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

/* Body Styling */
body {
    font-family: Arial, sans-serif;
    background: linear-gradient(to right, #0066cc, #00cc66);
    color: #fff;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    padding-top: 60px; /* Space for the fixed navbar */
}

/* Navbar Styling */
.navbar {
    width: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
    display: flex;
    justify-content: center;
    padding: 10px 0;
    transition: top 0.3s; /* Smooth transition for hiding/showing */
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3); /* Subtle shadow for depth */
    border-bottom: 2px solid rgba(255, 255, 255, 0.2); /* Subtle border */
}

/* Navbar List Styling */
.navbar ul {
    list-style: none;
    display: flex;
    flex-wrap: nowrap; /* Prevent wrapping */
    justify-content: space-evenly; /* Equal space between items */
    width: 100%;
    padding: 0;
    margin: 0;
}

/* Navbar List Item Styling */
.navbar li {
    flex-grow: 1; /* Ensure each item grows equally */
    text-align: center;
}

/* Navbar Links Styling */
.navbar a {
    color: #fff;
    text-decoration: none;
    padding: 10px 20px;
    display: block;
    font-size: 1.1em;
    font-weight: 600;
    border-radius: 5px;
    transition: background-color 0.3s, transform 0.3s; /* Smooth transitions */
}

/* Navbar Link Hover Effects */
.navbar a:hover {
    background-color: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px); /* Slight lift effect */
}

/* Navbar Link Active State */
.navbar a.active {
    background-color: rgba(255, 255, 255, 0.4);
    transform: translateY(-2px);
}

/* Calculator Container Styling */
.calculator-container {
    display: none;
    width: 100%;
    max-width: 400px;
    margin: 80px 0 20px; /* Adjusted margin to account for the fixed navbar */
    padding: 20px;
    background-color: rgba(0, 0, 0, 0.8);
    border-radius: 10px;
    text-align: center;
}

/* Show active calculator container */
.calculator-container.active {
    display: block;
}

/* Display Styling */
.display {
    width: 100%;
    padding: 10px;
    margin-bottom: 20px;
    border-radius: 5px;
    border: none;
    font-size: 1.2em;
    text-align: right;
}

/* Buttons Grid Styling */
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

/* Button Styling */
.button {
    padding: 15px;
    font-size: 1.2em;
    border: none;
    border-radius: 5px;
    background-color: #333;
    color: #fff;
    cursor: pointer;
    transition: background-color 0.3s;
}

/* Button Hover Effects */
.button:hover {
    background-color: #555;
}

/* Operator Button Styling */
.operator {
    background-color: #ff9800;
}

.operator:hover {
    background-color: #e68900;
}

/* Equal Button Styling */
.equal {
    background-color: #4caf50;
    grid-column: span 2;
}

.equal:hover {
    background-color: #3e8e41;
}

/* Zero Button Styling */
.zero {
    grid-column: span 2;
}

/* Input Group Styling */
.input-group {
    margin-bottom: 10px;
    text-align: left;
}

.input-group label {
    display: block;
    margin-bottom: 5px;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 10px;
    border-radius: 5px;
    border: none;
    font-size: 1em;
}

/* Result Styling */
.result {
    margin-top: 20px;
    font-size: 1.2em;
    color: #ffeb3b;
}

/* Responsive Design for iPhone SE (320px wide) */
@media (max-width: 320px) {
    .navbar ul {
        flex-wrap: wrap;
        justify-content: center; /* Center items on very small screens */
    }

    .navbar a {
        padding: 8px;
        font-size: 0.9em;
    }

    .calculator-container {
        margin: 50px 0 20px; /* Further adjusted margin for smaller screens */
        padding: 10px;
    }

    .display {
        font-size: 0.9em;
    }

    .buttons {
        grid-template-columns: repeat(3, 1fr);
    }

    .button {
        padding: 10px;
        font-size: 0.9em;
    }
}

/* Responsive Design for iPhone 13 (390px wide) */
@media (max-width: 390px) {
    .navbar ul {
        flex-wrap: nowrap;
        justify-content: space-evenly; /* Equal spacing for iPhone 13 */
    }

    .navbar a {
        padding: 10px;
        font-size: 1em;
    }

    .calculator-container {
        margin: 70px 0 20px; /* Adjusted margin for iPhone 13 */
        padding: 15px;
    }

    .display {
        font-size: 1em;
    }

    .buttons {
        grid-template-columns: repeat(4, 1fr);
    }

    .button {
        padding: 12px;
        font-size: 1em;
    }
}

/* Responsive Design for Galaxy S20 (360px wide) */
@media (max-width: 360px) {
    .navbar ul {
        flex-wrap: nowrap;
        justify-content: space-evenly; /* Equal spacing for Galaxy S20 */
    }

    .navbar a {
        padding: 10px;
        font-size: 1em;
    }

    .calculator-container {
        margin: 60px 0 20px; /* Adjusted margin for Galaxy S20 */
        padding: 15px;
    }

    .display {
        font-size: 1em;
    }

    .buttons {
        grid-template-columns: repeat(3, 1fr);
    }

    .button {
        padding: 12px;
        font-size: 1em;
    }
}