style.css

/* Basic Reset & Body */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: Arial, Helvetica, sans-serif; /* Common sans-serif font */
    line-height: 1.6;
    color: #333;
    background-color: #f4f4f4; /* Light gray background */
    padding: 20px 0; /* Add padding top/bottom */
}

.container {
    max-width: 960px; /* Adjust max width as needed */
    margin: 20px auto; /* Center the container */
    background-color: #fff; /* White background for content */
    padding: 30px;
    border: 1px solid #ddd; /* Subtle border */
    box-shadow: 0 2px 5px rgba(0,0,0,0.1); /* Subtle shadow */
}

/* Headings */
h1 {
    font-size: 1.8em; /* Adjust size */
    font-weight: bold;
    margin-bottom: 20px;
    color: #222;
    line-height: 1.3;
}

h2 {
    font-size: 1.4em;
    font-weight: bold;
    text-align: center;
    margin-top: 35px;
    margin-bottom: 25px;
    color: #444;
}

h3 { /* Diagram Titles */
    font-size: 1.1em;
    margin-bottom: 15px;
    color: #555;
    font-weight: bold;
}

/* Paragraphs */
p {
    margin-bottom: 16px;
    text-align: left; /* Or 'justify' if preferred */
}

p strong {
    font-weight: bold;
    color: #000; /* Make bold text black */
}

/* Button Bar */
.button-bar {
    display: flex;
    flex-wrap: wrap; /* Allow buttons to wrap on smaller screens */
    gap: 10px; /* Spacing between buttons */
    margin-top: 25px;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid #eee; /* Separator line */
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 8px 15px;
    color: #fff; /* Default text color */
    text-decoration: none;
    border: none;
    border-radius: 4px;
    font-size: 0.9em;
    transition: opacity 0.3s ease; /* Smooth hover effect */
    text-align: center;
    cursor: pointer;
}

.btn:hover {
    opacity: 0.85; /* Slightly fade on hover */
}

/* Specific Button Colors (approximated from image) */
.btn-blue { background-color: #007bff; } /* Standard blue */
.btn-yellow { background-color: #ffc107; color: #333; } /* Yellow with dark text */
.btn-blue-dark { background-color: #0056b3; } /* Darker blue */
.btn-green { background-color: #28a745; } /* Standard green */


/* Diagram Section */
.diagram-section {
    display: flex;
    justify-content: center; /* Center items horizontally */
    align-items: flex-start; /* Align boxes at the top */
    gap: 20px; /* Space between diagram boxes/arrow */
    margin-top: 20px;
    margin-bottom: 20px;
    flex-wrap: wrap; /* Allow wrapping */
}

.diagram-box {
    border: 1px solid #ccc;
    border-radius: 8px;
    padding: 20px;
    background-color: #f9f9f9; /* Light background for boxes */
    text-align: center;
    flex: 1; /* Allow boxes to take up available space */
    min-width: 250px; /* Minimum width before wrapping */
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.diagram-box img {
    max-width: 100%;
    height: auto; /* Maintain aspect ratio */
    display: block; /* Remove extra space below image */
    margin: 10px auto 0; /* Center image if it's narrower */
    border: 1px solid #eee; /* Optional border around images */
}

.arrow {
    font-size: 2.5em; /* Make arrow larger */
    color: #6c757d; /* Gray color */
    align-self: center; /* Center arrow vertically between boxes */
    padding: 0 10px; /* Add horizontal spacing */
    flex-shrink: 0; /* Prevent arrow from shrinking */
    font-weight: bold;
}

/* Specific styling for the downstream box */
.downstream-box {
    /* If it needs to span full width when wrapped, adjust parent or use specific width */
     margin-top: 10px; /* Add space if it's below */
     flex-basis: 80%; /* Example: make it wider if needed */
     max-width: 600px; /* Limit its max width */
     margin-left: auto; /* Center it if flex-basis is less than 100% */
     margin-right: auto;
}

.placeholder-content {
    border: 1px dashed #ccc;
    padding: 30px;
    color: #999;
    font-style: italic;
    margin-top: 10px;
}

/* Basic Responsive Adjustments */
@media (max-width: 768px) {
    .container {
        padding: 20px;
    }
    h1 {
        font-size: 1.6em;
    }
    .button-bar {
        justify-content: center; /* Center buttons */
    }
     /* Stack diagrams vertically */
    .diagram-section {
         flex-direction: column;
         align-items: center;
     }
     .arrow {
         transform: rotate(90deg); /* Rotate arrow */
         margin: 15px 0; /* Adjust margin for vertical layout */
     }
     .diagram-box {
         width: 90%; /* Adjust width for stacked view */
         max-width: 450px;
         min-width: unset;
         flex-basis: auto; /* Reset flex basis */
     }
     .downstream-box{
         flex-basis: auto; /* Reset flex basis */
         width: 90%;
     }
}

 @media (max-width: 480px) {
     h1 {
         font-size: 1.4em;
     }
     .btn {
         width: 100%; /* Make buttons full width */
         margin-bottom: 5px;
     }
     .button-bar {
         gap: 5px;
     }
     body {
         padding: 10px 0;
     }
     .container {
         padding: 15px;
     }
 }