/* =====================
   Lux-Learning Design Tokens
   ===================== */
:root{
  --bb-blue: #3AB0FF;         /* Sky Blue */
  --bb-yellow: #FFD23F;       /* Sunflower */
  --bb-coral: #FF6B6B;        /* Accent */
  --bb-warm: #F4F4F4;         /* Warm Gray (light bg) */
  --bb-navy: #123B5A;         /* Primary text / dark UI */
  --bb-ink: #0F2437;          /* Headline ink */
  --bb-muted: #5B6B7C;        /* Muted text */
  --bb-white: #FFFFFF;
  --bb-radius: 16px;
  --bb-shadow: 0 10px 30px rgba(15,36,55,.12);
  --container: 1200px;
}

/* Base resets */
*,*::before,*::after{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0; font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji","Segoe UI Emoji";
  color: var(--bb-ink); background: #FAFCFF;
}
img{max-width:100%; display:block}
a{color:inherit; text-decoration:none}
.container{max-width: var(--container); margin:0 auto; padding:0 20px}
.btn{display:inline-flex; align-items:center; gap:.5rem; padding:.9rem 1.2rem; border-radius: 999px; font-weight:600; letter-spacing:.2px}
.btn.primary{background: var(--bb-blue); color:var(--bb-white)}
.btn.secondary{background: var(--bb-white); color:var(--bb-navy); border:1px solid #d5e7f7}
.pill{display:inline-block; padding:.35rem .7rem; border-radius: 999px; font-size:.8rem; font-weight:600}

/* Header */
header{position:sticky; top:0; z-index:50; background:rgba(255,255,255,.8); backdrop-filter:saturate(140%) blur(10px); border-bottom:1px solid #eef3f8}
.nav{display:flex; align-items:center; justify-content:space-between; padding:14px 0}
.brand{display:flex; align-items:center; gap:12px}
.logo{display:inline-flex; align-items:center}
.logo svg{height:36px; width:auto}
.brand .name{font-family: Montserrat, Inter, sans-serif; font-weight:800; font-size:1.25rem; letter-spacing:.2px; color:var(--bb-navy)}
nav ul{display:flex; gap:22px; list-style:none; margin:0; padding:0}
nav a{color:var(--bb-navy); font-weight:600}
.nav-cta{display:flex; align-items:center; gap:10px}
.hamburger{display:none; background:transparent; border:0; font-size:1.5rem}

/* Mobile nav */
@media (max-width: 860px){
  nav ul{display:none}
  .hamburger{display:block}
  .mobile-menu{display:none; position:absolute; left:0; right:0; top:60px; background:var(--bb-white); border-bottom:1px solid #eef3f8}
  .mobile-menu a{display:block; padding:14px 20px; border-top:1px solid #f2f5f8}
  .mobile-menu.open{display:block}
}

/* Hero */
.hero{padding: 64px 0 40px; background: linear-gradient(180deg, #EAF6FF 0%, #FFFFFF 65%)}
.hero .wrap{display:grid; grid-template-columns: 1.2fr .8fr; gap:40px; align-items:center}
.eyebrow{color:var(--bb-blue); font-weight:700; letter-spacing:.24em; text-transform:uppercase; font-size:.82rem}
h1{font-family: Montserrat, Inter, sans-serif; font-weight:800; font-size: clamp(2rem, 4vw, 3rem); line-height:1.1; margin:.4rem 0 1rem}
.tagline{font-size:1.15rem; color:var(--bb-muted); max-width:55ch}
.cta-row{margin-top:22px; display:flex; gap:12px; flex-wrap:wrap}
.hero-card{background:var(--bb-white); border:1px solid #e8eef5; padding:20px; border-radius: var(--bb-radius); box-shadow: var(--bb-shadow)}
.hero .art{justify-self:center}

/* Sections */
section{padding:56px 0}
.section-title{font-family: Montserrat, Inter, sans-serif; font-weight:800; font-size: clamp(1.6rem, 2.6vw, 2.2rem); margin:0 0 10px}
.section-lede{color:var(--bb-muted); max-width:60ch}

/* Filters */
.filters{display:flex; gap:10px; flex-wrap:wrap; margin-top:18px}
.filters .pill{background:#E6F3FF; color:#0E507A; border:1px solid #d5e7f7}
.filters .pill.active{background:var(--bb-blue); color:var(--bb-white); border-color: transparent}

/* Features Section */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.feature-card {
    background: var(--bb-white);
    border-radius: var(--bb-radius);
    padding: 30px;
    text-align: center;
    border: 1px solid #e8eef5;
    box-shadow: var(--bb-shadow);
    transition: transform 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--bb-blue), #2a9be8);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
}

.feature-icon i {
    font-size: 2rem;
    color: var(--bb-white);
}

.feature-card h3 {
    color: var(--bb-ink);
    margin-bottom: 15px;
    font-size: 1.3rem;
    font-weight: 700;
}

.feature-card p {
    color: var(--bb-muted);
    line-height: 1.6;
}

/* Quiz Section */
.quiz-section {
    background: var(--bb-warm);
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-header .section-lede {
    margin: 0 auto 30px;
}

.quiz-selection {
    background: var(--bb-white);
    border-radius: var(--bb-radius);
    padding: 40px;
    box-shadow: var(--bb-shadow);
    border: 1px solid #e8eef5;
    max-width: 800px;
    margin: 0 auto;
}

/* Grade Selector */
.grade-selector {
    text-align: center;
    margin-bottom: 40px;
}

.grade-selector h3 {
    margin-bottom: 20px;
    color: var(--bb-ink);
    font-size: 1.3rem;
    font-weight: 600;
}

.grade-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
}

.grade-btn {
    padding: 15px 30px;
    border: 2px solid var(--bb-blue);
    background: var(--bb-white);
    color: var(--bb-blue);
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.grade-btn.active,
.grade-btn:hover {
    background: var(--bb-blue);
    color: var(--bb-white);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(58, 176, 255, 0.4);
}

/* Units Grid */
.units-container h3 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--bb-ink);
    font-size: 1.3rem;
    font-weight: 600;
}

.units-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.unit-card {
    background: var(--bb-warm);
    border-radius: 14px;
    padding: 25px;
    border: 2px solid transparent;
    transition: all 0.3s ease;
    cursor: pointer;
}

.unit-card:hover {
    border-color: var(--bb-blue);
    transform: translateY(-5px);
    box-shadow: var(--bb-shadow);
}

.unit-card h4 {
    color: var(--bb-ink);
    margin-bottom: 10px;
    font-size: 1.3rem;
    font-weight: 600;
}

.unit-card p {
    color: var(--bb-muted);
    margin-bottom: 15px;
}

.topics-container {
    margin-top: 15px;
}

.topics-container p {
    font-weight: 600;
    color: var(--bb-ink);
    margin-bottom: 10px;
}

.topics-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.topic-btn {
    background: var(--bb-blue);
    color: var(--bb-white);
    border: none;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.topic-btn:hover {
    background: #2a9be8;
    transform: translateY(-2px);
    box-shadow: 0 3px 10px rgba(58, 176, 255, 0.3);
}

.student-info {
    text-align: center;
}

.student-info h3 {
    margin-bottom: 20px;
    color: var(--bb-ink);
    font-weight: 600;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 25px;
}

.form-group {
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--bb-ink);
}

.form-group input {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e1e5e9;
    border-radius: 10px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: var(--bb-blue);
    box-shadow: 0 0 0 3px rgba(58, 176, 255, 0.1);
}

/* Quiz Interface */
.quiz-interface {
    background: var(--bb-white);
    border-radius: var(--bb-radius);
    padding: 40px;
    box-shadow: var(--bb-shadow);
    margin: 40px 0;
    border: 1px solid #e8eef5;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #f0f0f0;
}

.quiz-info h2 {
    color: var(--bb-ink);
    margin-bottom: 5px;
    font-weight: 700;
}

.quiz-info p {
    color: var(--bb-muted);
}

.quiz-progress {
    text-align: right;
}

.progress-bar {
    width: 200px;
    height: 8px;
    background: #e1e5e9;
    border-radius: 4px;
    margin-bottom: 10px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--bb-blue), #2a9be8);
    transition: width 0.3s ease;
}

#question-counter {
    font-size: 0.9rem;
    color: var(--bb-muted);
}

.question-container {
    margin-bottom: 30px;
}

.question-display {
    background: var(--bb-warm);
    border-radius: 14px;
    padding: 30px;
    margin-bottom: 30px;
    font-size: 1.2rem;
    line-height: 1.8;
    color: var(--bb-ink);
    text-align: center;
    border: 2px solid #e1e5e9;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
}

/* Enhanced Mathematical Expression Styling */
.math-expression {
    font-family: 'Times New Roman', serif;
    font-size: 1.3rem;
    font-weight: 500;
    color: var(--bb-ink);
    margin: 10px 0;
    padding: 15px;
    background: var(--bb-white);
    border-radius: 10px;
    border: 2px solid #e8f4f8;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
/* === Lux-Learning numeric rendering fix (decimals, alignment) === */
.math-expression,
.answer-option {
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  font-variant-numeric: tabular-nums lining-nums;
  -webkit-font-feature-settings: "tnum" 1, "lnum" 1;
  -moz-font-feature-settings: "tnum" 1, "lnum" 1;
  font-feature-settings: "tnum" 1, "lnum" 1;
  letter-spacing: 0;
}
/* Ensure decimal dots aren't clipped and spacing stays even */
.math-expression { line-height: 1.5; }
.answer-option { line-height: 1.35; white-space: normal; }
/* === End numeric fix === */


.math-expression .operator {
    color: var(--bb-coral);
    font-weight: 600;
    margin: 0 8px;
}

.math-expression .parentheses {
    color: var(--bb-blue);
    font-weight: 600;
}

.math-expression .exponent {
    font-size: 0.8em;
    vertical-align: super;
    color: var(--bb-yellow);
    font-weight: 600;
}

.math-expression .fraction {
    display: inline-block;
    text-align: center;
    margin: 0 5px;
    vertical-align: middle;
}

.math-expression .fraction-numerator {
    display: block;
    border-bottom: 2px solid var(--bb-ink);
    padding: 0 5px;
    margin-bottom: 2px;
}

.math-expression .fraction-denominator {
    display: block;
    padding: 0 5px;
}

.math-expression .bracket {
    color: var(--bb-yellow);
    font-weight: 600;
}

.math-expression .number {
    color: var(--bb-blue);
    font-weight: 500;
}

/* Order of Operations Specific Styling */
.order-of-ops-question {
    background: linear-gradient(135deg, var(--bb-warm) 0%, #e9ecef 100%);
    border: 2px solid #dee2e6;
    border-radius: 14px;
    padding: 25px;
    margin: 15px 0;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
}

.order-of-ops-question .pemdas-hint {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 8px;
    padding: 10px 15px;
    margin-bottom: 15px;
    font-size: 0.9rem;
    color: #856404;
    text-align: center;
    font-weight: 500;
}

.order-of-ops-question .pemdas-hint strong {
    color: var(--bb-coral);
    font-weight: 700;
}

/* Enhanced Fraction Styling */
.fraction {
    display: inline-block;
    text-align: center;
    vertical-align: middle;
    margin: 0 3px;
    position: relative;
}

.fraction-line {
    display: block;
    border-bottom: 2px solid var(--bb-ink);
    margin: 2px 0;
    min-width: 20px;
}

.answer-option .fraction {
    font-size: 1.1rem;
    margin: 0 5px;
}

.answer-option .fraction-line {
    border-bottom-width: 1px;
}

.answer-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 15px;
    margin-bottom: 30px;
}

.answer-option {
    background: var(--bb-white);
    border: 2px solid #e1e5e9;
    border-radius: 12px;
    padding: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--bb-ink);
    position: relative;
    overflow: hidden;
}

.answer-option:hover {
    border-color: var(--bb-blue);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(58, 176, 255, 0.2);
}

.answer-option.selected {
    background: var(--bb-blue);
    color: var(--bb-white);
    border-color: var(--bb-blue);
}

.answer-option.correct {
    background: #d4edda;
    border-color: #28a745;
    color: #155724;
}

.answer-option.incorrect {
    background: #f8d7da;
    border-color: #dc3545;
    color: #721c24;
}

.question-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 30px;
}

.nav-btn {
    background: var(--bb-blue);
    color: var(--bb-white);
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-btn:hover:not(:disabled) {
    background: #2a9be8;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(58, 176, 255, 0.3);
}

.nav-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.submit-btn {
    background: linear-gradient(135deg, #28a745, #20c997);
    color: var(--bb-white);
    border: none;
    padding: 15px 30px;
    border-radius: 25px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 0 auto;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(40, 167, 69, 0.3);
}

/* Results Screen */
.results-screen {
    background: var(--bb-white);
    border-radius: var(--bb-radius);
    padding: 40px;
    box-shadow: var(--bb-shadow);
    margin: 40px 0;
    border: 1px solid #e8eef5;
}

.results-header {
    text-align: center;
    margin-bottom: 40px;
}

.results-header h2 {
    color: var(--bb-ink);
    margin-bottom: 20px;
}

.score-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.score-circle {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--bb-blue), #2a9be8);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--bb-white);
    font-size: 1.5rem;
    font-weight: 700;
    box-shadow: 0 10px 25px rgba(58, 176, 255, 0.3);
}

.score-display p {
    font-size: 1.2rem;
    color: var(--bb-muted);
    font-weight: 600;
}

.results-details {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-bottom: 30px;
}

.results-summary {
    background: var(--bb-warm);
    border-radius: 14px;
    padding: 25px;
}

.results-summary h3 {
    margin-bottom: 20px;
    color: var(--bb-ink);
    font-weight: 600;
}

.summary-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1rem;
    color: var(--bb-muted);
}

.stat-item i.correct {
    color: #28a745;
}

.stat-item i.incorrect {
    color: #dc3545;
}

.question-review h3 {
    margin-bottom: 20px;
    color: var(--bb-ink);
    font-weight: 600;
}

.review-list {
    max-height: 400px;
    overflow-y: auto;
}

.review-item {
    background: var(--bb-white);
    border-radius: 10px;
    padding: 15px;
    margin-bottom: 10px;
    border-left: 4px solid #e1e5e9;
}

.review-item.correct {
    border-left-color: #28a745;
}

.review-item.incorrect {
    border-left-color: #dc3545;
}

.review-question {
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--bb-ink);
}

.review-answer {
    font-size: 0.9rem;
    color: var(--bb-muted);
    margin-bottom: 5px;
}

.review-status {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
}

.review-status.correct {
    color: #28a745;
}

.review-status.incorrect {
    color: #dc3545;
}

.results-actions {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 30px;
    flex-wrap: wrap;
}

.export-btn,
.new-quiz-btn {
    padding: 12px 25px;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.export-btn {
    background: #17a2b8;
    color: var(--bb-white);
    border: none;
}

.export-btn:hover {
    background: #138496;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(23, 162, 184, 0.3);
}

.new-quiz-btn {
    background: var(--bb-blue);
    color: var(--bb-white);
    border: none;
}

.new-quiz-btn:hover {
    background: #2a9be8;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(58, 176, 255, 0.3);
}

.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.95);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--bb-blue);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

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

.loading-screen p {
    font-size: 1.1rem;
    color: var(--bb-muted);
    font-weight: 500;
}

.hidden {
    display: none !important;
}

/* Testimonial & CTA */
.testimonials{background: #0f2f49; color:#E9F4FF; border-top: 6px solid var(--bb-yellow)}
.quote{font-size:1.15rem}
.newsletter{background: var(--bb-warm)}
.newsletter .box{background:var(--bb-white); border:1px solid #e8eef5; border-radius: var(--bb-radius); padding:20px; box-shadow: var(--bb-shadow)}

/* Footer */
footer{background:#0f2f49; color:#cfe0f2}
footer a{color:#cfe0f2}
.footer-grid{display:grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap:20px}

/* Responsive Design */
@media (max-width: 980px){
  .hero .wrap{grid-template-columns: 1fr}
  .footer-grid{grid-template-columns: 1fr 1fr}
  .form-row{grid-template-columns: 1fr}
}

@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .quiz-setup,
    .quiz-interface,
    .results-screen {
        padding: 25px;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .grade-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .units-grid {
        grid-template-columns: 1fr;
    }
    
    .quiz-header {
        flex-direction: column;
        gap: 20px;
    }
    
    .results-details {
        grid-template-columns: 1fr;
    }
    
    .question-navigation {
        flex-direction: column;
        gap: 15px;
    }
    
    .results-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .answer-options {
        grid-template-columns: 1fr;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 620px){
  .footer-grid{grid-template-columns: 1fr}
}

/* LaTeX Fraction Styling */
.latex-fraction {
    font-family: 'Times New Roman', serif;
    font-size: 1.2em;
    line-height: 1.6;
    margin: 15px 0;
    padding: 20px;
    background: linear-gradient(135deg, var(--bb-warm) 0%, #e9ecef 100%);
    border-radius: 10px;
    border-left: 5px solid #28a745;
    box-shadow: 0 3px 6px rgba(0,0,0,0.1);
    text-align: center;
}

.latex-fraction .question-text {
    font-weight: 600;
    color: var(--bb-ink);
    margin-bottom: 10px;
}

.latex-fraction .mathjax {
    font-size: 1.3em;
    color: var(--bb-ink);
    margin: 10px 0;
}

/* Enhanced fraction display */
.fraction-display {
    background: linear-gradient(135deg, #e8f5e8 0%, #d4edda 100%);
    border: 2px solid #28a745;
    border-radius: 12px;
    padding: 20px;
    margin: 15px 0;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.fraction-display .fraction-title {
    font-weight: bold;
    color: #155724;
    margin-bottom: 10px;
    text-align: center;
}

.fraction-display .fraction-content {
    text-align: center;
    font-size: 1.4em;
    color: var(--bb-ink);
} 

/* Numeric span for perfect decimal alignment */
.num {
  font-variant-numeric: tabular-nums lining-nums;
  -webkit-font-feature-settings: "tnum" 1, "lnum" 1;
  -moz-font-feature-settings: "tnum" 1, "lnum" 1;
  font-feature-settings: "tnum" 1, "lnum" 1;
}