:root { --primary: #2563eb; --primary-hover: #1d4ed8; --bg-main: #f8fafc; --bg-card: #ffffff; --text-main: #1e293b; --text-muted: #64748b; }
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: system-ui, sans-serif; background-color: var(--bg-main); color: var(--text-main); line-height: 1.5; }
header { background: var(--bg-card); box-shadow: 0 1px 3px rgba(0,0,0,0.1); position: sticky; top: 0; z-index: 100; }
nav { max-width: 1200px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; padding: 0 20px; height: 60px; }
.logo { font-weight: bold; font-size: 1.2rem; color: var(--primary); text-decoration: none; }
.menu-cursos { display: flex; list-style: none; height: 100%; }
.curso-item { position: relative; height: 100%; display: flex; align-items: center; padding: 0 15px; cursor: pointer; font-weight: 500; }
.curso-item:hover { color: var(--primary); }
.dropdown-cuatris { display: none; position: absolute; top: 100%; left: 0; background: var(--bg-card); min-width: 200px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); list-style: none; border-radius: 0 0 4px 4px; }
.curso-item:hover .dropdown-cuatris { display: block; }
.cuatri-item { position: relative; padding: 10px 15px; color: var(--text-main); }
.cuatri-item:hover { background: #f1f5f9; color: var(--primary); }
.submenu-asignaturas { display: none; position: absolute; top: 0; left: 100%; background: var(--bg-card); min-width: 280px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); list-style: none; border-radius: 0 4px 4px 0; }
.cuatri-item:hover .submenu-asignaturas { display: block; }
.asig-item { padding: 10px 15px; color: var(--text-main); cursor: pointer; font-size: 0.9rem; border-bottom: 1px solid #f1f5f9; }
.asig-item:hover { background: #e2e8f0; color: var(--primary); }
main { max-width: 1200px; margin: 40px auto; padding: 0 20px; }
.view-section { display: none; }
.view-section.active { display: block; }
.hero-asig { background: var(--bg-card); padding: 30px; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); margin-bottom: 30px; }
.hero-asig h1 { color: var(--primary); margin-bottom: 10px; }
.section-title { margin: 30px 0 15px 0; font-size: 1.4rem; border-left: 4px solid var(--primary); padding-left: 10px; }
.video-carousel-container { position: relative; margin-bottom: 30px; }
.video-carousel { display: flex; gap: 20px; overflow-x: auto; padding: 10px 5px; scroll-behavior: smooth; border-radius: 8px; }
.video-carousel::-webkit-scrollbar { height: 8px; }
.video-carousel::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 4px; }
.video-card { min-width: 300px; max-width: 300px; background: var(--bg-card); border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); overflow: hidden; display: flex; flex-direction: column; }
.video-card iframe { width: 100%; height: 180px; border: none; }
.video-info { padding: 12px; }
.video-title { font-weight: bold; font-size: 0.95rem; margin-bottom: 5px; }
.btn-fullscreen { background: #e2e8f0; border: none; padding: 4px 8px; font-size: 0.8rem; border-radius: 4px; cursor: pointer; margin-top: 5px; }
.video-modal { display: none; position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.8); z-index: 1000; align-items: center; justify-content: center; }
.video-modal.active { display: flex; }
.modal-content { width: 80%; max-width: 800px; aspect-ratio: 16/9; background: black; position: relative; }
.modal-content iframe { width: 100%; height: 100%; border: none; }
.close-modal { position: absolute; top: -40px; right: 0; color: white; font-size: 1.5rem; cursor: pointer; background: none; border: none; }
.materials-grid { display: grid; grid-template-columns: 2fr 1fr; gap: 30px; }
@media (max-width: 768px) { .materials-grid { grid-template-columns: 1fr; } }
.materials-list { background: var(--bg-card); padding: 20px; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); }
.file-item { display: flex; align-items: center; justify-content: space-between; padding: 10px; border-bottom: 1px solid #f1f5f9; }
.upload-card { background: var(--bg-card); padding: 20px; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); height: fit-content; border: 2px dashed #cbd5e1; }
.form-group { margin-bottom: 15px; }
.form-group label { display: block; font-weight: 500; margin-bottom: 5px; font-size: 0.9rem; }
.form-group input[type="file"] { width: 100%; padding: 10px; background: #f8fafc; border: 1px solid #e2e8f0; border-radius: 4px; }
.btn-submit { width: 100%; background: var(--primary); color: white; border: none; padding: 12px; border-radius: 4px; font-weight: bold; cursor: pointer; }
.btn-submit:hover { background: var(--primary-hover); }