/* ================================
      ESTILO CIENTÍFICO MINIMAL
   ================================ */

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

body {
    background: #fafbfc;
    font-family: 'Inter', 'Segoe UI', Roboto, Arial, sans-serif;
    color: #1a1f2b;
    line-height: 1.7;
}

/* -------- HEADER -------- */

header {
    padding: 60px 20px;
    text-align: center;
    background: #ffffff;
    border-bottom: 1px solid #e4e7ef;
}

header h1 {
    font-size: 36px;
    font-weight: 600;
    color: #233044;
    margin-bottom: 10px;
}

header p {
    font-size: 16px;
    color: #455166;
    opacity: 0.8;
}

/* -------- NAV SUPER MINIMAL -------- */

nav {
    display: flex;
    justify-content: center;
    gap: 28px;
    background: transparent;
    padding: 18px;
    border-bottom: 1px solid #e4e7ef;
    position: sticky;
    top: 0;
    backdrop-filter: blur(10px);
}

nav a {
    text-decoration: none;
    font-weight: 500;
    color: #1b3a6f;
    padding-bottom: 5px;
    transition: 0.2s;
}

nav a:hover {
    color: #003bff;
    border-bottom: 2px solid #003bff;
}

/* -------- CONTENEDOR PRINCIPAL -------- */

main {
    width: 88%;
    max-width: 850px;
    margin: auto;
    padding: 40px 0;
}

/* -------- SECCIONES SIN CAJAS -------- */

section {
    margin-bottom: 55px;
}

section h2 {
    font-size: 28px;
    padding-bottom: 6px;
    border-bottom: 2px solid #dce3f2;
    color: #233044;
    margin-bottom: 22px;
}

section p, li {
    font-size: 17px;
    color: #2a3144;
}

/* -------- LISTAS -------- */

ul, ol {
    margin-left: 25px;
    margin-top: 10px;
}

/* -------- ECUACIONES -------- */
.eq {
    text-align: center;
    margin: 22px 0;
    font-size: 20px;
}

/* -------- TABLAS ULTRALIMPIAS -------- */

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
    font-size: 16px;
}

th {
    text-align: left;
    padding: 10px 5px;
    color: #233044;
    border-bottom: 2px solid #d5d9e2;
}

td {
    padding: 10px 5px;
    border-bottom: 1px solid #e8ebf2;
}

/* -------- BOTONES MINIMALISTAS -------- */

.btn {
    display: inline-block;
    padding: 10px 18px;
    background: #1b3a6f;
    color: white;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    margin: 5px 4px;
    transition: 0.25s;
}

.btn:hover {
    background: #003bff;
}

/* -------- FOOTER -------- */

footer {
    text-align: center;
    padding: 35px;
    margin-top: 50px;
    color: #455166;
    border-top: 1px solid #e4e7ef;
    background: #ffffff;
}

/* -------- RESPONSIVE -------- */

@media (max-width: 768px) {

    nav {
        flex-wrap: wrap;
        gap: 16px;
    }

    header h1 {
        font-size: 28px;
    }

    main {
        width: 92%;
    }
}