:root,
::backdrop {
    --sans-font: -apple-system, BlinkMacSystemFont, "Avenir Next", Avenir, "Nimbus Sans L", Roboto, "Noto Sans", "Segoe UI", Arial, Helvetica, "Helvetica Neue", sans-serif;
    --mono-font: Consolas, Menlo, Monaco, "Andale Mono", "Ubuntu Mono", monospace;
    --standard-border-radius: 5px;
    --bg: #fff;
    --accent-bg: #f5f7ff;
    --text: #212121;
    --text-light: #585858;
    --border: #898ea4;
    --accent: #0d47a1;
    --accent-hover: #1266e2;
    --accent-text: var(--bg);
    --code: #d81b60;
    --preformatted: #444;
    --marked: #fd3;
    --disabled: #efefef
}

@media (prefers-color-scheme:dark) {

    :root,
    ::backdrop {
        color-scheme: dark;
        --bg: #212121;
        --accent-bg: #2b2b2b;
        --text: #dcdcdc;
        --text-light: #ababab;
        --accent: #ffb300;
        --accent-hover: #ffe099;
        --accent-text: var(--bg);
        --code: #f06292;
        --preformatted: #ccc;
        --disabled: #111
    }

    img,
    video {
        opacity: .8
    }
}

*,
:before,
:after {
    box-sizing: border-box
}

textarea,
select,
input,
progress {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none
}

html {
    font-family: var(--sans-font);
    scroll-behavior: smooth
}

body {
    color: var(--text);
    background-color: var(--bg);
    grid-template-columns: 1fr min(45rem, 90%) 1fr;
    margin: 0;
    font-size: 1.15rem;
    line-height: 1.5;
    display: grid
}

body>* {
    grid-column: 2
}

body>header {
    background-color: var(--accent-bg);
    border-bottom: 1px solid var(--border);
    text-align: center;
    grid-column: 1/-1;
    padding: 0 .5rem 2rem
}

body>header>:only-child {
    margin-block-start: 2rem
}

body>header h1 {
    max-width: 1200px;
    margin: 1rem auto
}

body>header p {
    max-width: 40rem;
    margin: 1rem auto
}

main {
    padding-top: 1.5rem
}

body>footer {
    color: var(--text-light);
    text-align: center;
    border-top: 1px solid var(--border);
    margin-top: 4rem;
    padding: 2rem 1rem 1.5rem;
    font-size: .9rem
}

h1 {
    font-size: 3rem
}

h2 {
    margin-top: 3rem;
    font-size: 2.6rem
}

h3 {
    margin-top: 3rem;
    font-size: 2rem
}

h4 {
    font-size: 1.44rem
}

h5 {
    font-size: 1.15rem
}

h6 {
    font-size: .96rem
}

p {
    margin: 1.5rem 0
}

p,
h1,
h2,
h3,
h4,
h5,
h6 {
    overflow-wrap: break-word
}

h1,
h2,
h3 {
    line-height: 1.1
}

@media only screen and (width<=720px) {
    h1 {
        font-size: 2.5rem
    }

    h2 {
        font-size: 2.1rem
    }

    h3 {
        font-size: 1.75rem
    }

    h4 {
        font-size: 1.25rem
    }
}

a,
a:visited {
    color: var(--accent)
}

a:hover {
    text-decoration: none
}

button,
.button,
a.button,
input[type=submit],
input[type=reset],
input[type=button],
label[type=button] {
    border: 1px solid var(--accent);
    background-color: var(--accent);
    color: var(--accent-text);
    padding: .5rem .9rem;
    line-height: normal;
    text-decoration: none
}

.button[aria-disabled=true],
input:disabled,
textarea:disabled,
select:disabled,
button[disabled] {
    cursor: not-allowed;
    background-color: var(--disabled);
    border-color: var(--disabled);
    color: var(--text-light)
}

input[type=range] {
    padding: 0
}

abbr[title] {
    cursor: help;
    text-decoration-line: underline;
    text-decoration-style: dotted
}

button:enabled:hover,
.button:not([aria-disabled=true]):hover,
input[type=submit]:enabled:hover,
input[type=reset]:enabled:hover,
input[type=button]:enabled:hover,
label[type=button]:hover {
    background-color: var(--accent-hover);
    border-color: var(--accent-hover);
    cursor: pointer
}

.button:focus-visible,
button:focus-visible:where(:enabled),
input:enabled:focus-visible:where([type=submit], [type=reset], [type=button]) {
    outline: 2px solid var(--accent);
    outline-offset: 1px
}

header>nav {
    padding: 1rem 0 0;
    font-size: 1rem;
    line-height: 2
}

header>nav ul,
header>nav ol {
    flex-flow: wrap;
    place-content: space-around center;
    align-items: center;
    margin: 0;
    padding: 0;
    list-style-type: none;
    display: flex
}

header>nav ul li,
header>nav ol li {
    display: inline-block
}

header>nav a,
header>nav a:visited {
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    color: var(--text);
    margin: 0 .5rem 1rem;
    padding: .1rem 1rem;
    text-decoration: none;
    display: inline-block
}

header>nav a:hover,
header>nav a.current,
header>nav a[aria-current=page] {
    border-color: var(--accent);
    color: var(--accent);
    cursor: pointer
}

@media only screen and (width<=720px) {
    header>nav a {
        border: none;
        padding: 0;
        line-height: 1;
        text-decoration: underline
    }
}

aside,
details,
pre,
progress {
    background-color: var(--accent-bg);
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    margin-bottom: 1rem
}

aside {
    float: right;
    width: 30%;
    margin-inline-start: 15px;
    padding: 0 15px;
    font-size: 1rem
}

[dir=rtl] aside {
    float: left
}

@media only screen and (width<=720px) {
    aside {
        float: none;
        width: 100%;
        margin-inline-start: 0
    }
}

article,
fieldset,
dialog {
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    margin-bottom: 1rem;
    padding: 1rem
}

article h2:first-child,
section h2:first-child,
article h3:first-child,
section h3:first-child {
    margin-top: 1rem
}

section {
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    margin: 3rem 0;
    padding: 2rem 1rem
}

section+section,
section:first-child {
    border-top: 0;
    padding-top: 0
}

section+section {
    margin-top: 0
}

section:last-child {
    border-bottom: 0;
    padding-bottom: 0
}

details {
    padding: .7rem 1rem
}

summary {
    cursor: pointer;
    word-break: break-all;
    margin: -.7rem -1rem;
    padding: .7rem 1rem;
    font-weight: 700
}

details[open]>summary+* {
    margin-top: 0
}

details[open]>summary {
    margin-bottom: .5rem
}

details[open]>:last-child {
    margin-bottom: 0
}

table {
    border-collapse: collapse;
    margin: 1.5rem 0
}

figure>table {
    width: max-content;
    margin: 0
}

td,
th {
    border: 1px solid var(--border);
    text-align: start;
    padding: .5rem
}

th {
    background-color: var(--accent-bg);
    font-weight: 700
}

tr:nth-child(2n) {
    background-color: var(--accent-bg)
}

table caption {
    margin-bottom: .5rem;
    font-weight: 700
}

textarea,
select,
input,
button,
.button {
    font-size: inherit;
    border-radius: var(--standard-border-radius);
    box-shadow: none;
    max-width: 100%;
    margin-bottom: .5rem;
    padding: .5rem;
    font-family: inherit;
    display: inline-block
}

textarea,
select,
input {
    color: var(--text);
    background-color: var(--bg);
    border: 1px solid var(--border)
}

label {
    display: block
}

textarea:not([cols]) {
    width: 100%
}

select:not([multiple]) {
    background-image: linear-gradient(45deg, transparent 49%, var(--text)51%), linear-gradient(135deg, var(--text)51%, transparent 49%);
    background-position: calc(100% - 15px), calc(100% - 10px);
    background-repeat: no-repeat;
    background-size: 5px 5px, 5px 5px;
    padding-inline-end: 25px
}

[dir=rtl] select:not([multiple]) {
    background-position: 10px, 15px
}

input[type=checkbox],
input[type=radio] {
    vertical-align: middle;
    width: min-content;
    position: relative
}

input[type=checkbox]+label,
input[type=radio]+label {
    display: inline-block
}

input[type=radio] {
    border-radius: 100%
}

input[type=checkbox]:checked,
input[type=radio]:checked {
    background-color: var(--accent)
}

input[type=checkbox]:checked:after {
    content: " ";
    border-right: solid var(--bg).08em;
    border-bottom: solid var(--bg).08em;
    background-color: #0000;
    border-radius: 0;
    width: .18em;
    height: .32em;
    font-size: 1.8em;
    position: absolute;
    top: .05em;
    left: .17em;
    transform: rotate(45deg)
}

input[type=radio]:checked:after {
    content: " ";
    background-color: var(--bg);
    border-radius: 100%;
    width: .25em;
    height: .25em;
    font-size: 32px;
    position: absolute;
    top: .125em;
    left: .125em
}

@media only screen and (width<=720px) {

    textarea,
    select,
    input {
        width: 100%
    }
}

input[type=color] {
    height: 2.5rem;
    padding: .2rem
}

input[type=file] {
    border: 0
}

hr {
    background: var(--border);
    border: none;
    height: 1px;
    margin: 1rem auto
}

mark {
    border-radius: var(--standard-border-radius);
    background-color: var(--marked);
    color: #000;
    padding: 2px 5px
}

mark a {
    color: #0d47a1
}

img,
video {
    border-radius: var(--standard-border-radius);
    max-width: 100%;
    height: auto
}

figure {
    margin: 0;
    display: block;
    overflow-x: auto
}

figure>img,
figure>picture>img {
    margin-inline: auto;
    display: block
}

figcaption {
    text-align: center;
    color: var(--text-light);
    margin-block: 1rem;
    font-size: .9rem
}

blockquote {
    border-inline-start: .35rem solid var(--accent);
    color: var(--text-light);
    margin-block: 2rem;
    margin-inline: 2rem 0;
    padding: .4rem .8rem;
    font-style: italic
}

cite {
    color: var(--text-light);
    font-size: .9rem;
    font-style: normal
}

dt {
    color: var(--text-light)
}

code,
pre,
pre span,
kbd,
samp {
    font-family: var(--mono-font);
    color: var(--code)
}

kbd {
    color: var(--preformatted);
    border: 1px solid var(--preformatted);
    border-bottom: 3px solid var(--preformatted);
    border-radius: var(--standard-border-radius);
    padding: .1rem .4rem
}

pre {
    color: var(--preformatted);
    max-width: 100%;
    padding: 1rem 1.4rem;
    overflow: auto
}

pre code {
    color: var(--preformatted);
    background: 0 0;
    margin: 0;
    padding: 0
}

progress {
    width: 100%
}

progress:indeterminate {
    background-color: var(--accent-bg)
}

progress::-webkit-progress-bar {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent-bg)
}

progress::-webkit-progress-value {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent)
}

progress::-moz-progress-bar {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent);
    transition-property: width;
    transition-duration: .3s
}

progress:indeterminate::-moz-progress-bar {
    background-color: var(--accent-bg)
}

dialog {
    max-width: 40rem;
    margin: auto
}

dialog::backdrop {
    background-color: var(--bg);
    opacity: .8
}

@media only screen and (width<=720px) {
    dialog {
        max-width: 100%;
        margin: auto 1em
    }
}

sup,
sub {
    vertical-align: baseline;
    position: relative
}

sup {
    top: -.4em
}

sub {
    top: .3em
}

.notice {
    background: var(--accent-bg);
    border: 2px solid var(--border);
    border-radius: var(--standard-border-radius);
    margin: 2rem 0;
    padding: 1.5rem
}

body>header {
    background: repeat url(ptx-bg-light.svg)
}

@media (prefers-color-scheme: dark) {
    body>header {
        background: url(ptx-bg-dark.svg)
    }
}