/* ---
   Hoja de Estilos Universal para Lecciones de "ElGuruJk"
   Versión: 2.1 (Añadidos estilos para el laboratorio de derivadas)
--- */

:root {
    --color-bg: #121212; --color-surface: #1e1e1e; --color-primary: #BB86FC;
    --color-secondary: #03DAC6; --color-text: #e0e0e0; --color-text-secondary: #a0a0a0;
    --color-border: #333; --nav-height: 80px;
}
body.light-mode {
    --color-bg: #f4f4f9; --color-surface: #ffffff; --color-primary: #6200EE;
    --color-secondary: #018786; --color-text: #212121; --color-text-secondary: #5f5f5f;
    --color-border: #ddd;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { 
    font-family: 'Poppins', sans-serif; background-color: var(--color-bg); 
    color: var(--color-text); line-height: 1.7; 
    transition: background-color 0.3s, color 0.3s; padding-top: var(--nav-height);
}
.container { max-width: 1200px; margin: 0 auto; padding: 4rem 2rem; }
h1, h2, h3, h4 { font-weight: 600; margin-bottom: 1rem; color: var(--color-text); }
h1 { font-size: 3rem; }
h2 { font-size: 2.2rem; border-bottom: 3px solid var(--color-primary); padding-bottom: 0.5rem; display: inline-block; }
.section-intro { max-width: 800px; margin: 1rem auto 3rem auto; text-align: center; font-size: 1.1rem; color: var(--color-text-secondary); }
i.fas { margin-right: 0.75rem; color: var(--color-secondary); }

nav {
    position: fixed; top: 0; left: 0; width: 100%; z-index: 1000; background-color: var(--color-surface);
    display: flex; justify-content: space-between; align-items: center; padding: 0 2rem;
    height: var(--nav-height); border-bottom: 1px solid var(--color-border);
}
.back-to-menu { font-size: 1.5rem; color: var(--color-text); text-decoration: none; }
.nav-title { font-size: 1.2rem; font-weight: 600; color: var(--color-text-secondary); position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); pointer-events: none; }
.theme-switcher { display: flex; align-items: center; gap: 0.5rem; }
.switch { position: relative; display: inline-block; width: 60px; height: 34px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #ccc; transition: .4s; border-radius: 34px; }
.slider:before { position: absolute; content: ""; height: 26px; width: 26px; left: 4px; bottom: 4px; background-color: white; transition: .4s; border-radius: 50%; }
input:checked + .slider { background-color: var(--color-primary); }
input:checked + .slider:before { transform: translateX(26px); }

.hero { 
    height: 50vh; min-height: 300px; display: flex; text-align: center; color: #fff;
    background-size: cover; background-position: center;
}
.hero-content { margin: auto; }
.hero .subtitle { font-size: 1.5rem; font-weight: 300; margin-bottom: 2rem; }
.cta-button { display: inline-block; padding: 1rem 2.5rem; border-radius: 50px; text-decoration: none; font-weight: 600; background-color: var(--color-primary); color: #fff; border: 2px solid var(--color-primary); transition: transform 0.3s; }
.cta-button:hover { transform: translateY(-5px); }

.layers-container { display: grid; grid-template-columns: repeat(auto-fit, minmax(350px, 1fr)); gap: 2rem; }
.layer-card { background-color: var(--color-surface); border: 1px solid var(--color-border); border-radius: 10px; overflow: hidden; }
.layer-header { padding: 1.5rem; }
.layer-body { padding: 1.5rem; }

.apps-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1.5rem; }
.app-card { background-color: var(--color-surface); padding: 2rem; text-align: center; border-radius: 10px; border: 1px solid var(--color-border); }
.app-card i { font-size: 3rem; margin-bottom: 1rem; }

/* ======== ESTILOS PARA EL LABORATORIO DE DERIVADAS ======== */
.derivatives-lab { 
    display: grid; grid-template-columns: 350px 1fr; gap: 2rem; 
    background: var(--color-surface); padding: 2rem; border-radius: 15px; 
    border: 1px solid var(--color-border); 
}
.controls-panel { display: flex; flex-direction: column; gap: 1.5rem; }
.input-group { display: flex; flex-direction: column; gap: 0.5rem; }
.input-group label { color: var(--color-text-secondary); font-weight: 600; }
.input-group input[type="text"], .input-group input[type="range"] { 
    width: 100%; padding: 0.8rem; background-color: var(--color-bg); 
    border: 1px solid var(--color-border); border-radius: 5px; 
    color: var(--color-text); font-family: 'Poppins', sans-serif; font-size: 1rem;
}
.input-group input[type="range"] { padding: 0; }
#point-display { text-align: center; font-weight: bold; color: var(--color-primary); background: var(--color-bg); padding: 0.25rem; border-radius: 5px; }

.render-container { background-color: var(--color-bg); border-radius: 8px; min-height: 400px; flex-grow: 1; display: flex; align-items: center; justify-content: center; }
.stats-results { background: var(--color-bg); padding: 1.5rem; border-radius: 8px; }
.stats-results h4 { margin-top: 0; color: var(--color-secondary); }
.stats-results p { font-size: 1.1rem; word-wrap: break-word; }
.stats-results strong { color: var(--color-secondary); }
.stats-results span { font-family: 'Courier New', Courier, monospace; color: var(--color-text); background: var(--color-surface); padding: 2px 6px; border-radius: 4px; }

@media (max-width: 992px) { .derivatives-lab { grid-template-columns: 1fr; } }
@media (max-width: 768px) { .nav-title { display: none; } }