/* ========================================================================
   Reset & base
   ======================================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ---------- Theme variables ---------- */
:root {
    /* Default = dark */
    --bg-primary: #0a0e1a;
    --bg-secondary: #11162a;
    --bg-card: #161b30;
    --bg-elevated: #1c2240;
    --bg-code: #0d1126;
    --border: #252b4a;
    --border-strong: #2f3661;
    --text-primary: #e8ebf5;
    --text-secondary: #a0a8c4;
    --text-muted: #6b7299;
    --accent-blue: #818cf8;
    --accent-purple: #c084fc;
    --accent-cyan: #22d3ee;
    --gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --gradient-soft: linear-gradient(135deg, rgba(99, 102, 241, 0.18) 0%, rgba(168, 85, 247, 0.18) 100%);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.18);
    --shadow-card: 0 12px 40px rgba(0, 0, 0, 0.35);
    --bg-glow-1: rgba(99, 102, 241, 0.08);
    --bg-glow-2: rgba(168, 85, 247, 0.08);
    --code-comment: #6b7299;
    --code-string: #a5d6a7;
    --code-keyword: #c084fc;
    --code-fn: #60a5fa;
    --code-num: #f59e0b;
    --code-cmd: #22d3ee;
    --code-text: #e8ebf5;
    --navbar-bg: rgba(10, 14, 26, 0.85);
}

[data-theme="light"] {
    --bg-primary: #f6f7fb;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-elevated: #eef0f7;
    --bg-code: #f3f4fb;
    --border: #e3e6ef;
    --border-strong: #c8cce0;
    --text-primary: #131628;
    --text-secondary: #4a5172;
    --text-muted: #7a82a0;
    --accent-blue: #4f46e5;
    --accent-purple: #8b5cf6;
    --accent-cyan: #0891b2;
    --gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --gradient-soft: linear-gradient(135deg, rgba(99, 102, 241, 0.10) 0%, rgba(168, 85, 247, 0.10) 100%);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);
    --shadow-card: 0 8px 30px rgba(20, 25, 60, 0.08);
    --bg-glow-1: rgba(99, 102, 241, 0.06);
    --bg-glow-2: rgba(168, 85, 247, 0.06);
    --code-comment: #8088a8;
    --code-string: #2e7d32;
    --code-keyword: #7c3aed;
    --code-fn: #2563eb;
    --code-num: #d97706;
    --code-cmd: #0891b2;
    --code-text: #1a1d2e;
    --navbar-bg: rgba(255, 255, 255, 0.85);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    transition: background-color 0.25s ease, color 0.25s ease;
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    background-image:
        radial-gradient(circle at 20% 10%, var(--bg-glow-1), transparent 50%),
        radial-gradient(circle at 80% 80%, var(--bg-glow-2), transparent 50%);
    pointer-events: none;
    z-index: -1;
}

/* ========================================================================
   Navbar
   ======================================================================== */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--navbar-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    transition: background-color 0.25s ease, border-color 0.25s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.9rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    text-decoration: none;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
    flex-shrink: 0;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
    list-style: none;
    align-items: center;
}

.nav-links > li > a,
.nav-dropdown-trigger {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.5rem 0.9rem;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 500;
    transition: color 0.15s, background-color 0.15s;
    background: transparent;
    border: none;
    font-family: inherit;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    line-height: 1.4;
}

.nav-links > li > a:hover,
.nav-dropdown-trigger:hover,
.has-dropdown.open .nav-dropdown-trigger {
    color: var(--text-primary);
    background: var(--bg-card);
}

.nav-links > li > a.active {
    color: var(--text-primary);
    background: var(--gradient-soft);
    border: 1px solid var(--border);
    padding: calc(0.5rem - 1px) calc(0.9rem - 1px);
}

.nav-dropdown-trigger svg {
    transition: transform 0.2s;
}

.has-dropdown.open .nav-dropdown-trigger svg {
    transform: rotate(180deg);
}

.has-dropdown {
    position: relative;
}

.nav-dropdown {
    position: absolute;
    top: calc(100% + 0.5rem);
    left: 50%;
    transform: translate(-50%, -8px);
    min-width: 760px;
    max-width: calc(100vw - 2rem);
    max-height: calc(100vh - 100px);
    overflow-y: auto;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.25rem;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.25rem 1.5rem;
    box-shadow: var(--shadow-card);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s;
    z-index: 110;
}

.has-dropdown.open .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translate(-50%, 0);
}

.nav-dropdown:has(> .dropdown-section:only-child) {
    grid-template-columns: 1fr;
    min-width: 240px;
}

.dropdown-section {
    display: flex;
    flex-direction: column;
    gap: 0.15rem;
}

.dropdown-title {
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 0.4rem;
    font-weight: 800;
    padding: 0 0.6rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    width: fit-content;
}

.dropdown-section a {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.45rem 0.6rem;
    border-radius: 6px;
    font-size: 0.92rem;
    transition: color 0.15s, background-color 0.15s;
}

.dropdown-section a:hover,
.dropdown-section a.active {
    background: var(--gradient-soft);
    color: var(--text-primary);
}

/* ---------- Theme toggle ---------- */
.theme-toggle {
    width: 38px;
    height: 38px;
    border-radius: 8px;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: color 0.15s, background-color 0.15s, border-color 0.15s;
    flex-shrink: 0;
}

.theme-toggle:hover {
    color: var(--text-primary);
    background: var(--bg-card);
    border-color: var(--border-strong);
}

.theme-toggle .icon-sun { display: block; }
.theme-toggle .icon-moon { display: none; }
[data-theme="light"] .theme-toggle .icon-sun { display: none; }
[data-theme="light"] .theme-toggle .icon-moon { display: block; }

/* ---------- Burger toggle ---------- */
.nav-toggle {
    display: none;
    width: 38px;
    height: 38px;
    border-radius: 8px;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    cursor: pointer;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.nav-toggle:hover {
    color: var(--text-primary);
    background: var(--bg-card);
}

/* ========================================================================
   Layout
   ======================================================================== */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

/* ========================================================================
   Hero
   ======================================================================== */
.hero {
    text-align: center;
    padding: 5rem 2rem 4rem;
    max-width: 900px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-block;
    padding: 0.4rem 1rem;
    background: var(--gradient-soft);
    border: 1px solid var(--border);
    border-radius: 999px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.hero h1 {
    font-size: clamp(2rem, 5vw, 3.8rem);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: 1.5rem;
}

.hero h1 .gradient-text {
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto 2.5rem;
}

.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.9rem 1.8rem;
    background: var(--gradient);
    color: white;
    text-decoration: none;
    border-radius: 10px;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: var(--shadow-glow);
}

.hero-cta:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 40px rgba(99, 102, 241, 0.35);
}

/* ========================================================================
   Page header
   ======================================================================== */
.page-header {
    padding: 4rem 0 2rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 3rem;
}

.page-header .breadcrumb {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.page-header .breadcrumb a {
    color: var(--text-secondary);
    text-decoration: none;
}

.page-header .breadcrumb a:hover {
    color: var(--accent-blue);
}

.page-header h1 {
    font-size: clamp(1.8rem, 4vw, 3rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    margin-bottom: 1rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-header .subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 700px;
}

.page-header .badge-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1.2rem;
}

.tag {
    display: inline-block;
    padding: 0.25rem 0.7rem;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: 999px;
    font-size: 0.78rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.tag.cloud {
    border-color: var(--accent-cyan);
    color: var(--accent-cyan);
}

/* ========================================================================
   Cards grid
   ======================================================================== */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(300px, 100%), 300px));
    grid-auto-rows: 1fr;
    gap: 1.25rem;
    margin-top: 3rem;
    max-width: 940px;
}

.topic-category {
    margin-top: 2.75rem;
}

.topic-category:first-of-type {
    margin-top: 2rem;
}

.category-title {
    font-size: 1.6rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 0;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
}

.topic-category .cards-grid,
.cards-grid--trailing {
    margin-top: 1.25rem;
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.25rem;
    text-decoration: none;
    color: var(--text-primary);
    transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--gradient);
    opacity: 0;
    transition: opacity 0.25s;
}

.card:hover {
    transform: translateY(-4px);
    border-color: var(--accent-blue);
    box-shadow: var(--shadow-card);
}

.card:hover::before {
    opacity: 1;
}

.card.is-disabled {
    opacity: 0.55;
    cursor: default;
}

.card.is-disabled:hover {
    transform: none;
    border-color: var(--border);
    box-shadow: none;
}

.card.is-disabled:hover::before {
    opacity: 0;
}

.card-icon {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: var(--gradient-soft);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.95rem;
    margin-bottom: 0.85rem;
    font-weight: 700;
    color: var(--accent-blue);
    flex-shrink: 0;
}

.card h3 {
    font-size: 1.05rem;
    margin-bottom: 0.4rem;
    letter-spacing: -0.01em;
    line-height: 1.3;
}

.card p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.45;
    flex-grow: 1;
}

.card .card-arrow {
    margin-top: 0.85rem;
    color: var(--accent-blue);
    font-size: 0.82rem;
    font-weight: 500;
}

/* ========================================================================
   Sections
   ======================================================================== */
.section {
    margin-bottom: 3rem;
}

.section-title {
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 0.6rem;
    letter-spacing: -0.02em;
    display: flex;
    align-items: center;
    gap: 0.6rem;
}

.section-title::before {
    content: "";
    width: 4px;
    height: 22px;
    background: var(--gradient);
    border-radius: 2px;
    flex-shrink: 0;
}

.section-intro {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.section h2 {
    font-size: 1.7rem;
    font-weight: 700;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
    display: flex;
    align-items: center;
    gap: 0.6rem;
}

.section h2::before {
    content: "";
    width: 4px;
    height: 22px;
    background: var(--gradient);
    border-radius: 2px;
    flex-shrink: 0;
}

.section h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin: 1.8rem 0 0.8rem;
    color: var(--text-primary);
}

.section p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.section ul, .section ol {
    color: var(--text-secondary);
    margin: 0 0 1rem 1.5rem;
}

.section li {
    margin-bottom: 0.5rem;
}

.section strong {
    color: var(--text-primary);
}

.section a {
    color: var(--accent-blue);
    text-decoration: none;
    word-break: break-word;
}

.section a:hover {
    text-decoration: underline;
}

/* ========================================================================
   Info boxes
   ======================================================================== */
.info-box {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-left: 3px solid var(--accent-blue);
    border-radius: 10px;
    padding: 1.1rem 1.4rem;
    margin: 1.5rem 0;
}

.info-box.tip { border-left-color: var(--accent-cyan); }
.info-box.warning { border-left-color: #f59e0b; }

.info-box .info-title {
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.4rem;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.info-box p { margin: 0; color: var(--text-secondary); }

/* ========================================================================
   Code blocks
   ======================================================================== */
.code-block {
    position: relative;
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 12px;
    margin: 1.2rem 0;
    overflow: hidden;
}

.code-block-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.55rem 1rem;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    font-size: 0.85rem;
    gap: 1rem;
}

.code-block-lang {
    color: var(--text-muted);
    font-family: "Fira Code", "Consolas", monospace;
    text-transform: lowercase;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.copy-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 0.3rem 0.8rem;
    border-radius: 6px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: color 0.15s, background-color 0.15s, border-color 0.15s;
    font-family: inherit;
    flex-shrink: 0;
}

.copy-btn:hover {
    background: var(--gradient-soft);
    color: var(--text-primary);
    border-color: var(--accent-blue);
}

.copy-btn.copied {
    background: rgba(34, 211, 238, 0.15);
    color: var(--accent-cyan);
    border-color: var(--accent-cyan);
}

.code-block pre {
    margin: 0;
    padding: 1.2rem;
    overflow-x: auto;
}

.code-block code {
    font-family: "Fira Code", "Consolas", "Monaco", monospace;
    font-size: 0.88rem;
    color: var(--code-text);
    line-height: 1.6;
    white-space: pre;
}

p code, li code {
    background: var(--bg-elevated);
    padding: 0.15rem 0.45rem;
    border-radius: 4px;
    font-family: "Fira Code", "Consolas", monospace;
    font-size: 0.88em;
    color: var(--accent-cyan);
    border: 1px solid var(--border);
}

kbd {
    background: var(--bg-elevated);
    border: 1px solid var(--border-strong);
    border-bottom-width: 2px;
    border-radius: 4px;
    padding: 0.05rem 0.4rem;
    font-family: inherit;
    font-size: 0.85em;
    color: var(--text-primary);
}

.tk-comment { color: var(--code-comment); font-style: italic; }
.tk-string  { color: var(--code-string); }
.tk-keyword { color: var(--code-keyword); }
.tk-fn      { color: var(--code-fn); }
.tk-num     { color: var(--code-num); }
.tk-cmd     { color: var(--code-cmd); }

/* ========================================================================
   Step list
   ======================================================================== */
.steps {
    counter-reset: step-counter;
    list-style: none;
    margin: 1.5rem 0 !important;
    padding: 0;
}

.steps > li {
    counter-increment: step-counter;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.4rem 1.4rem 1.4rem 3.4rem;
    margin-bottom: 1rem !important;
    position: relative;
}

.steps > li::before {
    content: counter(step-counter);
    position: absolute;
    left: 0.9rem;
    top: 1.3rem;
    width: 2rem;
    height: 2rem;
    background: var(--gradient);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.9rem;
}

.steps h4 {
    color: var(--text-primary);
    font-size: 1.05rem;
    margin-bottom: 0.5rem;
}

/* ========================================================================
   Footer
   ======================================================================== */
.footer {
    border-top: 1px solid var(--border);
    margin-top: 5rem;
    padding: 2rem;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer a {
    color: var(--accent-blue);
    text-decoration: none;
}

.footer a:hover { text-decoration: underline; }

.footer-meta {
    margin-top: 0.5rem;
    font-size: 0.85rem;
    opacity: 0.85;
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
}

.linkedin-link {
    display: inline-flex;
    align-items: center;
    color: var(--text-muted);
    transition: color 0.15s ease;
}

.linkedin-link:hover { color: #0a66c2; text-decoration: none; }

/* ========================================================================
   Responsive
   ======================================================================== */

/* Tablet & smaller desktops — switch to hamburger early enough */
@media (max-width: 1024px) {
    .nav-toggle {
        display: inline-flex;
    }

    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-secondary);
        border-bottom: 1px solid var(--border);
        flex-direction: column;
        align-items: stretch;
        padding: 0.75rem;
        gap: 0.15rem;
        max-height: calc(100vh - 70px);
        overflow-y: auto;
        box-shadow: var(--shadow-card);
        display: none;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links > li {
        width: 100%;
    }

    .nav-links > li > a,
    .nav-dropdown-trigger {
        width: 100%;
        padding: 0.7rem 0.9rem;
        justify-content: space-between;
    }

    .nav-dropdown,
    .nav-dropdown:has(> .dropdown-section:only-child) {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        display: grid;
        grid-template-columns: 1fr;
        background: transparent;
        border: none;
        box-shadow: none;
        padding: 0.25rem 0 0.5rem 0.5rem;
        min-width: 0;
        max-width: none;
        max-height: none;
        overflow: visible;
        gap: 0.75rem;
    }

    .dropdown-title {
        margin-top: 0.4rem;
    }

    .has-dropdown .nav-dropdown-trigger svg {
        display: none; /* the dropdown is always shown on mobile */
    }
}

@media (max-width: 640px) {
    .nav-container {
        padding: 0.75rem 1.2rem;
    }

    .container {
        padding: 2rem 1.2rem;
    }

    .hero {
        padding: 3rem 1.2rem 2rem;
    }

    .page-header {
        padding: 2rem 0 1.5rem;
    }

    .steps > li {
        padding: 1.2rem 1rem 1.2rem 3rem;
    }

    .code-block pre {
        padding: 1rem;
    }

    .code-block code {
        font-size: 0.82rem;
    }
}

@media (max-width: 380px) {
    .nav-logo {
        font-size: 1.1rem;
    }
}

/* Reduce motion preference */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Focus visible for accessibility */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--accent-blue);
    outline-offset: 2px;
    border-radius: 6px;
}