:root {
    --navy: #1b2a41;
    --blue: #2c5f9b;
    --accent: #e8622c;
    --bg: #f4f6f9;
    --card: #ffffff;
    --border: #dde3ea;
    --text: #22303f;
    --muted: #5c6b7a;
    --code-bg: #1e2a38;
    --code-text: #d9e6f2;
    --radius: 10px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: "Segoe UI", Arial, Helvetica, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
}

/* ---------- Header ---------- */
header.site-header {
    background: linear-gradient(135deg, var(--navy), var(--blue));
    color: #fff;
    padding: 40px 20px 30px;
    text-align: center;
}
header.site-header .eyebrow {
    text-transform: uppercase;
    letter-spacing: 2px;
    font-size: 0.8rem;
    color: #b9cbe0;
    margin-bottom: 8px;
}
header.site-header h1 {
    margin: 0 0 10px;
    font-size: 2.2rem;
}
header.site-header p {
    margin: 0;
    color: #d7e2ee;
    max-width: 600px;
    margin: 0 auto;
}

/* ---------- Nav ---------- */
nav.site-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--navy);
    padding: 10px 20px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 6px;
}
nav.site-nav a {
    color: #cfe0f2;
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 600;
    padding: 8px 12px;
    border-radius: 20px;
    transition: background 0.2s;
}
nav.site-nav a:hover,
nav.site-nav a:focus {
    background: rgba(255, 255, 255, 0.15);
    color: #fff;
}

/* ---------- Layout ---------- */
main {
    max-width: 1000px;
    margin: 0 auto;
    padding: 10px 20px 60px;
}

section.lesson {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 30px;
    margin: 40px 0;
    scroll-margin-top: 70px;
}

section.lesson .kicker {
    color: var(--accent);
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1.5px;
}

section.lesson h2 {
    margin: 4px 0 4px;
    color: var(--navy);
    font-size: 1.6rem;
}

section.lesson .subtitle {
    color: var(--muted);
    margin: 0 0 20px;
}

section.lesson h3 {
    color: var(--blue);
    margin: 28px 0 10px;
    font-size: 1.1rem;
}

/* ---------- Code blocks ---------- */
pre {
    background: var(--code-bg);
    color: var(--code-text);
    padding: 16px 18px;
    border-radius: 8px;
    overflow-x: auto;
    font-size: 0.85rem;
    line-height: 1.5;
}
code {
    font-family: "Consolas", "Courier New", monospace;
}
p code, li code, td code {
    background: #eef1f6;
    color: var(--blue);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
}

/* ---------- Reference tables ---------- */
table.ref {
    width: 100%;
    border-collapse: collapse;
    margin: 14px 0;
    font-size: 0.92rem;
}
table.ref th, table.ref td {
    border: 1px solid var(--border);
    padding: 10px 12px;
    text-align: left;
    vertical-align: top;
}
table.ref th {
    background: #eef2f7;
    color: var(--navy);
    width: 22%;
}

/* ---------- Cards / grid ---------- */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}
.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}
@media (max-width: 700px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
}

.card {
    background: #fbfcfe;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px 18px;
}

/* ---------- LO badges ---------- */
.lo-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.lo-item {
    display: flex;
    gap: 14px;
    align-items: flex-start;
    background: #fbfcfe;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 12px 16px;
}
.lo-badge {
    flex-shrink: 0;
    background: var(--blue);
    color: #fff;
    font-weight: 700;
    font-size: 0.75rem;
    padding: 4px 10px;
    border-radius: 20px;
}

/* ---------- Heading hierarchy demo ---------- */
.heading-demo div {
    border-bottom: 1px dashed var(--border);
    padding: 6px 0;
}
.heading-demo span.tag {
    color: var(--muted);
    font-size: 0.75rem;
    margin-left: 10px;
}

/* ---------- Callouts ---------- */
.callout {
    border-left: 4px solid var(--accent);
    background: #fff4ee;
    padding: 12px 16px;
    border-radius: 0 6px 6px 0;
    margin: 16px 0;
}
.callout.tip {
    border-left-color: #2f9e5c;
    background: #eefaf1;
}
.callout.key {
    border-left-color: var(--blue);
    background: #eaf1fb;
}

/* ---------- Rendered demo boxes ---------- */
.demo-box {
    border: 1px dashed var(--border);
    border-radius: 8px;
    padding: 16px;
    background: #fbfcfe;
    margin: 12px 0;
}
.demo-box .demo-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--muted);
    margin-bottom: 10px;
}

/* ---------- Lab rubric table ---------- */
table.rubric th, table.rubric td {
    padding: 10px 12px;
}
table.rubric td:nth-child(2) {
    text-align: center;
    font-weight: 700;
    color: var(--blue);
}

/* ---------- Takeaways list ---------- */
ol.takeaways {
    counter-reset: item;
    list-style: none;
    padding-left: 0;
}
ol.takeaways li {
    counter-increment: item;
    position: relative;
    padding: 10px 0 10px 42px;
    border-bottom: 1px solid var(--border);
}
ol.takeaways li::before {
    content: counter(item);
    position: absolute;
    left: 0;
    top: 8px;
    background: var(--navy);
    color: #fff;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
}

/* ---------- Next week banner ---------- */
.next-week {
    background: var(--navy);
    color: #fff;
    text-align: center;
    padding: 30px 20px;
    margin-top: 40px;
}
.next-week .eyebrow {
    color: #9fc0e0;
    text-transform: uppercase;
    letter-spacing: 2px;
    font-size: 0.8rem;
}
.next-week h3 {
    margin: 8px 0;
    color: #fff;
}
.next-week p {
    color: #cfe0f2;
    max-width: 600px;
    margin: 0 auto;
}

/* ---------- Try it Yourself editor ---------- */
.tryit {
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    margin: 16px 0;
}
.tryit-toolbar {
    background: var(--blue);
    padding: 8px 14px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.tryit-toolbar .tryit-title {
    color: #fff;
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.5px;
}
.tryit-buttons {
    display: flex;
    gap: 8px;
}
.tryit-run, .tryit-reset {
    border: none;
    border-radius: 4px;
    padding: 6px 14px;
    font-size: 0.8rem;
    font-weight: 700;
    cursor: pointer;
}
.tryit-run {
    background: var(--accent);
    color: #fff;
}
.tryit-run:hover {
    opacity: 0.9;
}
.tryit-reset {
    background: transparent;
    color: #fff;
    border: 1px solid rgba(255, 255, 255, 0.5);
}
.tryit-reset:hover {
    background: rgba(255, 255, 255, 0.15);
}
.tryit-body {
    display: flex;
    align-items: stretch;
}
.tryit-code {
    display: block;
    width: 50%;
    box-sizing: border-box;
    border: none;
    border-right: 1px solid var(--border);
    background: var(--code-bg);
    color: var(--code-text);
    font-family: "Consolas", "Courier New", monospace;
    font-size: 0.85rem;
    line-height: 1.5;
    padding: 16px 18px;
    resize: none;
    min-height: 240px;
}
.tryit-code:focus {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}
.tryit-result {
    width: 50%;
    display: flex;
    flex-direction: column;
}
.tryit-result-label {
    background: #eef2f7;
    color: var(--muted);
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    padding: 6px 14px;
    border-bottom: 1px solid var(--border);
}
.tryit-frame {
    display: block;
    width: 100%;
    flex: 1;
    min-height: 200px;
    border: none;
    background: #fff;
}
.tryit.compact .tryit-body {
    flex-direction: column;
}
.tryit.compact .tryit-code,
.tryit.compact .tryit-result {
    width: 100%;
}
.tryit.compact .tryit-code {
    border-right: none;
    border-bottom: 1px solid var(--border);
    min-height: 150px;
    font-size: 0.9rem;
}
.tryit.compact .tryit-frame {
    min-height: 140px;
}

@media (max-width: 640px) {
    .tryit-body {
        flex-direction: column;
    }
    .tryit-code, .tryit-result {
        width: 100%;
    }
    .tryit-code {
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
}

footer.site-footer {
    text-align: center;
    padding: 18px;
    color: var(--muted);
    font-size: 0.85rem;
}