/* 
   VARIABLES GLOBALES
 */
:root {
    --bg: #0f172a;          /* fondo general (slate-900) */
    --panel: #111827;       /* paneles/cards (gray-900) */
    --text: #e5e7eb;        /* texto principal (gray-200) */
    --muted: #9ca3af;       /* texto secundario (gray-400) */
    --accent: #38bdf8;      /* acento (sky-400) */
    --accent-2: #818cf8;    /* acento secundario (indigo-400) */
    --border: rgba(148,163,184,0.25);
    --shadow: rgba(0,0,0,0.35);
    --sans: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Arial;
}

/*
   RESET BÁSICO
*/
* {
    box-sizing: border-box;
}
html, body {
    height: 100%;
}
body {
    margin: 0;
    font-family: var(--sans);
    color: var(--text);
    background-image: url("../recursosVisuales/background.jpg");
    background-attachment: fixed;
    display: flex;
    flex-direction: column;
    line-height: 1.55;
}

body::before{
    content: "";
    position: fixed;
    inset: 0;
    background-color: rgba(10, 20, 35, 0.20); /* oscurece la imagen */
    z-index: -1;
}

/* 
   CABECERA
*/
.site-header {
    padding: 28px 16px;
    text-align: center;
    background: rgba(56,189,248,0.08);
    border-bottom: 1px solid rgba(56,189,248,0.25);
}

.site-header h1 {
    margin: 0 0 8px;
    font-size: clamp(1.4rem, 2.3vw, 2rem);
    font-weight: 800;
    letter-spacing: .2px;
    background: linear-gradient(90deg, var(--accent), var(--accent-2));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.site-header p {
    margin: 0;
    color: var(--muted);
    font-size: clamp(.95rem, 1.6vw, 1.05rem);
}

/*
LOGO Y SUBTÍTULO EN CABECERA
*/
.header-subtitle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 1.05rem;
    color: var(--muted);
    margin-top: 6px;
}

.header-subtitle b {
    color: var(--text);
    font-weight: 700;
    font-size: 1.1rem;
}

.logo-css {
    width: 35px;
    height: auto;
    filter: drop-shadow(0 0 6px rgba(56,189,248,0.5));
    transition: transform 0.3s ease;
}

.logo-css:hover {
    transform: scale(1.15) rotate(3deg);
    filter: drop-shadow(0 0 16px rgba(56,189,248,0.8));
}

/*
NAVEGACIÓN
*/
.site-nav {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
    padding: 12px 16px;
    background: rgba(0,0,0,0.2);
    border-bottom: 1px solid var(--border);
}

.site-nav a {
    color: var(--text);
    text-decoration: none;
    padding: 8px 12px;
    border-radius: 10px;
    border: 1px solid var(--border);
    transition: transform .15s ease, background .15s ease, border-color .15s ease, color .15s ease;
    font-weight: 600;
    font-size: .98rem;
}

.site-nav a:hover {
    transform: translateY(-1px);
    background: rgba(56,189,248,0.12);
    border-color: var(--accent);
}

/* Clase activa en navegación */
.site-nav a.badge {
    border-color: var(--accent);
    background: rgba(56,189,248,0.16);
    color: #dbeafe;
}

/*
CONTENIDO PRINCIPAL
*/
.content {
    width: 100%;
    max-width: 1280px;
    margin: 24px auto;
    padding: 0 24px 25px;
    flex: 1;
}

/*
TARJETAS / CARDS
*/
.card {
    background: rgba(17,24,39,0.92);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 18px 16px;
    box-shadow: 0 12px 34px var(--shadow);
}

.card h2 {
    margin: 0 0 10px;
    font-size: clamp(1.2rem, 2vw, 1.6rem);
    color: var(--accent);
}

.card p {
    margin: 8px 0;
    color: #d1d5db;
}

.card strong {
    color: #ffffff;
}

/* 
BOTÓN CTA
*/
.cta-btn {
    display: inline-block;
    background: linear-gradient(90deg, #ff6a00, #ffaa00);
    color: #fff;
    padding: 12px 28px;
    border-radius: 9px;
    font-weight: bold;
    text-decoration: none;
    font-size: 1.1rem;
    box-shadow: 0 5px 20px rgba(255,147,23,0.4);
    transition: all 0.4s ease;
}

.cta-btn:hover {
    transform: translateY(-3px);
    background: linear-gradient(90deg, #ffaa00, #ff6a00);
    box-shadow: 0 6px 18px rgba(255,147,23,0.6);
}

/* 
TARJETAS DINÁMICAS
*/
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.topic-card {
    display: block;
    background: rgba(15,17,25,0.7);
    padding: 1.3rem;
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 12px;
    text-decoration: none;
    color: #e0e0e0;
    transition: all 0.4s ease;
}

.topic-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 10px 22px rgba(0,0,0,0.4);
    border-color: #38bdf8;
    background: rgba(20,25,40,0.9);
}

.topic-card h3 {
    color: #6cc4ff;
    margin-bottom: 0.5rem;
}

/*
SECCIÓN DE INFORMACIÓN
*/
.info-section {
    text-align: center;
    max-width: 1250px;
    margin: 20px auto;
    background: rgba(15,23,42,0.85);
    border-radius: 16px;
    padding: 15px 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.45);
    overflow: visible;
}

.info-section h2 {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 0.6rem;
}

.section-subtitle {
    color: var(--muted);
    font-size: 1.05rem;
    margin-bottom: 2.5rem;
}

.learn-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 22px;
    justify-items: stretch;
    align-items: stretch;
    margin-top: 2rem;
}

.learn-item {
    position: relative;
    border-radius: 14px;
    text-decoration: none;
    color: #fff;
    border: 1px solid rgba(255,255,255,0.08);
    box-shadow: 0 6px 25px rgba(0,0,0,0.4);
    transition: all 0.35s ease;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: stretch;
    min-height: 360px;
    padding: 10px 10px;
    opacity: 0.30;
    filter: brightness(0.9) contrast(0.9);
}

/* Hover: */
.learn-item:hover {
    opacity: 1;
    filter: brightness(1.08) contrast(1.1);
    transform: translateY(-8px) scale(1.04);
    box-shadow: 0 18px 35px rgba(56,189,248,0.4);
    border-color: var(--accent);
}

.learn-content {
    position: relative;
    z-index: 2;
    background: rgba(10,15,25,0.78);
    backdrop-filter: blur(6px);
    padding: 20px;
    text-align: center;
    border-top: 1px solid rgba(255,255,255,0.08);
}

.learn-content h3 {
    font-size: 1.2rem;
    margin-bottom: .4rem;
    color: #ffffff;
}

.learn-content p {
    font-size: 0.9rem;
    color: #dbeafe;
    line-height: 1.4;
}

/* 
EFECTOS VISUALES DE PREVIEW
*/
.gradient-demo {
    background: linear-gradient(120deg, #ff512f, #ff0080, #38bdf8, #00ffff);
    background-size: 400% 400%;
    animation: gradientShift 6s ease-in-out infinite;
}

@keyframes gradientShift {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

.gradient-radial-demo {
    background: radial-gradient(circle at center, #00f5c9, #005fff);
    animation: pulseRadial 5s ease-in-out infinite;
}

.rgba-demo {
    background: linear-gradient(135deg, rgba(255,99,132,0.35), rgba(54,162,235,0.35));
    position: relative;
    border: 3px solid rgba(255,255,255,0.4);
    backdrop-filter: blur(4px);
}

.rgba-demo::before {
    content: "";
    position: absolute;
    inset: 0;
    background: repeating-linear-gradient(
        45deg,
        rgba(255,255,255,0.15) 0,
        rgba(255,255,255,0.15) 10px,
        rgba(255,255,255,0.05) 10px,
        rgba(255,255,255,0.05) 20px
        );
    mix-blend-mode: overlay;
    animation: patternSlide 6s linear infinite;
}

@keyframes patternSlide {
    0% {
        background-position: 0 0;
    }
    100% {
        background-position: 100% 100%;
    }
}

.outline-demo {
    background: #0e172a;
    border: 2px solid rgba(255,255,255,0.3);
    outline: 4px solid #38bdf8;
    outline-offset: 4px;
    animation: outlinePulse 3.5s ease-in-out infinite;
}

/*
ANIMACIONES GENERALES
*/
@keyframes fadeUp {
    0% {
        opacity: 0;
        transform: translateY(50px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

.card, .hero-text, .topic-card .side-menu {
    animation: fadeUp 0.8s ease forwards;
}

@keyframes pulseBox {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

.preview-box {
    height: 180px;
    border-radius: 12px;
    margin-top: 16px;
    overflow: hidden;
    box-shadow: 0 0 20px rgba(0,0,0,0.35);
    border: 1px solid rgba(255,255,255,0.1);
    transition: transform .3s ease, box-shadow .3s ease;
    animation: pulseBox 2.8s ease-in-out infinite;
}

.preview-box:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 28px rgba(0,0,0,0.55);
}

/* No se si me gusta o no 
@keyframes pulseGlow {
  0%, 100% {
    transform: scale(1);
    box-shadow: 0 0 16px rgba(56,189,248,0.25);
    filter: brightness(1);
  }
  50% {
    transform: scale(1);
    box-shadow: 0 0 35px rgba(56,189,248,0.7);
    filter: brightness(1.15);
  }
}*/

/*
FOOTER
*/

.site-footer {
    text-align: center;
    align-self: center;
}