@import url('https://fonts.googleapis.com/css2?family=Rubik&display=swap');
        
        :root {
            --primary-color: #021a3d;
            --secondary-color: #f5f7fa;
            --text-color: #333;
            --light-text-color: #777;
            --border-color: #dce1e6;
            --background-color: #ffffff;
            --shadow-color: rgba(0, 0, 0, 0.1);
        }

        body {
            font-family: 'Rubik', sans-serif;
            background-color: var(--secondary-color);
            color: var(--text-color);
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            margin: 0;
            padding: 20px;
            box-sizing: border-box;
        }

        .calculator-container {
            background-color: var(--background-color);
            padding: 30px 40px;
            border-radius: 12px;
            box-shadow: 0 10px 25px var(--shadow-color);
            width: 100%;
            max-width: 700px;
            text-align: center;
        }

        h1 {
            color: var(--primary-color);
            margin-top: 0;
            margin-bottom: 10px;
        }

        .description {
            color: var(--light-text-color);
            margin-bottom: 30px;
            font-size: 0.9em; /* Subtítulo menor */
        }

        .input-group {
            margin-bottom: 20px;
            text-align: left;
        }

        .input-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 400;
            font-size: 0.9em;
            color: #555;
        }

        input[type="month"],
        input[type="text"],
        input[type="date"] {
            width: 100%;
            padding: 12px;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            font-family: 'Poppins', sans-serif;
            font-size: 1em;
            box-sizing: border-box;
            transition: border-color 0.3s, box-shadow 0.3s;
        }

        input:focus {
            outline: none;
            border-color: var(--primary-color);
            box-shadow: 0 0 0 3px rgba(240, 78, 98, 0.2);
        }

        input:disabled {
            background-color: #e9ecef;
            cursor: not-allowed;
        }

        .date-group {
            display: flex;
            gap: 20px;
            justify-content: space-between;
        }

        .date-group .input-group {
            flex: 1;
        }

        .result-container {
            background-color: var(--secondary-color);
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
            border: 1px solid var(--border-color);
        }

        .result-container h2 {
            margin: 0 0 10px;
            font-size: 1.1em;
            font-weight: 400;
            color: var(--light-text-color);
        }

         .btn-back {
          margin: 15px auto;
          border: none;
          background-color: #021a3d;
          color: #fff;
          border-radius: 5px;
          padding: 10px 15px;
       }

        #result-display {
            font-size: 2.5em;
            font-weight: 600;
            color: var(--primary-color);
            display: flex;
            justify-content: center;
            align-items: center;
        }

        #result-display .currency {
            font-size: 0.6em;
            margin-right: 5px;
            align-self: flex-start;
            margin-top: 10px;
        }

        #calculation-details {
            margin-top: 15px;
            font-size: 0.8em;
            color: var(--light-text-color);
            min-height: 1.2em; 
        }