/* ========================================
   ekian.dev — Lesson Page Styles
   ======================================== */

/* --- Lesson Layout --- */
.lesson-page {
    padding-top: 64px;
}

.lesson-hero-bar {
    background: var(--off-white);
    border-bottom: 1px solid var(--gray-100);
    padding: 14px 0;
}

.lesson-breadcrumb {
    font-size: 13px;
    color: var(--gray-500);
    display: flex;
    align-items: center;
    gap: 8px;
}

.lesson-breadcrumb a {
    color: var(--gray-500);
    transition: color var(--transition);
}

.lesson-breadcrumb a:hover {
    color: var(--black);
}

.breadcrumb-sep {
    color: var(--gray-300);
}

.lesson-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 48px 24px 80px;
    display: grid;
    grid-template-columns: 1fr 280px;
    gap: 64px;
    align-items: start;
}

/* --- Lesson Body --- */
.lesson-body {
    max-width: 720px;
}

.lesson-header-info {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.lesson-est {
    font-size: 13px;
    color: var(--gray-500);
}

.lesson-page h1 {
    font-size: clamp(28px, 4vw, 38px);
    font-weight: 800;
    letter-spacing: -0.035em;
    color: var(--black);
    line-height: 1.15;
    margin-bottom: 16px;
}

.lesson-lead {
    font-size: 17px;
    color: var(--gray-600);
    line-height: 1.65;
    margin-bottom: 12px;
}

.lesson-divider {
    border: none;
    border-top: 1px solid var(--gray-200);
    margin: 36px 0;
}

.lesson-body h2 {
    font-size: 22px;
    font-weight: 700;
    color: var(--black);
    letter-spacing: -0.02em;
    margin-top: 40px;
    margin-bottom: 16px;
    scroll-margin-top: 90px;
}

.lesson-body p {
    font-size: 15px;
    color: var(--gray-700);
    line-height: 1.7;
    margin-bottom: 16px;
}

.lesson-body strong {
    color: var(--black);
    font-weight: 600;
}

/* --- Ordered Steps --- */
.lesson-steps {
    margin: 20px 0 24px;
    padding-left: 0;
    list-style: none;
    counter-reset: step;
}

.lesson-steps li {
    counter-increment: step;
    position: relative;
    padding: 10px 0 10px 44px;
    font-size: 15px;
    color: var(--gray-700);
    line-height: 1.6;
    border-bottom: 1px solid var(--gray-100);
}

.lesson-steps li:last-child {
    border-bottom: none;
}

.lesson-steps li::before {
    content: counter(step);
    position: absolute;
    left: 0;
    top: 10px;
    width: 28px;
    height: 28px;
    background: var(--gray-100);
    color: var(--gray-700);
    font-size: 12px;
    font-weight: 700;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* --- Callout --- */
.lesson-callout {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    padding: 16px 20px;
    font-size: 14px;
    color: var(--gray-700);
    line-height: 1.6;
    margin: 20px 0;
}

.lesson-callout strong {
    color: var(--gray-800);
}

/* --- Concept Grid --- */
.concept-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin: 20px 0 28px;
}

.concept-item {
    padding: 20px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    background: var(--white);
}

.concept-item h4 {
    font-size: 14px;
    font-weight: 700;
    color: var(--black);
    margin-bottom: 6px;
}

.concept-item p {
    font-size: 13px;
    color: var(--gray-600);
    line-height: 1.55;
    margin-bottom: 0;
}

/* --- Shortcut Table --- */
.shortcut-table {
    margin: 20px 0;
}

.shortcut-row {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 10px 0;
    border-bottom: 1px solid var(--gray-100);
    font-size: 14px;
    color: var(--gray-700);
}

.shortcut-row:last-child {
    border-bottom: none;
}

.shortcut-key {
    font-family: var(--font-mono);
    font-size: 12px;
    font-weight: 600;
    background: var(--gray-100);
    border: 1px solid var(--gray-200);
    padding: 3px 10px;
    border-radius: 4px;
    color: var(--gray-800);
    min-width: 100px;
    text-align: center;
    flex-shrink: 0;
}

/* --- Challenge Block --- */
.lesson-challenge {
    background: var(--gray-50);
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 28px;
    margin: 32px 0;
}

.lesson-challenge h3 {
    font-size: 16px;
    font-weight: 700;
    color: var(--black);
    margin-bottom: 12px;
}

.lesson-challenge p {
    font-size: 14px;
    margin-bottom: 10px;
}

.lesson-challenge p:last-child {
    margin-bottom: 0;
}

.challenge-hint {
    color: var(--gray-500) !important;
    font-style: italic;
}

/* --- Lesson Nav Footer --- */
.lesson-nav-footer {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    margin-top: 48px;
    padding-top: 32px;
    border-top: 1px solid var(--gray-200);
}

.lesson-nav-prev,
.lesson-nav-next {
    display: flex;
    flex-direction: column;
    gap: 4px;
    padding: 16px 20px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    transition: all var(--transition);
    min-width: 180px;
}

.lesson-nav-next {
    text-align: right;
    margin-left: auto;
}

.lesson-nav-prev:not(.disabled):hover,
.lesson-nav-next:hover {
    border-color: var(--gray-400);
    box-shadow: var(--shadow-sm);
}

.lesson-nav-prev.disabled {
    opacity: 0.4;
    cursor: default;
}

.nav-dir {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--gray-500);
}

.nav-lesson-name {
    font-size: 14px;
    font-weight: 600;
    color: var(--black);
}

/* --- Sidebar --- */
.lesson-sidebar {
    position: sticky;
    top: 88px;
}

.sidebar-toc {
    margin-bottom: 32px;
}

.sidebar-heading {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--gray-500);
    margin-bottom: 14px;
}

.toc-link {
    display: block;
    font-size: 13px;
    color: var(--gray-500);
    padding: 6px 0;
    padding-left: 14px;
    border-left: 2px solid var(--gray-200);
    transition: all var(--transition);
}

.toc-link:hover,
.toc-link.active {
    color: var(--black);
    border-left-color: var(--black);
}

.sidebar-cta {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    padding: 20px;
}

.sidebar-cta p {
    font-size: 13px;
    color: var(--gray-600);
    line-height: 1.55;
    margin-bottom: 14px;
}

/* --- Responsive --- */
@media (max-width: 1024px) {
    .lesson-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .lesson-sidebar {
        position: static;
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 20px;
    }
}

@media (max-width: 768px) {
    .lesson-container {
        padding: 32px 20px 60px;
    }

    .concept-grid {
        grid-template-columns: 1fr;
    }

    .lesson-sidebar {
        grid-template-columns: 1fr;
    }

    .lesson-nav-footer {
        flex-direction: column;
    }

    .lesson-nav-next {
        text-align: left;
    }
}