/* =====================================
   RESET
===================================== */

*{
    margin:0;
    padding:0;
    box-sizing:border-box;
}

html{
    scroll-behavior:smooth;
}

body{

    font-family:
    'Poppins',
    sans-serif;

    background:#f8fafc;

    color:#0f172a;

    line-height:1.7;
}

/* =====================================
   LINKS
===================================== */

a{

    text-decoration:none;

    color:inherit;
}

/* =====================================
   HEADER
===================================== */

.lesson-header{

    position:sticky;

    top:0;

    z-index:1000;

    background:#ffffff;

    border-bottom:1px solid #e5e7eb;

    display:flex;

    justify-content:space-between;

    align-items:center;

    padding:14px 18px;
}

.logo{

    display:flex;

    align-items:center;
}

.logo img{

    height:46px;

    width:auto;

    display:block;
}

/* =====================================
   LEARNING HUB BUTTON
===================================== */

.resource-toggle{

    border:none;

    background:#f1f5f9;

    color:#0f172a;

    padding:10px 14px;

    border-radius:10px;

    font-size:0.9rem;

    font-weight:600;

    cursor:pointer;

    transition:0.3s ease;
}

.resource-toggle:hover{

    background:#e2e8f0;
}

/* =====================================
   RESOURCE MENU
===================================== */

.resource-menu{

    display:none;

    background:#ffffff;

    border-bottom:1px solid #e5e7eb;
}

.resource-menu.active{

    display:block;
}

.resource-menu a{

    display:block;

    padding:16px 20px;

    border-bottom:1px solid #f1f5f9;

    color:#334155;

    font-weight:500;
}

.resource-menu a.active{

    background:#f8fafc;

    font-weight:600;
}

/* =====================================
   HERO
===================================== */

.lesson-hero{

    padding:50px 20px 35px;

    text-align:center;
}

.engine-tag{

    display:inline-block;

    background:#ffffff;

    border:1px solid #e5e7eb;

    padding:8px 16px;

    border-radius:999px;

    font-size:0.85rem;

    font-weight:600;

    color:#475569;

    margin-bottom:18px;
}

.lesson-hero h1{

    font-size:2rem;

    font-weight:700;

    color:#0f172a;

    margin-bottom:10px;
}

.lesson-hero p{

    color:#64748b;

    font-size:1rem;
}

/* =====================================
   SECTION TITLE
===================================== */

.section-title{

    text-align:center;

    margin-bottom:25px;
}

.section-title h2{

    font-size:1.7rem;

    color:#0f172a;

    margin-bottom:8px;
}

.section-title p{

    color:#64748b;
}

/* =====================================
   CHAPTER DNA
===================================== */

.chapter-dna{

    padding:0 20px 35px;
}

.dna-card{

    background:#ffffff;

    border:1px solid #e5e7eb;

    border-radius:18px;

    padding:28px;

    text-align:center;
}

.dna-card h2{

    margin-bottom:12px;

    color:#0f172a;
}

.dna-card p{

    color:#475569;

    max-width:700px;

    margin:auto;
}

/* =====================================
   LEARNING HUB
===================================== */

.learning-hub{

    padding:0 20px 35px;
}

.hub-grid{

    display:grid;

    grid-template-columns:1fr;

    gap:16px;
}

.hub-card{

    background:#ffffff;

    border:1px solid #e5e7eb;

    border-radius:18px;

    padding:22px;

    transition:0.3s ease;
}

.hub-card:hover{

    transform:translateY(-2px);
}

.hub-card h3{

    color:#0f172a;

    margin-bottom:8px;

    font-size:1.05rem;
}

.hub-card p{

    color:#64748b;

    font-size:0.92rem;
}
/* =====================================
   TABLES
===================================== */

.table-container{

    overflow-x:auto;

    margin:20px 0;
}

.table-container table{

    width:100%;

    border-collapse:collapse;

    min-width:500px;

    background:#ffffff;
}

.table-container th{

    background:#f8fafc;

    color:#0f172a;

    text-align:left;

    padding:14px;

    border:1px solid #e5e7eb;

    font-weight:600;
}

.table-container td{

    padding:14px;

    border:1px solid #e5e7eb;

    color:#475569;
}

/* =====================================
   DECISION TREE
===================================== */

.decision-tree{

    background:#f8fafc;

    border:1px solid #e2e8f0;

    border-radius:14px;

    padding:22px;

    text-align:center;

    color:#0f172a;

    font-weight:600;

    line-height:2;
}
/* =====================================
   DOWNLOAD
===================================== */

.download-section{

    padding:0 20px 35px;
}

.download-btn{

    display:block;

    width:100%;

    text-align:center;

    background:#0f172a;

    color:#ffffff;

    padding:16px;

    border-radius:14px;

    font-weight:600;

    transition:0.3s ease;
}

.download-btn:hover{

    background:#1e293b;
}

/* =====================================
   CONTENT
===================================== */

.lesson-content{

    padding:0 20px 35px;
}

.content-card{

    background:#ffffff;

    border:1px solid #e5e7eb;

    border-radius:18px;

    padding:24px;

    margin-bottom:18px;
}

.content-card h2{

    color:#0f172a;

    margin-bottom:12px;

    font-size:1.3rem;
}

.content-card p{

    color:#475569;
}

.content-card ul{

    padding-left:20px;
}

.content-card li{

    margin-bottom:8px;

    color:#475569;
}

.content-card img{

    width:100%;

    display:block;

    border-radius:12px;

    margin-top:12px;
}
/* =====================================
   RECALL ENGINE COMPONENTS
===================================== */

/* Section Intro */

.section-intro{

    color:#64748b;

    margin-bottom:18px;
}

/* Formula Section */

.formula-section h3{

    color:#0f172a;

    margin-top:24px;

    margin-bottom:12px;

    font-size:1.15rem;
}

/* Formula Card */

.formula-card{

    background:#f8fafc;

    border:1px solid #e2e8f0;

    border-radius:14px;

    padding:18px;

    margin:16px 0;
}

.formula-card h4{

    color:#0f172a;

    font-size:1rem;

    font-weight:600;

    margin-bottom:10px;
}

.formula-card p{

    color:#64748b;

    margin-top:10px;
}
@media(max-width:768px){

    .formula-card{

        padding:8px 5px;

        margin:10px 0;
    }

}
/* =====================================
   RECOGNITION CHAINS
===================================== */

.chain-card{

    background:#ffffff;

    border:1px solid #e2e8f0;

    border-left:5px solid #2563eb;

    border-radius:14px;

    padding:14px;

    margin:14px 0;
}

.chain-title{

    font-size:1rem;

    font-weight:700;

    color:#0f172a;

    margin-bottom:12px;
}

.chain-label{

    font-size:0.78rem;

    font-weight:700;

    letter-spacing:0.5px;

    color:#2563eb;

    text-transform:uppercase;

    margin-top:10px;

    margin-bottom:6px;
}

.chain-content{

    color:#334155;

    line-height:1.6;
}

@media(max-width:768px){

    .chain-card{

        padding:10px;

        margin:10px 0;
    }
}
/* Formula Highlight */

.formula-highlight{

    background:#f8fafc;

    border-left:4px solid #2563eb;

    border-radius:12px;

    padding:20px;

    margin:20px 0;

    text-align:center;

    overflow-x:auto;
}

/* Recall Box */

.recall-box{

    background:#eff6ff;

    border-left:4px solid #2563eb;

    border-radius:12px;

    padding:18px;

    margin:20px 0;

    color:#1e293b;
}

/* Warning Box */

.warning-box{

    background:#fff7ed;

    border-left:4px solid #f97316;

    border-radius:12px;

    padding:18px;

    margin:20px 0;

    color:#7c2d12;
}

/* MathJax Support */

.MathJax,
.MathJax_Display{

    overflow-x:auto;

    overflow-y:hidden;
}

/* Formula Spacing */

.formula-card .MathJax_Display,
.formula-highlight .MathJax_Display{

    margin:0.8em 0 !important;
}
/* =====================================
   CONTINUE LEARNING
===================================== */

.continue-learning{

    padding:20px 20px 50px;
}

/* =====================================
   STORE
===================================== */

.store-section{

    background:#ffffff;

    text-align:center;

    padding:70px 20px;

    border-top:1px solid #e5e7eb;
}

.store-section h2{

    color:#0f172a;

    margin-bottom:12px;
}

.store-section p{

    color:#64748b;

    max-width:650px;

    margin:auto;
}

.store-btn{

    display:inline-block;

    margin-top:25px;

    background:#0f172a;

    color:#ffffff;

    padding:14px 24px;

    border-radius:12px;

    font-weight:600;

    transition:0.3s ease;
}

.store-btn:hover{

    background:#1e293b;
}

/* =====================================
   FOOTER
===================================== */

.site-footer{

    background:#ffffff;

    border-top:1px solid #e5e7eb;

    text-align:center;

    padding:35px 20px;
}

.footer-links{

    margin-bottom:12px;
}

.footer-links a{

    margin:0 10px;

    color:#64748b;
}

.footer-links a:hover{

    color:#0f172a;
}

.site-footer p{

    color:#94a3b8;

    font-size:0.9rem;
}

/* =====================================
   TABLET
===================================== */

@media(min-width:768px){

    .lesson-hero h1{

        font-size:2.6rem;
    }

    .hub-grid{

        grid-template-columns:
        repeat(2,1fr);
    }
}

/* =====================================
   DESKTOP
===================================== */

@media(min-width:1000px){

    .lesson-hero,
    .chapter-dna,
    .learning-hub,
    .download-section,
    .lesson-content,
    .continue-learning{

        max-width:1000px;

        margin:auto;
    }

    .hub-grid{

        grid-template-columns:
        repeat(4,1fr);
    }

    .lesson-hero h1{

        font-size:3rem;
    }

    .content-card{

        padding:30px;
    }
}