/* General Styles */
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; /* Modern font */
    margin: 0;
    padding: 0;
    background-color: #f8f9fa; /* Light background */
    color: #343a40; /* Darker text color */
    transition: background-color 0.3s ease, color 0.3s ease;
    line-height: 1.6; /* Improved readability */
}

header, footer {
    background-color: #343a40; /* Dark header/footer */
    color: #fff;
    padding: 1em 0; /* Reduced padding */
    text-align: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1); /* Subtle shadow */
}

main {
    padding: 2em; /* Increased padding */
    max-width: 90%; /* Limit content width */
    margin: 0 auto; /* Center content */
}

/* Navigation */
nav {
    margin-bottom: 1.5em; /* Increased spacing */
}

nav a {
    color: #fff;
    text-decoration: none;
    padding: 0.75em 1.25em; /* Increased padding */
    border-radius: 0.25em;
    background-color: #6c757d; /* Gray background */
    transition: background-color 0.3s ease;
    font-weight: 500;
}

nav a:hover {
    background-color: #5a6268;
}

/* Spreadsheet Styles */
.spreadsheet-container {
    overflow-x: auto;
    border-radius: 0.5em;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.15); /* Stronger shadow */
    background-color: #fff;
}

#spreadsheet {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 2em; /* Increased spacing */
}

#spreadsheet th, #spreadsheet td {
    border: 1px solid #e9ecef;
    padding: 0.5em; /* Reduced padding */
    text-align: center;
    min-width: 60px;
    font-size: 0.95em;
}

#spreadsheet th {
    background-color: #f0f0f0; /* Light gray header */
    font-weight: 600; /* Bold header text */
    position: sticky;
    top: 0;
    z-index: 2;
}

#spreadsheet input[type="text"] {
    width: 100%;
    box-sizing: border-box;
    border: 1px solid #ced4da; /* Lighter input border */
    padding: 0.5em;
    text-align: center;
    border-radius: 0.25em;
    font-size: 0.95em;
}

/* Controls */
.controls {
    text-align: center;
    margin-bottom: 2em; /* Increased spacing */
}

.controls button, .controls a {
    display: inline-block;
    margin: 0 1em;
    padding: 0.75em 1.5em;
    border: none;
    border-radius: 0.25em;
    background-color: #007bff;
    color: #fff;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.1s ease;
    font-weight: 500;
    font-size: 1em;
}

.controls a:first-child {
    margin-right: 1em;
}

.controls button:hover, .controls a:hover {
    background-color: #0056b3;
    transform: translateY(-2px); /* Subtle lift effect */
}

.controls .support-button {
    background-color: #28a745;
}

.controls .support-button:hover {
    background-color: #218838;
    transform: translateY(-2px);
}

/* Responsive Design */
@media (max-width: 768px) {
    #spreadsheet th, #spreadsheet td {
        padding: 0.5em;
        font-size: 0.9em;
    }
    .controls button, .controls a {
        padding: 0.6em 1.2em;
        font-size: 0.9em;
    }
    main {
        max-width: 95%;
    }
}