@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@500;700&family=Open+Sans:wght@400;600&display=swap');

.controls-explanation-card {
    background-color: var(--color-background-card);
    border-left: 4px solid var(--color-accent-primary);
    box-shadow: var(--card-box-shadow);
    border-radius: var(--card-border-radius);
    padding: var(--space-md) var(--space-lg);
    margin: var(--space-lg) 0;
}

.controls-explanation-card > p {
    font-weight: 600;
    color: var(--color-accent-primary-darker);
    margin-bottom: var(--space-sm);
}

.controls-explanation-card ul {
    list-style: none;
    padding-left: 0;
    margin-bottom: 0;
}

.controls-explanation-card li {
    position: relative;
    padding-left: 1.25rem;
    margin-bottom: var(--space-sm);
}

.controls-explanation-card li::before {
    content: "\2022"; /* Bullet */
    color: var(--color-accent-primary);
    position: absolute;
    left: 0;
    top: 0.4rem;
    font-size: 0.75rem;
}

*, *::before, *::after {
    box-sizing: border-box;
}

:root {
    /* Light Theme Color Palette (from guide_style.md) */
    --color-background-page: #F8F9FA;      /* Very Light Gray */
    --color-background-card: #FFFFFF;       /* White */
    --color-text-primary: #212529;        /* Almost Black/Very Dark Gray */
    --color-text-secondary: #6C757D;      /* Medium Gray */
    --color-accent-primary: #17A2B8;       /* Teal/Cyan */
    --color-accent-primary-darker: #138496; /* Darker Teal */
    --color-accent-secondary-plot-loss: #E83E8C; /* Pink/Magenta */
    --color-accent-secondary-plot-phi: #28A745;  /* Green */
    --color-accent-tertiary-particles: #FFC107; /* Soft Orange/Amber for particles */
    --color-border: #DEE2E6;              /* Light Gray */
    --color-text-on-accent: #FFFFFF;      /* White */
    --color-slider-track: #E9ECEF;        /* Light Gray */
    --color-hero-background: linear-gradient(to bottom right, #E0F7FA, #F8F9FA); /* Very Light Cyan to Very Light Gray gradient */

    /* Typography */
    --font-family-headings: 'Montserrat', sans-serif;
    --font-family-body: 'Open Sans', sans-serif;
    --font-size-base: 1rem; /* 16px */
    --line-height-base: 1.6;
    --line-height-headings: 1.4; /* Adjusted from 1.3 to 1.4 as per guide range */

    /* Layout & Spacing (using guide's naming convention) */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-xxl: 48px;

    /* Components */
    --card-border-radius: 8px; /* As per guide */
    --card-box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05); /* As per guide */
    --nav-height: 70px; /* Adjusted for potentially larger text/padding */
    --button-border-radius: 6px; /* Guide: 4px or 6px, choosing 6px */
}

body {
    font-family: var(--font-family-body);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--color-text-primary);
    background-color: var(--color-background-page) !important;
    margin: 0;
    /*padding-top: var(--nav-height); /* Space for the fixed main navigation */
}

a {
    color: var(--color-accent-primary) !important;
    text-decoration: none; /* Optional: removes underline */
    transition: color 0.2s ease;
}

a:hover, a:focus {
    color: var(--color-accent-primary-darker);
    text-decoration: underline; /* Optional: adds underline on hover */
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-lg) 0;
}

/* Generic Re-usable Heading Style for Sections */
.section-heading {
    font: 700 1.75rem/1.3 var(--font-family-headings);
    color: var(--color-accent-primary-darker);
    margin-bottom: var(--space-sm);
    letter-spacing: 0.2px;
    position: relative;
}
.section-heading::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -0.3em;
    width: 3rem;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent-primary), var(--color-accent-primary-darker));
}

/* --- Section Specific Styling --- */
.section-text-content {
    max-width: 100%;
    overflow-x: hidden; /* Prevent this container itself from overflowing */
}


/* Hero Section Styling */
.hero-section {
    background: var(--color-hero-background);
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: var(--space-xxl) var(--space-lg);
    min-height: 60vh; /* Larger splash */
    margin-bottom: var(--space-xl);
    overflow: hidden; /* Hide overflowing content */
}

/* Particle Canvas inside hero */
#hero-particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0; /* Ensure particles are behind text and other foreground elements */
    pointer-events: none;
    /* background-color: red; Diagnostic style removed */
}

/* Soft fade-out to merge particle canvas into page background */
.hero-section::after {
    content: '';
    position: absolute;
    inset: auto 0 0 0; /* full width bottom strip */
    height: 160px;
    background: linear-gradient(to bottom, transparent 0%, var(--color-background-page) 90%);
    pointer-events: none;
    z-index: 1; /* sits above canvas but below hero text */
}

.hero-meta {
    text-align: center;
    position: relative;
    z-index: 2; /* above canvas */
}

.paper-title {
    font: 700 2.25rem/1.2 var(--font-family-headings);
    color: var(--color-accent-primary-darker);
    margin: 0 0 var(--space-md);
}
.author-details {
    display: flex;
    justify-content: center;
    align-items: flex-start; /* Align blocks at the top if text wraps differently */
    gap: var(--space-lg); /* Space between author blocks */
    margin-bottom: var(--space-xs);
}

.author-block {
    text-align: center;
}

.author-name {
    font-weight: 600; /* Slightly bolder for names */
    margin: 0 0 var(--space-xxs); /* Minimal space between name and affiliation */
}

.author-affiliation {
    font-size: 0.9rem; /* Slightly smaller for affiliation */
    margin: 0;
}

.paper-journal, /* Keep styling for journal, remove old paper-authors/affil */
.paper-authors, /* Retain for potential future single-line use, but not primary for this layout */
.paper-affil { /* Retain for potential future single-line use, but not primary for this layout */
    margin: 0;
    color: var(--color-text-secondary);
    font-size: 0.95rem;
}
/* .paper-authors { margin-bottom: var(--space-xs); } */ /* Handled by author-details margin */
/* .paper-affil   { margin-bottom: var(--space-xs); } */ /* Handled by author-details margin */

/* legacy selector remains for backwards compatibility */
.hero-content {
    position: relative;
    z-index: 2;
}

.hero-wave {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 120px;
    pointer-events: none;
    z-index: 1;
}

.hero-wave path {
    animation: waveShift 12s linear infinite;
    transform-origin: center;
}

@keyframes waveShift {
    0% {
        transform: translateX(0);
    }
    100% {
        transform: translateX(-50%);
    }
}

.hero-section .hero-title, /* Assuming h1 or a class for hero title */
.hero-section h1 {
    font-family: var(--font-family-headings);
    font-size: 2.8rem; /* ~45px, guide: ~2.8rem - 3rem */
    font-weight: 700;
    color: var(--color-text-primary);
    line-height: var(--line-height-headings);
    margin-bottom: var(--space-sm);
}

.hero-section .hero-title .accent-text,
.hero-section h1 .accent-text {
    color: var(--color-accent-primary);
}

.hero-section .hero-subtitle {
    font-size: 1.1rem;
    color: var(--color-text-secondary);
    line-height: var(--line-height-base);
}

/* Main Navigation */
.main-navigation {
    background-color: var(--color-background-card); /* Using card color for nav */
    height: var(--nav-height);
    padding: 0 var(--space-lg); /* Increased padding */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05); /* Softer shadow */
    display: flex;
    align-items: center;
    justify-content: center; 
}

.main-navigation ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
}

.main-navigation li {
    margin: 0 var(--space-md);
}

.main-navigation a {
    font-family: var(--font-family-headings);
    color: var(--color-text-secondary); /* Secondary text for non-active */
    text-decoration: none;
    font-weight: 500; /* Montserrat medium */
    font-size: 0.9rem;
    padding: var(--space-sm) 0;
    transition: color 0.2s ease, border-color 0.2s ease;
    border-bottom: 2px solid transparent;
}

.main-navigation a:hover,
.main-navigation a:focus {
    color: var(--color-accent-primary);
}

.main-navigation a.active-link {
    color: var(--color-accent-primary);
    font-weight: 700; /* Montserrat bold */
    border-bottom: 2px solid var(--color-accent-primary);
}

/* Permanently hide the main navigation menu */
.main-navigation {
    display: none !important;
}

/* Code and LaTeX Containers */
.code-block {
    background-color: var(--color-background-code);
    border-radius: var(--card-border-radius);
    padding: var(--space-lg);
    margin-bottom: var(--space-lg);
    overflow-x: auto;
}

.code-block pre {
    margin: 0;
}

.code-block code {
    font-family: var(--font-family-monospace);
    font-size: 0.9em;
}

.latex-equation {
    text-align: center;
    padding-top: var(--space-lg);
    padding-left: 0;
    padding-right: 0;
    padding-bottom: 10px; /* For scrollbar spacing */
    margin-bottom: var(--space-lg);
    overflow-x: auto;   /* Add horizontal scrollbar if content overflows */
    overflow-y: hidden; /* Prevent vertical scrollbar */
}

/* Content Sections (Cards) */
.content-section {
    margin-bottom: var(--space-xl); /* guide: space-lg or space-xl */
    padding: var(--space-lg);    /* guide: space-lg or space-xl */
    background-color: var(--color-background-card);
    border-radius: var(--card-border-radius);
    box-shadow: var(--card-box-shadow);
    border: 1px solid var(--color-border);
}

/* Intro Section (Section Zero) */
.intro-section {
    background-color: var(--color-background-page);
    border: none;
    box-shadow: none;
    text-align: center;
    padding: calc(var(--space-xl) * 1.5) var(--space-lg);
}

.intro-section h2 {
    font-size: 2rem; /* Larger heading */
    margin-bottom: var(--space-lg);
    color: var(--color-accent-primary);
}

.intro-section p {
    font-size: 1.05rem;
    line-height: 1.6;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.intro-section ul {
    list-style: disc inside;
    max-width: 800px;
    margin: var(--space-md) auto;
    padding-left: 0;
    text-align: left;
}

.intro-section li {
    margin-bottom: var(--space-sm);
}

.section-supertitle {
    font-size: 0.8rem; /* 12.8px, guide: ~13px */
    font-weight: 600; /* Open Sans Semibold */
    color: var(--color-text-secondary);
    text-transform: uppercase;
    margin-bottom: var(--space-xs);
    display: block;
}

.content-section h2, .section-title {
    font-family: var(--font-family-headings);
    font-size: 1.75rem; /* 28px, as per guide */
    font-weight: 700; /* Montserrat Bold */
    color: var(--color-accent-primary);
    margin-top: 0;
    margin-bottom: var(--space-lg);
    line-height: var(--line-height-headings);
}

/* === New Typographic & Content Elements (Added 2025-07-01) === */

/* Section Introduction Paragraph */
.section-intro {
    font-size: 1.1rem;
    /* Slightly larger than base */
    line-height: 1.7;
    color: var(--color-text-secondary);
    /* Softer color for intro */
    margin-bottom: var(--space-lg); 
    /* Optimal line length */
}

/* Sub-Topic Heading (e.g., for h3 or h4 level topics within a section) */
.sub-topic-heading {
    font-family: var(--font-family-headings);
    font-size: 1.3rem; /* Between base and section title */
    font-weight: 600; /* Montserrat semibold or similar */
    color: var(--color-text-primary);
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-xs);
    border-bottom: 1px solid var(--color-border);
    position: relative;
    max-width: 75ch;
}

/* Informational Callout (for tips, notes, definitions) */
.info-callout {
    background-color: #f0f7fa; /* Very light blue/cyan, derived from hero gradient */
    border-left: 4px solid var(--color-accent-primary);
    padding: var(--space-md); 
    border-radius: var(--card-border-radius); /* Consistent with other cards */
    font-size: 0.95rem;
    max-width: 75ch;
    height: fit-content; /* Ensure height wraps content */
    align-self: start;   /* Prevent stretching in flex/grid containers */
}
.info-callout p:last-child {
    margin-bottom: 0;
}
.info-callout strong, .info-callout b { /* Emphasize titles within callouts */
    color: var(--color-accent-primary-darker);
    font-weight: 600;
}

/* Refined Estimate Card */
.estimate-card { /* Assuming this class is on a div wrapping the estimates */
    background-color: var(--color-background-card);
    padding: var(--space-lg);
    border-radius: var(--card-border-radius);
    box-shadow: var(--card-box-shadow);
    border: 1px solid var(--color-border);
    margin: var(--space-lg) 0;
    max-width: 60ch; /* Cards might be narrower */
}
.estimate-card .card-title { /* Optional title for the card */
    font-family: var(--font-family-headings);
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--color-border);
}
.est-line { /* For individual key-value lines within the estimate card */
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    padding: var(--space-sm) 0;
    border-bottom: 1px dashed var(--color-border);
    font-size: 0.95rem;
}
.est-line:last-child {
    border-bottom: none;
}
.est-line .est-label {
    color: var(--color-text-secondary);
    margin-right: var(--space-md);
    flex-shrink: 0;
}
.est-line .est-value {
    font-weight: 600;
    color: var(--color-text-primary);
    text-align: right;
    flex-grow: 1;
    word-break: break-all; /* Prevent long values from breaking layout */
}
.est-line .b-matrix-pill {
    font-weight: normal; /* Override potential inherited bold from .est-value */
}

/* Plot Caption */
.plot-caption {
    font-size: 0.875rem; /* 14px */
    color: var(--color-text-secondary);
    text-align: center;
    margin-top: var(--space-sm);
    margin-bottom: var(--space-lg);
    line-height: 1.5;
    max-width: 70ch;
    margin-left: auto;
    margin-right: auto;
}
.plot-caption strong, .plot-caption b {
    font-weight: 600;
    color: var(--color-text-primary);
}

/* Refined .b-matrix-pill (was in paragraph_util.css) */
.b-matrix-pill {
  display: inline-block;
  background: #e9ecef; /* Using --color-slider-track for a neutral light gray */
  padding: 0.1em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
  line-height: 1.2;
  color: var(--color-text-primary);
  margin: 0 0.1em;
  vertical-align: baseline;
}

/* General prose styling improvements within content sections */
.content-section > p, /* Direct children paragraphs */
.content-section > ul,
.content-section > ol,
.content-section > .info-callout > p, /* Paragraphs inside callouts */
.content-section > .section-intro /* Ensure section intro also adheres */
 {
    max-width: 75ch; /* Optimal line length for readability */
    /* If the content-section is not centered, add margin: auto for these text blocks */
    /* margin-left: auto; margin-right: auto; */ /* This might be too aggressive globally */
}

.content-section p,
.content-section ul,
.content-section ol {
    margin-bottom: var(--space-md); /* Consistent paragraph/list spacing */
}
.content-section ul, .content-section ol {
    padding-left: var(--space-lg); /* Indent lists */
}
.content-section li {
    margin-bottom: var(--space-sm); /* Consistent list item spacing */
}

/* Ensure Katex rendered math also respects text color */
.katex {
    color: var(--color-text-primary);
}


/* Controls Area */
.controls-placeholder {
    height: 1px;
    margin-top: -1px;
}
.controls-container {
    background-color: var(--color-background-card);
    padding: var(--space-lg);
    border-radius: var(--card-border-radius);
    margin-bottom: var(--space-lg);
    box-shadow: var(--card-box-shadow);
    border: 1px solid var(--color-border);
    position: relative;
}

.controls-container.sticky-menu {
    position: fixed;
    background-color: var(--color-background-card);
    z-index: 900;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1); 
    border-radius: var(--card-border-radius);
    border: 1px solid var(--color-border);
}

.controls-row {
    display: flex;
    flex-wrap: nowrap; /* Default: prevent wrapping */
    gap: var(--space-lg);
    align-items: center; /* Better vertical alignment */ 
    justify-content: space-between; /* Distribute items evenly */
    overflow-x: auto; /* Allow horizontal scrolling if needed */
    padding-bottom: var(--space-sm); /* Add space for scrollbar */
}

.control-item {
    display: flex; /* Keep children inline */
    align-items: center; 
    min-width: fit-content; /* Prevent items from shrinking too much */
    flex-wrap: nowrap; /* Prevent wrapping inside control */
}

.control-item label {
    font-size: 0.875rem; /* 14px, as per guide */
    font-weight: 600; /* Open Sans Semibold */
    color: var(--color-text-primary);
}

.control-item input[type="number"],
.control-item input[type="text"],
.control-item select {
    padding: var(--space-sm) var(--space-md);
    border: 1px solid var(--color-border);
    background-color: var(--color-background-card);
    color: var(--color-text-primary);
    border-radius: var(--button-border-radius); /* Using button radius for consistency */
    font-family: var(--font-family-body);
    font-size: 0.9rem;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.control-item input[type="number"]:focus,
.control-item input[type="text"]:focus,
.control-item select:focus {
    outline: none;
    border-color: var(--color-accent-primary);
    box-shadow: 0 0 0 2px rgba(var(--color-accent-primary), 0.25);
}

/* Sliders */
.control-item input[type="range"] {
    width: 180px; /* Increased width */
    height: 8px; /* Track height guide: 6-8px */
    -webkit-appearance: none;
    appearance: none;
    background: var(--color-slider-track);
    border-radius: 4px;
    cursor: pointer;
}

.control-item input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px; /* Thumb diameter guide: 16-18px */
    height: 18px;
    background: var(--color-accent-primary);
    border-radius: 50%;
    border: 2px solid var(--color-background-card); /* Optional: border to lift thumb */
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.control-item input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--color-accent-primary);
    border-radius: 50%;
    border: 2px solid var(--color-background-card);
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
    cursor: pointer;
}

.control-item output {
    font-size: 0.875rem; /* 14px, as per guide */
    font-weight: 400; /* Open Sans Regular */
    color: var(--color-text-secondary); 
    min-width: 30px; /* Ensure space for values */
    text-align: right;
}

/* Toggle Switch for B₀ Mode */
.mode-switch-control { /* Container for the B0 label and the toggle */
    display: flex;
    align-items: center; /* Vertically align B0 label and toggle */ 
}

.mode-prefix-label { /* The "B0=" label */
    font-weight: 600; /* Match other control labels */
    font-size: 0.875rem; /* Match other control labels */
    color: var(--color-text-primary);
    margin-right: var(--space-xs);
}

.mode-switch-toggle {
    position: relative;
    display: inline-block;
    width: 260px; /* Increased width to fit 'Non-Recursive' */
    height: 34px;
}

.mode-switch-toggle input {
    opacity: 0;
    width: 0;
    height: 0;
}

.mode-switch-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-background-card);
    border: 1px solid var(--color-border);
    transition: .4s;
    border-radius: 22px;
    width: 100%; /* Fills the toggle container and preserves rounded ends */
    overflow: hidden; /* Clip inner highlight for clean rounding */
    display: flex;
    align-items: center;
    /* justify-content: space-between; /* Removed */
    /* padding: 0 10px; /* Removed */
}

.mode-switch-slider:before {
    position: absolute;
    content: "";
    height: calc(100% - 4px); /* Full height minus border of parent */
    width: 126px; /* 50% width minus inner gaps */
    left: 2px; /* Offset for border */
    bottom: 2px; /* Offset for border */
    background-color: var(--color-accent-primary);
    transition: .4s;
    border-radius: 22px; /* Match outer slider radius for rounded corners */
    z-index: 1;
}

.mode-switch-toggle input:checked + .mode-switch-slider:before {
    transform: translateX(130px);
}

.mode-switch-toggle .mode-label {
    white-space: nowrap; /* Prevent line breaks */
    color: var(--color-text-secondary); /* Default color for non-active labels */
    font-size: 0.875rem;
    font-weight: 600;
    z-index: 2;
    position: relative;
    width: 50%; /* Changed from 85px to 50% */
    text-align: center;
    transition: color 0.4s;
}

.mode-switch-toggle input:checked + .mode-switch-slider .non-recursive-label,
.mode-switch-toggle input:not(:checked) + .mode-switch-slider .recursive-label {
    color: var(--color-text-on-accent); /* Active label color */
}

.mode-switch-control { 
    align-items: center; 
}

/* Mode Switch (styling for a select element, can be enhanced with custom control later) */
.mode-switch select {
    /* Uses general input styling above */
    font-weight: 600; /* Semibold for Open Sans */
}

/* Plot Container */
.plot-container {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-lg);
}

.plots-grid {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-lg);
}

.plot-area {
    flex-basis: calc(50% - (var(--space-lg) / 2));
    min-width: 300px;
    height: 400px; /* Or make aspect-ratio based if desired */
    background-color: var(--color-background-card);  
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.plot-area .plot-title {
    font-family: var(--font-family-headings);
    font-size: 0.9rem; /* guide: 0.875rem - 0.9rem */
    font-weight: 500; /* Montserrat Medium */
    color: var(--color-text-primary);
    margin-bottom: var(--space-sm);
}

/* Ensure Plotly's internal elements respect the .plot-area dimensions */
.plot-area .js-plotly-plot,
.plot-area .plot-container.plotly,
.plot-area .svg-container {
    width: 100% !important;
    height: 100% !important;
}

.plot-area .main-svg {
    width: 100% !important;
    height: 100% !important;
}

/* Footer */
.footer {
    text-align: center;
    padding: var(--space-lg) 0; /* guide: space-md or space-lg */
    margin-top: var(--space-xl);
    font-size: 0.8rem; /* 12.8px, guide: ~13px */
    color: var(--color-text-secondary);
    background-color: var(--color-background-page); /* As per guide */
    border-top: 1px solid var(--color-border);
}

/* Utility classes */
.text-center {
    text-align: center;
}

/* Buttons */
.btn {
    font-family: var(--font-family-body); /* Guide: Open Sans */
    padding: 10px 20px; /* guide: ~10px 20px */
    font-size: 0.9rem;
    font-weight: 600; /* Open Sans Semibold */
    border-radius: var(--button-border-radius);
    border: 1px solid transparent;
    cursor: pointer;
    transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, opacity 0.2s ease, transform 0.1s ease;
    text-decoration: none;
    display: inline-block;
}
.btn-primary {
    background-color: var(--color-accent-primary);
    color: var(--color-text-on-accent);
    border-color: var(--color-accent-primary);
}
.btn-primary:hover, .btn-primary:focus {
    background-color: var(--color-accent-primary-darker);
    border-color: var(--color-accent-primary-darker);
    color: var(--color-text-on-accent);
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-accent-primary);
    border: 1px solid var(--color-accent-primary);
}
.btn-secondary:hover, .btn-secondary:focus {
    background-color: var(--color-accent-primary);
    color: var(--color-text-on-accent);
    border-color: var(--color-accent-primary);
}

/* New Data Button - accent style */
.btn.new-data-button {
    background-color: var(--color-accent-primary);
    color: var(--color-text-on-accent);
    border: 1px solid var(--color-accent-primary);
    padding: 8px 18px; /* slightly tighter than generic */
    font-size: 0.9rem;
    font-weight: 600;
    border-radius: var(--button-border-radius);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    transition: background-color 0.2s ease, transform 0.1s ease, box-shadow 0.2s ease;
}

.btn.new-data-button:hover,
.btn.new-data-button:focus {
    background-color: var(--color-accent-primary-darker);
    border-color: var(--color-accent-primary-darker);
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    text-decoration: none;
}

.btn.new-data-button:active {
    transform: translateY(0);
    box-shadow: none;
}

/* MathJax specific styling if needed */
.MathJax {
    color: var(--color-text-primary) !important; /* Ensure MathJax inherits primary text color */
}

/* Responsive adjustments */
/* Controls toggle button */
.controls-toggle-btn { 
    top: 12px; /* Adjusted for better alignment */
    right: 12px; /* Adjusted for better alignment */
    width: 32px;
    height: 32px;
    border-radius: var(--button-border-radius); /* Rounded square */
    background-color: transparent;
    border: 1px solid var(--color-border);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    padding: 0;
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.controls-toggle-btn:hover,
.controls-toggle-btn:focus {
    background-color: var(--color-background-card-hover);
    border-color: var(--color-border-strong); /* Or a slightly darker border */
    outline: none; /* Remove default focus outline if custom is applied */
}

.toggle-icon {
    position: relative;
    width: 16px; /* Adjusted width */
    height: 2px;
    background-color: var(--color-text-primary);
    transition: all 0.3s ease;
}

.toggle-icon::before,
.toggle-icon::after {
    content: '';
    position: absolute;
    left: 0; /* Ensure alignment */
    width: 16px; /* Adjusted width */
    height: 2px;
    background-color: var(--color-text-primary);
    transition: all 0.3s ease;
}

.toggle-icon::before {
    transform: translateY(-5px); /* Adjusted spacing */
}

.toggle-icon::after {
    transform: translateY(5px); /* Adjusted spacing */
}

.controls-toggle-btn.active .toggle-icon {
    background-color: transparent;
}

.controls-toggle-btn.active .toggle-icon::before {
    transform: rotate(45deg);
}

.controls-toggle-btn.active .toggle-icon::after {
    transform: rotate(-45deg);
}

/* Collapsed state */
.controls-container.collapsed .controls-row {
    display: none;
}

/* Main Navigation Mobile Styles */
.main-nav-toggle {
    display: none; /* Hidden by default, shown in media query */
    background: transparent;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    z-index: 1001; /* Above nav content */
}

.main-nav-toggle-icon {
    display: block;
    position: relative;
    width: 24px; /* Hamburger icon width */
    height: 2px; /* Thickness of the lines */
    background-color: var(--color-text-primary);
    transition: all 0.2s ease-in-out;
}

.main-nav-toggle-icon::before,
.main-nav-toggle-icon::after {
    content: '';
    position: absolute;
    left: 0;
    width: 100%;
    height: 2px; /* Thickness of the lines */
    background-color: var(--color-text-primary);
    transition: all 0.2s ease-in-out;
}

.main-nav-toggle-icon::before {
    transform: translateY(-7px); /* Space between lines */
}

.main-nav-toggle-icon::after {
    transform: translateY(7px); /* Space between lines */
}

/* Active state for hamburger (X) */
.main-nav-toggle.active .main-nav-toggle-icon {
    background-color: transparent; /* Middle line disappears */
}

.main-nav-toggle.active .main-nav-toggle-icon::before {
    transform: translateY(0) rotate(45deg);
}

.main-nav-toggle.active .main-nav-toggle-icon::after {
    transform: translateY(0) rotate(-45deg);
}

/* Ensure controls toggle button is visible and controls are collapsed by default on small screens, and handle overflow for controls-row on larger screens */
@media (min-width: 769px) {
    .controls-toggle-btn {
        display: none !important;
    }
    .controls-container.collapsed .controls-row {
        display: flex;
    }
    .controls-row {
        flex-wrap: wrap; /* Allow wrapping on large screens */
        overflow-x: visible; /* No need for horizontal scroll when wrapping */
        padding-bottom: 0; /* Remove scrollbar padding */
    }

}

/* Estimator comparison card styles */
.comparison-card{
  display:flex;
  gap:var(--space-lg);
  padding:var(--space-md);
  background:var(--color-background-card);
  border:1px solid var(--color-border);
  border-radius:var(--card-border-radius);
  box-shadow:var(--card-box-shadow);
  flex-wrap:wrap;
  margin-bottom: var(--space-md);
}
.comparison-col{
  flex:1 1 200px;
  text-align:center;
}
.comp-heading{
  font:700 0.9rem/1 var(--font-family-headings);
  color:var(--color-accent-primary-darker);
  margin-bottom:var(--space-xs);
}
.comp-matrix{
  font-size:1rem;
  font-family:'Lato', serif;
}
.comparison-card:hover .comp-matrix{
  background:rgba(0,173,181,0.05);   /* faint teal */
}
.comparison-discussion {
  border-left:4px solid var(--color-primary);
  background: var(--color-white);
  padding: var(--space-md);
  margin-top: var(--space-sm);
  font-size:0.95rem;
  box-shadow: var(--card-box-shadow);
  border-radius: var(--card-border-radius);
}

.comp-discussion-heading {
  font: 700 0.95rem/1 var(--font-family-headings);
  color: var(--color-primary);
  margin-bottom: var(--space-xs);
}

.comparison-discussion-row {
  margin-bottom: var(--space-md);
}

@media (max-width: 768px) {
    .comparison-card {
        flex-direction: column;
        gap: var(--space-md);
    }
    .comparison-col {
        flex: 0 0 auto; /* avoid tall empty space when stacked */
    }

    
    .main-navigation {
        padding: 0 var(--space-md);
        justify-content: space-between; /* Logo on left, hamburger on right */
    }

    .main-navigation .main-nav-toggle {
        display: block; /* Show hamburger on mobile */
    }

    /* Styles for the navigation list (ul) in mobile view */
    .main-navigation ul {
        display: none; /* Hide nav links by default on mobile */
        flex-direction: column;
        position: absolute;
        top: var(--nav-height); /* Position below the nav bar */
        left: 0;
        width: 100%;
        background-color: var(--color-background-card); /* Or var(--color-background) */
        padding: var(--space-md) 0;
        box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        z-index: 1000; /* Ensure it's above content below */
    }

    /* When the navigation is open, show the list */
    .main-navigation.nav-open ul {
        display: flex;
    }

    /* Styles for list items (li) in mobile view */
    .main-navigation li {
        margin: 0; /* Remove default margins */
        width: 100%;
        text-align: center;
    }

    /* Styles for links (a) in mobile view */
    .main-navigation a {
        display: block;
        padding: var(--space-md) var(--space-lg);
        border-bottom: 1px solid var(--color-border-light); /* Separator for links */
        width: 100%; /* Make links take full width */
        /* Inherit general link styles from above, or redefine as needed */
    }
    
    /* Hover, focus, and active states for links in mobile view */
    .main-navigation a:hover,
    .main-navigation a:focus,
    .main-navigation a.active-link {
        background-color: var(--color-background-card-hover);
        color: var(--color-accent-primary);
        border-bottom-color: var(--color-accent-primary); /* Highlight active/hovered link's border */
    }

    .controls-container.sticky-menu {
        top: var(--nav-height);
    }
    .controls-container {
        padding: var(--space-sm);
    }
    .controls-row { 
        align-items: stretch;
        flex-wrap: wrap;
        overflow: hidden;
    } 
    .control-item input[type="range"] {
        width: 180px; /* Preserve compact width on small screens */
    }

/* === Layout Enhancements (2025-06-15) === */
/* 1. Constrain overall section width and center page content */
.content-section {
    max-width: 960px;               /* readable line length */
    margin: 3rem auto;              /* vertical rhythm + center */
    padding:   1.25rem;             /* horizontal breathing room */

    /* 2-column grid: controls left (fixed), content right (auto) */
    display: grid;
    grid-template-columns: 280px 1fr;
    column-gap: 24px;
}

/* Full-width heading spans both columns */
.content-section > h2 {
    grid-column: 1 / -1;
}

/* Controls in column 1 */
.content-section > .controls-container {
    grid-column: 1;
}

/* Everything after controls flows into column 2 */
.content-section > .controls-container ~ * {
    grid-column: 2;
}

/* Mobile: collapse to single column */
@media (max-width: 900px) {
    .content-section {
        grid-template-columns: 1fr;
    }
    .content-section > .controls-container {
        grid-column: 1;
    }
    .content-section > .controls-container ~ * {
        grid-column: 1;
    }
}

/* 3. Prose typography for better readability */
.prose,
.content-section p {
    max-width: 65ch;    /* ~65 characters per line */
    line-height: 1.65;  /* relaxed line spacing */
    margin-bottom: 1rem;
}

/* Keep cards and plots from stretching full width in grid */
.plot-container.card,
.latex-output-container.card,
.plot-area {
    max-width: 100%;
}

    .plot-area {
        flex-basis: 100%;
    }
    .hero-section .hero-title,
    .hero-section h1 {
        font-size: 2.2rem;
    }
    .content-section h2, .section-title {
        font-size: 1.5rem;
    }
}

/* Loading Overlay Styles */
#loading-overlay {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--space-xxl) 0; /* Add some padding when it's inside main-content */
    min-height: 30vh; /* Give it some minimum height to stabilize content */
    opacity: 1;
    visibility: visible;
    transition: opacity var(--transition-speed-normal) ease-out, visibility var(--transition-speed-normal) ease-out;
}

#loading-overlay.hidden {
    opacity: 0;
    visibility: hidden;
    display: none !important; /* Ensure it's removed from layout when hidden */
}

.loading-spinner {
    border: 8px solid var(--color-slider-track); /* Light gray for track */
    border-top: 8px solid var(--color-accent-primary); /* Accent for spinner */
    border-radius: 50%;
    width: 60px;
    height: 60px;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Initial visibility for navigation and footer */
.main-navigation,
.footer {
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed-slow) ease-in-out;
}

/* Ensure main-content itself is visible by default */
#main-content {
    opacity: 1;
    visibility: visible;
}

/* --- Content Loading Transition --- */

/* Initially, hide all content sections that are NOT section-zero.
   We use max-height for a smooth collapse/expand transition. */
.content-section:not(#section-zero) {
    opacity: 0;
    visibility: hidden;
    max-height: 0;
    overflow: hidden;
    margin-top: 0;
    margin-bottom: 0;
    padding-top: 0;
    padding-bottom: 0;
    border-width: 0;
    transition: all 0.5s ease-in-out;
}

/* Section zero is always visible and does not transition. */
#section-zero {
    opacity: 1;
    visibility: visible;
}

/* When the main content area is marked as 'loaded', reveal the sections. */
#main-content.loaded .content-section:not(#section-zero) {
    opacity: 1;
    visibility: visible;
    max-height: 5000px; /* Large enough to not clip content */
    /* Restore original spacing from .content-section rule */
    margin: 3rem auto;
    padding: 1.25rem;
    border-width: 1px;
}

/* Also handle the fade-in for nav and footer */
.main-navigation,
.footer {
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.5s ease-in-out 0.2s; /* Delay slightly */
}

.main-navigation.loaded,
.footer.loaded {
    opacity: 1;
    visibility: visible;
}