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

body {
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #89f7fe, #66a6ff);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    background: #fff;
    padding: 30px 40px;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
    text-align: center;
    width: 90%;
    max-width: 400px;
    transition: transform 0.3s;
}

.container:hover {
    transform: translateY(-5px);
}

h2 {
    color: #333;
    margin-bottom: 25px;
    font-size: 24px;
}

input {
    display: block;
    width: 80%;
    margin: 10px auto;
    padding: 12px;
    border-radius: 10px;
    border: 1px solid #ccc;
    font-size: 16px;
    transition: border 0.3s, box-shadow 0.3s;
}

input:focus {
    border-color: #4CAF50;
    box-shadow: 0 0 8px rgba(76, 175, 80, 0.5);
    outline: none;
}

button {
    padding: 12px 20px;
    margin: 5px;
    border-radius: 10px;
    border: none;
    background-color: #4CAF50;
    color: white;
    font-size: 14px;
    cursor: pointer;
    transition: background 0.3s, transform 0.2s;
}

button:hover {
    background-color: #45a049;
    transform: scale(1.05);
}

#result {
    margin-top: 20px;
    font-size: 18px;
    font-weight: bold;
    white-space: pre-line;
    padding: 10px;
    border-radius: 10px;
}

.grade-A\+ { color: #2e7d32; }  /* Dark Green */
.grade-A  { color: #388e3c; }
.grade-B  { color: #f9a825; }  /* Amber */
.grade-C  { color: #f57c00; }  /* Orange */
.grade-D  { color: #e65100; }  /* Dark Orange */
.grade-F  { color: #b71c1c; }  /* Red */

@media (max-width: 480px) {
    .container {
        padding: 20px;
    }

    input {
        width: 90%;
        padding: 10px;
    }

    button {
        padding: 10px 15px;
        font-size: 13px;
    }

    h2 {
        font-size: 20px;
    }

    #result {
        font-size: 16px;
    }
}
.grade-A+, .grade-A, .grade-B, .grade-C, .grade-D, .grade-F {
    font-size: 40px !important;
}