/* --- CSS Variables from Calculator --- */
:root {
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #212529;
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --secondary-color: #6c757d;
    --secondary-hover: #5a6268;
    --danger-color: #dc3545;
    --danger-hover: #c82333;
    --border-color: #dee2e6;
    --info-bg: #eef1f5;
    --shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
    --border-radius: 8px;
}

/* --- General Body Styling (from Ribbon) --- */
body {
    font-family: 'Inter', sans-serif, system-ui;
    background-color: var(--bg-color); /* Use theme background */
    color: var(--text-color);
    margin: 0;
    font-size: 15px;
    overflow-x: hidden; /* Prevent horizontal scroll */
}

/* --- Styles for the H1 Title Block (MODIFIED) --- */
h1 {
    /* Box model styles to match other cards */
    max-width: 900px;
    margin: 2rem auto 1rem auto; /* Center the box and add margin */
    padding: 1.5rem;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);

    /* Flexbox layout for internal content */
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 1rem;

    /* Font styles */
    color: var(--text-color);
    font-size: 1.7em;
}

/* Wrapper for title and copyright notice */
.h1-title-group {
    flex-shrink: 0;
}

/* Main title text */
.h1-title {
     display: block;
     color: #343a40;
}

/* Copyright notice below title */
.h1-copyright {
    font-size: 0.5em;
    font-weight: normal;
    color: #555;
    margin-top: 5px;
}
.h1-copyright a {
    color: var(--primary-color);
    text-decoration: none;
}
.h1-copyright a:hover {
    text-decoration: underline;
}

/* Container for info items on the right */
.h1-info {
    display: flex;
    flex-wrap: wrap;
    gap: 10px 20px;
    font-size: 0.4em; /* Font size reduced */
    text-align: center;
    align-items: flex-start;
}

.info-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.info-label {
    font-weight: bold;
    color: #444;
    margin-bottom: 4px;
    text-transform: uppercase;
    font-size: 0.85em;
    letter-spacing: 0.5px;
}

.info-content a, .info-content span {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 1.1em;
}
.info-content a:hover {
    color: var(--primary-hover);
}
.h1-info a i {
    font-size: 2em;
    transition: transform 0.2s ease-in-out;
}
.h1-info a:hover i {
    transform: scale(1.1);
}

/* --- Main content container --- */
.main-content {
    max-width: 900px;
    background-color: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    margin: 0 auto 2rem auto; /* Adjusted top margin */
}

/* Page description below title ribbon */
.page-description {
    text-align: center;
    font-size: 1.05em;
    color: var(--secondary-color);
    margin: 0 auto 2rem auto;
}


/* --- Styles for Calculator components --- */

/* Info Section & Collapsible Styles */
.info-section {
    background-color: var(--info-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 2rem;
    padding: 0 1.5rem;
}

.collapsible-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    padding: 1rem 0;
}

h2 {
    margin: 0 0 1rem 0;
    font-size: 1.25rem;
    color: var(--primary-color);
}

.collapsible-header h2 {
     margin: 0;
}

.toggle-icon {
    font-size: 1.5rem;
    color: var(--secondary-color);
    transition: transform 0.3s ease-in-out;
}
.toggle-icon.expanded {
    transform: rotate(90deg);
}

.collapsible-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease-in-out;
}

.info-content-inner {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 2rem;
    align-items: center;
    padding: 1.5rem 0;
    border-top: 1px solid var(--border-color);
}

.info-diagram {
    display: flex;
    align-items: center;
    justify-content: center;
}

.info-formulas p { margin: 0.5rem 0; }
.info-formulas ul { margin-top: 0.5rem; padding-left: 1.5rem; }
.info-formulas li { margin-bottom: 0.25rem; }
.info-formulas code {
    background-color: #d6dbdf;
    padding: 0.2em 0.4em;
    border-radius: 4px;
    font-family: 'Courier New', Courier, monospace;
}

/* Main Calculator Styles */
.input-section h2 {
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1.5rem;
}

.system-params {
     grid-template-columns: minmax(150px, 1fr);
     max-width: 250px;
}

.fiber-section {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    background-color: #fdfdff;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

.section-header h3 {
    margin: 0;
    color: var(--primary-color);
}

.input-group {
    display: flex;
    flex-direction: column;
}

label {
    margin-bottom: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
}

.info-icon {
    display: inline-block;
    width: 16px;
    height: 16px;
    background-color: var(--secondary-color);
    color: white;
    border-radius: 50%;
    text-align: center;
    font-size: 11px;
    line-height: 16px;
    font-style: normal;
    font-weight: bold;
    cursor: help;
    margin-left: 8px;
    user-select: none;
}

input[type="number"] {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.2s, box-shadow 0.2s;
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

input[readonly] {
    background-color: #e9ecef;
    cursor: not-allowed;
}

.button-container {
    text-align: center;
    margin: 2rem 0;
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

button {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 0.9rem 2rem;
    font-size: 1.1rem;
    font-weight: bold;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover { background-color: var(--secondary-hover); }
button.primary { background-color: var(--primary-color); }
button.primary:hover { background-color: var(--primary-hover); }
button.remove-btn {
    background-color: var(--danger-color);
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}
button.remove-btn:hover { background-color: var(--danger-hover); }

/* Results Section */
.results-section {
    background-color: #e9f5ff;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    border: 1px solid #bde0fe;
}
.results-section h2 {
    margin-top: 0;
}

#results-list .result-item {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem 0;
    font-size: 1.1rem;
}

#results-list .result-item + .result-item {
    border-top: 1px dashed var(--border-color);
}

.result-total {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 2px solid var(--primary-color);
    font-weight: bold;
    font-size: 1.3rem;
    display: flex;
    justify-content: space-between;
}

.hidden { display: none; }

/* Responsive adjustments */
@media (max-width: 768px) {
    .info-content-inner {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    .info-diagram {
        max-width: 300px;
        margin: 0 auto;
    }
}