@font-face {
    font-family: 'Barlow';
    src: url('fonts/barlow/Barlow-Light.ttf') format('truetype');
    font-weight: 300;
    font-style: normal;
}

:root {
    /* Allow UA widgets to match theme */
    color-scheme: light dark;

    /* Light theme defaults */
    --bg: #fbf8f1;
    --text: #140e00;

    --nav-bg: rgba(50, 50, 0, 0.1);

    --side-nav-grad-0: rgba(50, 50, 0, 0);
    --side-nav-grad-1: rgba(50, 50, 0, 0.1);

    --jump-bg: rgba(50, 50, 0, 0.15);
    --jump-bg-hover: rgba(50, 50, 0, 0.25);
}

/* Prefer system setting when supported */
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #13110e;
        --text: #fbf8f1;

        --nav-bg: rgba(255, 255, 255, 0.08);

        --side-nav-grad-0: rgba(255, 255, 255, 0);
        --side-nav-grad-1: rgba(255, 255, 255, 0.08);

        --jump-bg: rgba(255, 255, 255, 0.12);
        --jump-bg-hover: rgba(255, 255, 255, 0.2);
    }
}

/* JS-driven theme (also used as a fallback when prefers-color-scheme isn't supported) */
html[data-theme="dark"] {
    --bg: #050507;
    --text: #fbf8f1;

    --nav-bg: rgba(255, 255, 255, 0.08);

    --side-nav-grad-0: rgba(255, 255, 255, 0);
    --side-nav-grad-1: rgba(255, 255, 255, 0.08);

    --jump-bg: rgba(255, 255, 255, 0.12);
    --jump-bg-hover: rgba(255, 255, 255, 0.2);
}

html[data-theme="light"] {
    --bg: #fbf8f1;
    --text: #140e00;

    --nav-bg: rgba(50, 50, 0, 0.1);

    --side-nav-grad-0: rgba(50, 50, 0, 0);
    --side-nav-grad-1: rgba(50, 50, 0, 0.1);

    --jump-bg: rgba(50, 50, 0, 0.15);
    --jump-bg-hover: rgba(50, 50, 0, 0.25);
}

body {
    margin: 0;
    font-family: 'Barlow Regular', Helvetica, Arial, sans-serif;
    background-color: var(--bg);
    color: var(--text)
}

main {
    max-width: 50rem;
    margin: 0 auto;
    padding: 0 3%;
}

h1, h2 {
    font-family: Georgia, "Times New Roman", serif;
}

h2 {
    margin-bottom: 0;
}

h2 + p {
    margin-top: 0.25rem;
}

p {
    line-height: 1.4;
}

header h1,
header > p {
    max-width: 50rem;
    margin: 0 auto;
    padding: 1.5rem 3% 0.5rem;
}

header > p {
    padding-top: 0;
}

a {
    color: inherit;
}

nav {
    text-align: center;
    background-color: var(--nav-bg);
}

header nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    backdrop-filter: blur(3px);
    z-index: 1000;
}

header {
    padding-top: 3.5rem;
}

nav a,
nav span {
    display: inline-block;
    padding: 1rem;
}

footer nav a {
    font-size: 1.1rem;
    padding: 2rem;
}

ol {
    line-height: 1.4;
}

/* Display math in worked examples - larger, on own line, left-aligned */
h3 + p mjx-container[display="true"] {
    font-size: 1.3em;
    margin: 0.5em 0 1em !important;
    text-align: left !important;
}

/* Side navigation hit area - hidden by default (mobile) */
.side-nav-next {
    display: none;
}

/* Show side nav and hide footer nav on larger screens */
@media (min-width: 900px) {
    .side-nav-next {
        display: block;
        position: fixed;
        right: 0;
        top: 3.7rem;
        height: calc(100vh - 3.7rem);
        width: calc((100vw - 50rem) / 2 - 3rem);
        min-width: 80px;
        cursor: pointer;
    }

    .side-nav-next::after {
        content: '';
        position: absolute;
        inset: 0;
        background:
            url('images/next.svg') no-repeat right 1rem center / 1.5rem,
            linear-gradient(to right, var(--side-nav-grad-0) 0%, var(--side-nav-grad-1) 20%, var(--side-nav-grad-1) 100%);
        opacity: 0;
        transition: opacity 350ms ease-out;
        pointer-events: none;
    }

    .side-nav-next:hover::after {
        opacity: 0.3;
    }

    footer nav {
        display: none;
    }
}

/* Jump to furthest button - right-aligned in nav */
.jump-to-furthest {
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    font-size: 0.9rem;
    padding: 0.4rem 0.8rem;
    background-color: var(--jump-bg);
    border-radius: 4px;
    text-decoration: none;
    transition: background-color 200ms ease;
}

.jump-to-furthest:hover {
    background-color: var(--jump-bg-hover);
}

/* Grayed out lessons on index page */
.lesson-read {
    opacity: 0.5;
}

.lesson-read a {
    color: inherit;
}