/* =========================================
   1. RESET Y ESTILOS GENERALES
   ========================================= */
* {
    box-sizing: border-box; 
}

body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333; 
    background-color: #f4f4f9; 
}

/* =========================================
   2. HEADER Y NAVEGACIÓN
   ========================================= */
header {
    background-color: #2c3e50;
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    height: 70px;
}

h2 {
    font-weight: 300; /* CORREGIDO: Sin px */
    margin: 0;
    font-size: 1.5rem;
}

nav ul {
    display: flex; 
    list-style: none;
    gap: 30px;
    margin: 0;
    padding: 0;
}

nav li {
    cursor: pointer;
    font-weight: 500; /* CORREGIDO: Sin px */
    transition: color 0.4s;
}

nav li:hover {
    color: #3498db;
}

/* =========================================
   3. ESTRUCTURA PRINCIPAL
   ========================================= */
section {
    display: flex;
    min-height: calc(100vh - 70px); 
}

aside {
    background-color: #ffffff;
    width: 250px;
    border-right: 1px solid #ddd;
    padding-top: 20px;
    flex-shrink: 0;
}

aside > ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding: 0;
    margin: 0;
}

aside li {
    padding: 12px 20px;
    cursor: pointer;
    border-left: 4px solid transparent;
    transition: all 0.2s;
}

aside li:hover {
    background-color: #f0f0f0;
    border-left: 4px solid #3498db;
    color: #3498db;
}

/* =========================================
   4. CONTENIDO PRINCIPAL
   ========================================= */
.main-content {
    flex-grow: 1;
    padding: 40px;
    display: flex;
    flex-direction: column;
    gap: 30px;
}

article {
    background-color: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05); 
    border: none;
}

article > h3 {
    margin-top: 0;
    color: #2c3e50;
    border-bottom: 2px solid #3498db;
    display: inline-block;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

/* =========================================
   5. FORMULARIO DE CARGA
   ========================================= */
.upload-form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.drop-zone {
    border: 2px dashed #cbd5e0;
    border-radius: 10px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    background-color: #f8fafc;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.drop-zone:hover {
    border-color: #3498db;
    background-color: #ebf8ff;
}

.drop-zone .icon {
    font-size: 50px;
}

.drop-zone .text {
    font-weight: 600;
    color: #4a5568;
}

.drop-zone .subtext {
    font-size: 0.85rem;
    color: #a0aec0;
}

.btn-convertir {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    align-self: flex-start;
    transition: background-color 0.2s;
}

.btn-convertir:hover {
    background-color: #2980b9;
}