/* ========================================
   CSS Variables for Theme Support
   ======================================== */
:root {
    --bg-gradient-start: #eff6ff;
    --bg-gradient-mid: #f8fafc;
    --bg-gradient-end: #eef2ff;

    --card-bg: rgba(255, 255, 255, 0.92);
    --card-border: rgba(99, 102, 241, 0.2);
    --card-shadow: rgba(30, 64, 175, 0.08);
    --card-shadow-hover: rgba(30, 64, 175, 0.15);

    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --text-accent: #4f46e5;
    --text-link: #2563eb;

    --tag-bg: rgba(99, 102, 241, 0.1);
    --tag-text: #4f46e5;

    --module-hover: rgba(99, 102, 241, 0.05);
    --module-border: rgba(99, 102, 241, 0.15);

    --content-code-bg: #f1f5f9;
    --content-blockquote-border: #6366f1;
    --content-blockquote-bg: rgba(99, 102, 241, 0.05);
    --content-table-header: #f1f5f9;
    --content-table-border: #e2e8f0;

    color-scheme: light;
}

[data-theme="dark"] {
    --bg-gradient-start: #0f172a;
    --bg-gradient-mid: #1e293b;
    --bg-gradient-end: #0f172a;

    --card-bg: rgba(30, 41, 59, 0.85);
    --card-border: rgba(71, 85, 105, 0.5);
    --card-shadow: rgba(0, 0, 0, 0.3);
    --card-shadow-hover: rgba(0, 0, 0, 0.4);

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-accent: #818cf8;
    --text-link: #60a5fa;

    --tag-bg: rgba(129, 140, 248, 0.15);
    --tag-text: #a5b4fc;

    --module-hover: rgba(129, 140, 248, 0.08);
    --module-border: rgba(71, 85, 105, 0.5);

    --content-code-bg: #1e293b;
    --content-blockquote-border: #818cf8;
    --content-blockquote-bg: rgba(129, 140, 248, 0.08);
    --content-table-header: #1e293b;
    --content-table-border: #334155;

    color-scheme: dark;
}

/* ========================================
   Base Styles
   ======================================== */
* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
    min-height: 100vh;
    background: linear-gradient(160deg, var(--bg-gradient-start) 0%, var(--bg-gradient-mid) 45%, var(--bg-gradient-end) 100%);
    padding: clamp(1rem, 4vw, 2.5rem) clamp(0.75rem, 5vw, 2rem);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    overflow-x: hidden;
    transition: background 0.3s ease;
    color: var(--text-primary);
}

.container {
    width: min(100%, 52rem);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: clamp(0.85rem, 2.5vw, 1.5rem);
}

/* ========================================
   Theme Toggle
   ======================================== */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 1000;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 2rem;
    padding: 0.25rem;
    display: flex;
    gap: 0.15rem;
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 8px var(--card-shadow);
}

.theme-btn {
    border: none;
    background: transparent;
    border-radius: 50%;
    width: 2rem;
    height: 2rem;
    cursor: pointer;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.theme-btn.active {
    background: var(--tag-bg);
    box-shadow: 0 1px 3px var(--card-shadow);
}

/* ========================================
   Cards
   ======================================== */
.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    padding: clamp(1.25rem, 3vw, 2rem);
    box-shadow: 0 4px 16px var(--card-shadow);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}

/* ========================================
   Header
   ======================================== */
.header {
    text-align: center;
    padding: clamp(1.5rem, 4vw, 2.5rem);
}

.site-title {
    font-size: clamp(1.5rem, 4vw, 2.2rem);
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.site-subtitle {
    font-size: clamp(0.85rem, 2.5vw, 1.05rem);
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 0.75rem;
}

.site-author {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.site-author a {
    color: var(--text-accent);
    text-decoration: none;
    font-weight: 600;
}

.site-author a:hover { text-decoration: underline; }

/* ========================================
   Handbooks Grid
   ======================================== */
.handbooks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 22rem), 1fr));
    gap: clamp(0.85rem, 2.5vw, 1.25rem);
}

.handbook-card {
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.handbook-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px var(--card-shadow-hover);
    border-color: var(--text-accent);
}

.handbook-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
}

.handbook-title {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.35rem;
}

.handbook-audience {
    font-size: 0.8rem;
    color: var(--text-accent);
    font-weight: 600;
    margin-bottom: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.handbook-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.55;
    margin-bottom: 1rem;
}

.handbook-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-bottom: 0.75rem;
}

.tag {
    background: var(--tag-bg);
    color: var(--tag-text);
    font-size: 0.72rem;
    font-weight: 600;
    padding: 0.25rem 0.65rem;
    border-radius: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.handbook-meta {
    display: flex;
    justify-content: space-between;
    font-size: 0.78rem;
    color: var(--text-secondary);
    padding-top: 0.75rem;
    border-top: 1px solid var(--card-border);
}

/* ========================================
   Module Viewer
   ======================================== */
.module-viewer, .content-viewer {
    animation: fadeIn 0.3s ease;
}

.hidden { display: none !important; }

.viewer-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.25rem;
    flex-wrap: wrap;
}

.viewer-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
    flex: 1;
}

.btn-action {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1rem;
    border: 1px solid var(--card-border);
    border-radius: 0.5rem;
    background: var(--card-bg);
    color: var(--text-primary);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.btn-action:hover {
    background: var(--module-hover);
    border-color: var(--text-accent);
    color: var(--text-accent);
}

.module-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.module-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.85rem 1rem;
    border: 1px solid var(--module-border);
    border-radius: 0.65rem;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
    color: var(--text-primary);
}

.module-item:hover {
    background: var(--module-hover);
    border-color: var(--text-accent);
    transform: translateX(4px);
}

.module-number {
    width: 2rem;
    height: 2rem;
    border-radius: 0.5rem;
    background: var(--tag-bg);
    color: var(--tag-text);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    flex-shrink: 0;
}

.module-name {
    font-size: 0.9rem;
    font-weight: 500;
    flex: 1;
}

/* ========================================
   Content Viewer (Markdown Rendered)
   ======================================== */
.content-body {
    line-height: 1.7;
    font-size: 0.95rem;
    color: var(--text-primary);
}

.content-body h1 {
    font-size: 1.6rem;
    font-weight: 800;
    margin: 1.5rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--card-border);
}

.content-body h2 {
    font-size: 1.3rem;
    font-weight: 700;
    margin: 1.5rem 0 0.75rem;
    color: var(--text-accent);
}

.content-body h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 1.25rem 0 0.5rem;
}

.content-body h4 {
    font-size: 1rem;
    font-weight: 600;
    margin: 1rem 0 0.5rem;
}

.content-body p { margin-bottom: 0.85rem; }

.content-body a {
    color: var(--text-link);
    text-decoration: none;
}

.content-body a:hover { text-decoration: underline; }

.content-body ul, .content-body ol {
    margin: 0.5rem 0 1rem 1.5rem;
}

.content-body li { margin-bottom: 0.35rem; }

.content-body code {
    background: var(--content-code-bg);
    padding: 0.15rem 0.4rem;
    border-radius: 0.25rem;
    font-size: 0.85em;
    font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
}

.content-body pre {
    background: var(--content-code-bg);
    border: 1px solid var(--card-border);
    border-radius: 0.5rem;
    padding: 1rem;
    overflow-x: auto;
    margin: 1rem 0;
    font-size: 0.82rem;
    line-height: 1.5;
}

.content-body pre code {
    background: none;
    padding: 0;
}

.content-body blockquote {
    border-left: 4px solid var(--content-blockquote-border);
    background: var(--content-blockquote-bg);
    padding: 0.75rem 1rem;
    margin: 1rem 0;
    border-radius: 0 0.5rem 0.5rem 0;
    color: var(--text-secondary);
}

.content-body blockquote strong {
    color: var(--text-primary);
}

.content-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
    font-size: 0.85rem;
    overflow-x: auto;
    display: block;
}

.content-body thead th {
    background: var(--content-table-header);
    font-weight: 600;
    text-align: left;
    padding: 0.6rem 0.75rem;
    border: 1px solid var(--content-table-border);
}

.content-body tbody td {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--content-table-border);
}

.content-body hr {
    border: none;
    border-top: 1px solid var(--card-border);
    margin: 1.5rem 0;
}

.content-body img {
    max-width: 100%;
    border-radius: 0.5rem;
}

/* ========================================
   Footer
   ======================================== */
.footer-credits {
    text-align: center;
    padding: 1rem 0;
}

.credits-text {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.credits-text a {
    color: var(--text-accent);
    text-decoration: none;
    font-weight: 500;
}

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

/* ========================================
   Loading
   ======================================== */
.loading-indicator {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.spinner {
    width: 2rem;
    height: 2rem;
    border: 3px solid var(--card-border);
    border-top-color: var(--text-accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 1rem;
}

/* ========================================
   Animations
   ======================================== */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ========================================
   Floating Action Buttons
   ======================================== */
.floating-actions {
    position: fixed;
    left: 1.25rem;
    bottom: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    z-index: 100;
}

/* Reserve safe space at the bottom so the last line / footer
   isn't hidden behind the floating buttons. */
body:has(#floating-actions:not(.hidden)) .container {
    padding-bottom: 6rem;
}

.floating-actions.hidden { display: none !important; }

.fab {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    border: 1px solid var(--card-border);
    background: var(--card-bg);
    color: var(--text-primary);
    font-size: 1.15rem;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.15);
    transition: opacity 0.2s ease, transform 0.2s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.fab:hover {
    background: var(--module-hover);
    border-color: var(--text-accent);
    color: var(--text-accent);
    transform: translateY(-2px);
}

.fab.is-hidden {
    opacity: 0;
    pointer-events: none;
    transform: translateY(8px);
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 640px) {
    .handbooks-grid {
        grid-template-columns: 1fr;
    }

    .handbook-meta {
        flex-direction: column;
        gap: 0.25rem;
    }

    .viewer-header {
        flex-direction: column;
        align-items: flex-start;
    }
}