* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --tinta: #19221e;
    --bosque: #17483d;
    --papel: #f5f7f2;
    --coral: #f16d53;
    --lima: #ddf45b;
}

body {
    font-family: "Trebuchet MS", Arial, sans-serif;
    background-color: var(--papel);
    color: var(--tinta);
}

nav {
    background-color: var(--tinta);
    color: white;
    padding: 14px max(24px, calc((100vw - 1180px) / 2));
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 28px;
    border-bottom: 3px solid var(--coral);
    animation: entrada-suave 550ms ease-out both;
}

.tituloprincipal {
    flex: 0 0 auto;
}

.marca-sitio {
    color: white;
    font-size: 16px;
    font-weight: 700;
}

.menu li a[aria-current="page"] {
    color: var(--lima);
    text-decoration: underline;
    text-decoration-color: var(--coral);
    text-underline-offset: 6px;
}

.logo-sitio {
    display: block;
    width: 560px;
    max-width: 80vw;
    height: auto;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: entrada-logo 800ms cubic-bezier(0.2, 0.7, 0.2, 1) 100ms both;
}

.menu {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: 25px;
}

.menu li a {
    color: white;
    text-decoration: none;
    font-size: 16px;
}

.menu li a:hover {
    color: var(--lima);
}

.header {
    min-height: 450px;
    background-image:
        linear-gradient(rgba(12, 20, 17, 0.78), rgba(12, 20, 17, 0.78)),
        url("fondo.png");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.page-banner {
    min-height: 156px;
    border-bottom: 4px solid var(--coral);
}

.page-banner .logo-sitio {
    width: 260px;
}

.inicio-intro {
    padding-top: 72px;
    padding-bottom: 72px;
    background-color: var(--papel);
}

.inicio-intro h1 {
    max-width: 760px;
    color: var(--bosque);
    font-size: 42px;
    line-height: 1.15;
}

.inicio-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
    margin-top: 32px;
}

.inicio-enlace {
    display: grid;
    align-content: start;
    gap: 12px;
    padding: 24px;
    border-top: 3px solid var(--coral);
    border-radius: 2px;
    background-color: white;
    box-shadow: 0 2px 8px rgba(25, 34, 30, 0.06);
    color: var(--tinta);
    text-decoration: none;
    transition: transform 180ms ease, box-shadow 180ms ease;
}

.inicio-enlace strong {
    color: var(--bosque);
    font-size: 20px;
}

.inicio-enlace:hover,
.inicio-enlace:focus-visible {
    transform: translateY(-3px);
    box-shadow: 0 7px 16px rgba(0, 0, 0, 0.14);
}

a:focus-visible {
    outline: 3px solid var(--coral);
    outline-offset: 3px;
}


.seccion {
    padding: 64px 24px;
    scroll-margin-top: 20px;
}

.contenedor {
    width: min(1080px, 100%);
    margin: 0 auto;
}

.sobrelinea {
    margin-bottom: 10px;
    color: var(--coral);
    font-size: 13px;
    font-weight: 700;
    text-transform: uppercase;
}

.seccion h1,
.seccion h2 {
    color: var(--bosque);
    font-family: Georgia, "Times New Roman", serif;
    font-size: 32px;
    line-height: 1.2;
}

.introduccion {
    max-width: 680px;
    margin-top: 14px;
    color: #333;
}

.fundamentos,
.acerca {
    background-color: var(--papel);
}

.temas-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
    margin-top: 30px;
}

.tema {
    padding: 24px;
    border-top: 3px solid var(--coral);
    border-radius: 2px;
    background-color: white;
    box-shadow: 0 2px 8px rgba(25, 34, 30, 0.06);
    animation: entrada-suave 600ms ease-out both;
}

.tema:nth-child(2) {
    animation-delay: 120ms;
}

.tema:nth-child(3) {
    animation-delay: 240ms;
}

.tema-numero {
    color: var(--bosque);
    font-size: 12px;
    font-weight: 700;
}

.tema h2 {
    margin: 14px 0 8px;
    font-family: Georgia, "Times New Roman", serif;
    font-size: 24px;
}

.tema p,
.ejercicio p {
    color: #333;
    line-height: 1.6;
}

.ejemplo {
    margin-top: 16px;
    padding-top: 12px;
    border-top: 1px solid #d9dfe7;
    font-size: 14px;
}

.tutoriales {
    background-color: #eaf0e8;
}

.tutoriales-layout {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    align-items: start;
    gap: 48px;
}

.lista-pasos {
    display: grid;
    gap: 16px;
    margin-top: 26px;
    list-style: none;
}

.lista-pasos li {
    display: grid;
    grid-template-columns: 130px 1fr;
    gap: 12px;
    padding-top: 12px;
    border-top: 1px solid #c8d0c9;
}

.lista-pasos strong {
    color: var(--bosque);
}

.ejemplo-codigo {
    padding: 24px;
    border-radius: 2px;
    background-color: var(--tinta);
    color: white;
}

.ejemplo-codigo pre {
    overflow-x: auto;
    margin: 16px 0;
    color: #b9d8ff;
    font-family: Consolas, monospace;
    line-height: 1.6;
}

.nota-codigo {
    color: #d4dbe4;
    font-size: 14px;
}

.ejercicios {
    background-color: white;
}

.ejercicios-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 24px;
    margin-top: 30px;
}

.ejercicio {
    padding-top: 16px;
    border-top: 2px solid var(--coral);
}

.ejercicio h3 {
    margin: 10px 0 8px;
    color: var(--bosque);
    font-family: Georgia, "Times New Roman", serif;
    font-size: 20px;
}

.errores {
    background-color: var(--papel);
    color: var(--tinta);
}

.errores .sobrelinea {
    color: var(--bosque);
}

.errores h1 {
    color: var(--bosque);
    font-size: 36px;
}

.errores .introduccion {
    color: #3b4740;
    font-size: 17px;
    line-height: 1.7;
}

.errores-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
    margin-top: 28px;
}

.errores-grid > div {
    padding: 22px;
    border: 1px solid #d3dfd4;
    border-top: 4px solid var(--coral);
    border-radius: 6px;
    background-color: white;
    box-shadow: 0 3px 10px rgba(25, 34, 30, 0.07);
}

.errores-grid dt {
    margin-bottom: 8px;
    color: var(--bosque);
    font-size: 18px;
    font-weight: 700;
    line-height: 1.4;
}

.errores-grid dd {
    color: #3b4740;
    font-size: 16px;
    line-height: 1.6;
}

.acerca-contenido {
    max-width: 760px;
}

.acerca-contenido > p:last-child {
    margin-top: 14px;
    color: #333;
    line-height: 1.7;
}

footer {
    background-color: var(--tinta);
    color: white;
    text-align: center;
    padding: 30px;
    border-top: 3px solid var(--coral);
    animation: entrada-suave 650ms ease-out 380ms both;
}

footer a {
    color: var(--lima);
}

footer a:hover {
    color: white;
}

footer .footer-dato {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 8px;
    margin: 0;
}

footer .footer-icono {
    width: 18px;
    height: 18px;
}

footer .footer-contenido {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 24px;
    width: min(1080px, 100%);
    margin: 0 auto;
    text-align: left;
}

footer .footer-contacto {
    display: grid;
    gap: 8px;
    min-width: 0;
}

footer .footer-programacion {
    display: block;
    width: 44px;
    height: 44px;
}

footer h2 {
    margin-bottom: 10px;
}

@keyframes entrada-suave {
    from {
        opacity: 0;
        transform: translateY(14px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes entrada-logo {
    from {
        opacity: 0;
        transform: translate(-50%, -46%) scale(0.96);
    }

    to {
        opacity: 1;
        transform: translate(-50%, -50%) scale(1);
    }
}

@media (prefers-reduced-motion: reduce) {
    nav,
    .logo-sitio,
    .tema,
    footer,
    .inicio-enlace {
        animation: none;
        transition: none;
    }
}


/* -----------------------------
   RESPONSIVE
------------------------------ */

@media (max-width: 700px) {

    nav {
        flex-direction: column;

        gap: 20px;
    }

    .menu {
        gap: 15px;
        flex-wrap: wrap;
        justify-content: center;
    }

    .inicio-intro h1 {
        font-size: 34px;
    }

    .inicio-grid {
        grid-template-columns: 1fr;
    }

    .seccion {
        padding: 48px 20px;
    }

    .temas-grid,
    .tutoriales-layout,
    .ejercicios-grid,
    .errores-grid {
        grid-template-columns: 1fr;
    }

    .lista-pasos li {
        grid-template-columns: 1fr;
        gap: 4px;
    }
}