:root {
            --primary: #6366f1;
            /* Indigo */
            --primary-hover: #4f46e5;
            --secondary: #ec4899;
            /* Pink */
            --bg-color: #f8fafc;
            --surface: #ffffff;
            --text-main: #1e293b;
            --text-muted: #64748b;
            --radius-lg: 16px;
            --radius-md: 12px;
            --shadow-soft: 0 10px 25px -5px rgba(0, 0, 0, 0.05);
            --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
            --transition: all 0.3s cubic;
        }

body { font-family: 'Segoe UI', Arial, sans-serif; 
line-height: 1.6; color: #333; 
max-width: 1200px; 
margin: 20px auto; 
padding: 20px; 
background-color: #f9f9f9;
background-image:
                radial-gradient(at 0% 0%, hsla(253, 16%, 7%, 0.05) 0, transparent 50%),
                radial-gradient(at 100% 0%, hsla(339, 49%, 30%, 0.05) 0, transparent 50%);
            
 }



 .fraction { display: inline-block; vertical-align: middle; text-align: center; }
        .fraction > span { display: block; padding: 0 5px; }
        .fraction span.numerator { border-bottom: 1px solid #333; }
        
        
    
 .header-container {
            text-align: center;
            padding: 3rem 1rem;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            box-shadow: var(--shadow-soft);
            margin-bottom: 2rem;
        }
.nav-links {
            display: flex;
            justify-content: center;
            gap: 2rem;
            margin: 2rem 0;
            flex-wrap: wrap;
        }

.nav-links a {
            color: var(--text-muted);
            text-decoration: none;
            font-weight: 600;
            padding: 0.5rem 1.5rem;
            border-radius: 50px;
            background: white;
            box-shadow: var(--shadow-soft);
            transition: var(--transition);
        }
.nav-links a:hover {
            color: var(--primary);
            box-shadow: var(--shadow-hover);
            transform: translateY(-2px);
    }

.tableformula{
margin-left: auto;
  margin-right: auto;
  width:10%;
  border:3px solid #000000;
}
.tableformula td{border:10px;}

table.center {
  margin-left: auto;
  margin-right: auto;
  width:80%;
  border:2px solid #000000;
}
th,td{border:2px solid #000000;}
table.center2 {
  margin-left: auto;
  margin-right: auto;
  border:0px;
  width:60%;
}

.center40{
        margin-left: auto;
        margin-right: auto;
        width: 40%;
        border-collapse: collapse;
        padding: 12px;
    }
.center60{
        margin-left: auto;
        margin-right: auto;
        width: 60%;
        border: 2px;
   }
.center80{
    margin-left: auto;
    margin-right: auto;
    width: 80%;
    border: 2px;
}
/*tablas sin bordes*/
.center90{
    margin-left: auto;
    margin-right: auto;
    width: 90%;
    border:none;
border-width: 0;
}
   /*tablas con bordes*/
   table.border {
    border: 2px solid black;
    border-collapse: collapse;
  }
  .border th, .border td {
      border: 1px solid black;
    border-collapse: collapse;
  }