/* VARIABLES Y ESTILOS GLOBALES */
:root {
    --color-primary: #1F70B8;
    --color-primary-dark: #145a9a;
    --color-secondary: #f4f4f4;
    --color-text: #333333;
    --color-text-light: #ffffff;
    --color-background: #ffffff;
    --color-border: #dddddd;
    --color-error: #d93025;
    
    --font-family-base: 'Open Sans', sans-serif;
    
    --spacing-unit: 1rem; /* 16px */
    
    --transition-speed: 250ms;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 5rem; /* Offset for fixed header */
}

body {
    font-family: var(--font-family-base);
    color: var(--color-text);
    background-color: var(--color-background);
    line-height: 1.6;
    font-size: 100%; /* Base font size (usually 16px) */
}

.container {
    width: 90%;
    max-width: 1100px;
    margin-left: auto;
    margin-right: auto;
}

h1, h2, h3 {
    line-height: 1.2;
    font-weight: 700;
}

h1 { font-size: clamp(2rem, 5vw, 3rem); }
h2 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h3 { font-size: 1.25rem; }

img {
    max-width: 100%;
    display: block;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: 8px;
    z-index: 100;
    transition: top var(--transition-speed) ease-in-out;
}

.skip-link:focus {
    top: 0;
}

/* ESTILOS DE FOCO VISIBLE (Heurística 2.4.7 AA) */
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
    border-radius: 2px;
}


/* BOTÓN */
.button {
    display: inline-block;
    padding: 0.75em 1.5em;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    cursor: pointer;
    border: 2px solid transparent;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

.button--primary {
    background-color: var(--color-primary);
    color: var(--color-text-light);
}

.button--primary:hover, .button--primary:focus-visible {
    background-color: var(--color-primary-dark);
}


/* HEADER Y NAVEGACIÓN */
.header {
    background-color: var(--color-primary);
    padding: var(--spacing-unit) 0;
    position: sticky;
    top: 0;
    z-index: 10;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.header__container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header__logo {
    height: 50px;
    width: auto;
    filter: brightness(0) invert(1);
}

.nav__toggle {
    display: none;
    background: transparent;
    border: none;
    cursor: pointer;
}

.nav__list {
    list-style: none;
    display: flex;
    gap: calc(var(--spacing-unit) * 1.5);
}

.nav__link {
    color: var(--color-text-light);
    text-decoration: none;
    font-weight: 600;
    padding: 0.5rem 0;
    position: relative;
}

.nav__link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--color-text-light);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-speed) ease;
}

.nav__link:hover::after, .nav__link:focus-visible::after {
    transform: scaleX(1);
}

/* HERO SECTION */
.hero {
    background-color: var(--color-secondary);
    padding: calc(var(--spacing-unit) * 4) 0;
    text-align: center;
}

.hero__container {
    display: grid;
    grid-template-columns: 1fr;
    gap: calc(var(--spacing-unit) * 2);
    align-items: center;
}

.hero__text {
    max-width: 60ch;
    margin: 0 auto;
}

.hero__subtitle {
    font-size: 1.125rem;
    margin: var(--spacing-unit) 0 calc(var(--spacing-unit) * 2);
}

.hero__image {
    border-radius: 8px;
    object-fit: cover;
    aspect-ratio: 16 / 9;
}


/* SECCIONES GENERALES */
.section {
    padding: calc(var(--spacing-unit) * 4) 0;
}

.section--light {
    background-color: var(--color-secondary);
}

.section__title {
    text-align: center;
    margin-bottom: calc(var(--spacing-unit) * 3);
    color: var(--color-primary);
}


/* CARDS (Presentación, Profesorado, Precios) */
.card {
    background: var(--color-background);
    padding: calc(var(--spacing-unit) * 1.5);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.card__title {
    margin-bottom: 0.5rem;
}

.presentation-grid, .team-grid, .pricing-grid {
    display: grid;
    gap: calc(var(--spacing-unit) * 1.5);
}

.card--team .card__image {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    margin: 0 auto 1rem;
    object-fit: cover;
}

.card--team .card__subtitle {
    color: #666;
    margin-bottom: 1rem;
}

.card--team .card__link {
    font-weight: 600;
    color: var(--color-primary);
}

.card--pricing .card__price {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-primary);
    margin: 1rem 0;
}


/* ACORDEÓN (Programa, FAQ) */
.accordion {
    max-width: 750px;
    margin: 0 auto;
}

.accordion__heading { margin: 0; }

.accordion__trigger {
    width: 100%;
    background: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    padding: var(--spacing-unit);
    text-align: left;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 0.5rem;
}

.accordion__trigger:hover {
    background-color: #f9f9f9;
}

.accordion__icon {
    width: 1em;
    height: 1em;
    border: 2px solid currentColor;
    border-radius: 50%;
    position: relative;
    transition: transform var(--transition-speed);
}

.accordion__icon::before, .accordion__icon::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    background-color: currentColor;
    transform: translate(-50%, -50%);
    transition: transform var(--transition-speed);
}
.accordion__icon::before { width: 50%; height: 2px; }
.accordion__icon::after { width: 2px; height: 50%; }

.accordion__trigger[aria-expanded="true"] .accordion__icon {
    transform: rotate(45deg);
}
.accordion__trigger[aria-expanded="true"] .accordion__icon::after {
    transform: translate(-50%, -50%) rotate(90deg);
}

.accordion__panel {
    padding: var(--spacing-unit);
    border: 1px solid var(--color-border);
    border-top: 0;
    border-radius: 0 0 4px 4px;
}
.accordion__panel ul {
    list-style-position: inside;
    margin-top: 1rem;
}

/* TIMELINE (Calendario) */
.timeline {
    position: relative;
    max-width: 600px;
    margin: 0 auto;
    padding-left: calc(var(--spacing-unit) * 2);
}
.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: var(--color-primary);
}
.timeline__item {
    position: relative;
    margin-bottom: calc(var(--spacing-unit) * 2);
}
.timeline__item::before {
    content: '';
    position: absolute;
    left: -2rem;
    top: 0.25rem;
    width: 1rem;
    height: 1rem;
    border-radius: 50%;
    background: var(--color-background);
    border: 3px solid var(--color-primary);
    transform: translateX(-50%);
}
.timeline__date {
    font-weight: 700;
    color: var(--color-primary);
}


/* FORMULARIO */
.form {
    max-width: 600px;
    margin: 0 auto;
}

.form__group {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

.form__label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.form__input, .form__textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: 4px;
    font-size: 1rem;
    font-family: var(--font-family-base);
}

.form__input[aria-invalid="true"] {
    border-color: var(--color-error);
}

.form__error {
    color: var(--color-error);
    font-size: 0.875rem;
    margin-top: 0.25rem;
    display: block;
    min-height: 1.2em; /* Prevents layout shift */
}

#form-status {
    margin-top: 1rem;
    font-weight: 600;
}


/* FOOTER */
.footer {
    background-color: #222;
    color: #eee;
    padding: calc(var(--spacing-unit) * 3) 0;
}

.footer__container {
    display: grid;
    gap: calc(var(--spacing-unit) * 2);
}

.footer__title {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-unit);
}

.footer__list {
    list-style: none;
}

.footer__link {
    color: #ccc;
    text-decoration: none;
}
.footer__link:hover, .footer__link:focus-visible {
    text-decoration: underline;
}

.footer__bottom {
    grid-column: 1 / -1;
    text-align: center;
    border-top: 1px solid #444;
    padding-top: var(--spacing-unit);
    font-size: 0.875rem;
    color: #aaa;
}


/* MEDIA QUERIES - RESPONSIVE DESIGN */
@media (min-width: 768px) {
    .presentation-grid { grid-template-columns: repeat(2, 1fr); }
    .team-grid { grid-template-columns: repeat(2, 1fr); }
    .pricing-grid { grid-template-columns: repeat(3, 1fr); }
    .hero__container { grid-template-columns: 2fr 1fr; text-align: left; }
    .hero__text { margin: 0; }
    .footer__container { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1024px) {
    .team-grid { grid-template-columns: repeat(4, 1fr); }
}

@media (max-width: 767px) {
    .nav__toggle { display: block; }
    .nav {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--color-primary);
        transform: scaleY(0);
        transform-origin: top;
        transition: transform var(--transition-speed) ease-in-out;
    }
    .nav--open {
        transform: scaleY(1);
    }
    .nav__list {
        flex-direction: column;
        padding: var(--spacing-unit);
    }
    .nav__link {
        display: block;
        padding: var(--spacing-unit);
    }
}