

/* Lines up with the narrower reading column. */
.project-page ~ footer {
    width: var(--reading-width);
}

/* ---------- Side navigation ---------- */
/* In scroll mode only the lines show. In navigation mode they open up:
   the lines stay put and spread apart, and each name slides out from its own line. */
.side-nav {
    --pop: cubic-bezier(0.34, 1.4, 0.64, 1); /* Overshoots slightly, then settles. */
    position: fixed;
    top: 50%;
    left: 0;
    z-index: 1000; /* Above the carousel cards. */
    width: 1.75rem;
    padding: var(--space-3) 0;
    overflow: hidden;
    cursor: pointer;
    transform: translateY(-50%);
    transition: width 0.3s var(--pop);
}

.nav-mode .side-nav {
    /* script.js sets --label-width to the widest name. */
    width: calc(var(--label-width) + var(--space-6));
    cursor: default;
}

.side-nav ul {
    margin: 0;
    padding: 0;
    list-style: none;
}

.side-nav a {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    height: 0.875rem;
    text-decoration: none;
    white-space: nowrap;
    transition: height 0.3s ease;
}

.nav-mode .side-nav a {
    height: var(--row);
}

/* The line */
.side-nav a::before {
    content: "";
    flex: none;
    width: 0.75rem;
    border-top: 2px solid var(--muted);
    transition: width 0.2s ease, border-color 0.2s ease;
}

body:not(.nav-mode) .side-nav:hover a::before,
.nav-mode .side-nav a:hover::before,
.nav-mode .side-nav a:focus::before {
    border-color: var(--link-selected);
}

.nav-mode .side-nav a:hover::before,
.nav-mode .side-nav a:focus::before {
    width: 1.25rem;
}

/* The name. Screen readers still get it while it's hidden. */
.side-nav span {
    flex: none;
    opacity: 0;
    transform: translateX(calc(-1 * var(--space-3)));
    transition: opacity 0.15s ease, transform 0.15s ease;
}

.nav-mode .side-nav span {
    opacity: 1;
    transform: none;
    /* Each name follows the one above it. script.js sets --index. */
    transition: opacity 0.2s ease, transform 0.3s var(--pop);
    transition-delay: calc(var(--index) * 35ms + 60ms);
}

.nav-mode .side-nav a:hover,
.nav-mode .side-nav a:focus {
    text-decoration: underline;
}

@media (prefers-reduced-motion: reduce) {
    .card,
    .side-nav,
    .side-nav a,
    .side-nav a::before,
    .side-nav span {
        transition: none !important;
    }
}