css5

table :nth-col(even) {
    background: #e8f4fd;
}
table :nth-col(3) {
    border-left: 2px solid #3498db;
}

table :nth-last-col(1) {
    background: #fdebd0;
    font-weight: bold;
}

p:column(1) {
    color: #3498db;
}
:column(odd) {
    background: #f8f9fa;
}

:current(slide) {
    background: #f9e79f;
}
:current(p) {
    font-weight: bold;
}

textarea:blank {
    border: 2px solid #e74c3c;
}
div:blank {
    display: none;
}

li:only-child {
    color: #3498db;
    font-style: italic;
}

p:only-of-type {
    border-left: 4px solid #2ecc71;
    padding-left: 10px;
}

@page :first {
    margin-top: 5cm;
}
@page :first {
    background: white;
}

@page :left {
    margin-left: 2cm;
    margin-right: 4cm;
}

@page :right {
    margin-left: 4cm;
    margin-right: 2cm;
}

p::before {
    content: "📌 ";
    color: #e74c3c;
}
blockquote::before {
    content: open-quote;
    font-size: 3em;
}

a::after {
    content: " →";
}
li:last-child::after {
    content: " (dernier)";
    font-size: 0.8em;
}

dialog::backdrop {
    background: linear-gradient(135deg, rgba(0,0,0,0.7), rgba(0,0,0,0.9));
}
video:fullscreen::backdrop {
    background: black;
}

li::marker {
    color: #e74c3c;
    font-weight: bold;
    content: "▶ ";
}
li:last-child::marker {
    content: "✓ ";
}

::selection {
    background: #f1c40f;
    color: #2c3e66;
}
p::selection {
    background: #2ecc71;
    color: white;
}

input:optional {
    border: 1px solid #95a5a6;
}
input:required {
    border-left: 3px solid #e74c3c;
}

input:required {
    background: #fef9e7;
    border-color: #e74c3c;
}
input:required::before {
    content: "* ";
}

input:read-only {
    background: #f8f9fa;
    border: 1px dashed #95a5a6;
}
input:read-write {
    background: white;
    border: 1px solid #3498db;
}

input:read-write {
    border: 2px solid #2ecc71;
}
textarea:read-write {
    background: #d5f5e3;
}

input:in-range {
    border-color: #2ecc71;
}
input:out-of-range {
    border-color: #e74c3c;
    background: #fdebd0;
}

video:fullscreen {
    width: 100vw;
    height: 100vh;
    object-fit: contain;
}
:fullscreen {
    background: black;
}

video:picture-in-picture {
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}
video:picture-in-picture:hover {
    transform: scale(1.02);
}

custom-element:defined {
    display: block;
    border: 2px solid #2ecc71;
    padding: 10px;
}
custom-element:not(:defined) {
    opacity: 0.5;
}

:host {
    display: block;
    background: #f8f9fa;
    border-radius: 8px;
    padding: 10px;
}
:host(.special) {
    background: #f9e79f;
}

::slotted(p) {
    color: #3498db;
    font-weight: bold;
}
::slotted(.important) {
    background: #f9e79f;
}