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

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    scroll-behavior: smooth;
}

body {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 100vh;
    font-family: Arial, sans-serif;
    background: linear-gradient(135deg, #a27ec7, #2575fc);
    transition: background-color 0.5s ease, color 0.5s ease;
    overflow-x: hidden;
}

body.dark-mode {
    background: #121212;
    color: #ffffff;
}

.container {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 20px;
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    width: 90%;
    max-width: 600px;
    margin: 20px auto;
    transition: background-color 0.5s ease, color 0.5s ease, transform 0.5s ease;
    position: relative;
}

body.dark-mode .container {
    background-color: #1e1e1e;
    color: #ffffff;
}

h1 {
    text-align: center;
    margin-bottom: 20px;
    color: #333;
    animation: fadeIn 1s ease-in-out;
}

body.dark-mode h1 {
    color: #ffffff;
}

.course {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
    opacity: 0;
    animation: fadeInSlideDown 0.5s ease forwards;
}
@keyframes fadeInSlideDown {
    0% { opacity: 0; transform: translateY(-20px); }
    100% { opacity: 1; transform: translateY(0); }
}

input, select {
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    flex: 1;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

body.dark-mode input, body.dark-mode select {
    background-color: #333;
    color: #ffffff;
    border-color: #555;
}

.credits {
    width: 80px;
}

button {
    padding: 8px 16px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

button:hover {
    background-color: #0056b3;
    transform: scale(1.05);
}

.remove-btn {
    background-color: #dc3545;
}

.remove-btn:hover {
    background-color: #b02a37;
}

#add-course {
    background-color: #28a745;
    margin-right: 10px;
}

#add-course:hover {
    background-color: #218838;
}

.controls {
    display: flex;
    gap: 10px;
    margin-top: 20px;
    flex-wrap: wrap;
}

#result {
    margin-top: 20px;
    text-align: center;
    animation: fadeIn 1s ease-in-out;
}

#gpa-value {
    color: #007bff;
    font-weight: bold;
    transition: color 0.3s ease;
}

.copyright {
    text-align: center;
    padding: 10px;
    background-color: rgba(255, 255, 255, 0.8);
    color: #333;
    font-size: 14px;
    width: 100%;
    transition: background-color 0.5s ease, color 0.5s ease;
}

body.dark-mode .copyright {
    background-color: rgba(0, 0, 0, 0.8);
    color: #fff;
}

@keyframes fadeIn {
    0% { opacity: 0; }
    100% { opacity: 1; }
}

@keyframes popUp {
    0% { transform: scale(0); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

#result h2 {
    animation: popUp 0.5s ease-in-out;
}

/* Mobile responsiveness */
@media (max-width: 500px) {
    .container {
        padding: 15px;
    }
    h1 {
        font-size: 1.5rem;
    }
    #result h2 {
        font-size: 1.2rem;
    }
    .course {
        flex-direction: column;
        align-items: stretch;
        gap: 8px;
    }

    .course input, .course button {
        width: 100%;
        box-sizing: border-box;
    }

    .credits {
        width: 100%;
    }

    .controls {
        flex-direction: column;
        gap: 8px;
    }

    button {
        padding: 10px;
        font-size: 14px;
    }

    input, select {
        padding: 6px;
        font-size: 14px;
    }

    .copyright {
        font-size: 12px;
        padding: 8px;
    }
}