/* ================================================================
   TechWithTKS - Main Stylesheet
   Design System: Light & Dark Mode | Blue Primary | Flat Borders
   ================================================================ */

/* ================================================================
   CSS DESIGN TOKENS — LIGHT MODE (default)
   ================================================================ */
:root {
    /* ---- Backgrounds ---- */
    --bg: #FFFFFF;
    --bg-surface: #F9FAFB;
    --bg-card: #FFFFFF;
    --bg-elevated: #FFFFFF;

    /* ---- Text ---- */
    --text-primary: #111827;
    --text-secondary: #4B5563;
    --text-muted: #6B7280;
    --text-disabled: #9CA3AF;

    /* ---- Borders ---- */
    --border: #E5E7EB;
    --border-strong: #D1D5DB;

    /* ---- Brand / Primary ---- */
    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --primary-text: #FFFFFF;

    /* ---- Buttons ---- */
    --btn-disabled-bg: #E5E7EB;
    --btn-disabled-text: #9CA3AF;

    /* ---- Status ---- */
    --success: #16A34A;
    --warning: #F59E0B;
    --error: #DC2626;
    --info: #0284C7;

    /* ---- Focus ---- */
    --focus-ring: rgba(37, 99, 235, 0.35);

    /* ---- Shadows ---- */
    --shadow-soft: 0 4px 12px rgba(0, 0, 0, 0.08);

    /* ---- Header ---- */
    --header-bg: #FFFFFF;
    --header-border: #E5E7EB;

    /* ---- Typography ---- */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    /* ---- Spacing ---- */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;

    /* ---- Radius ---- */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-pill: 999px;

    /* ---- Transitions ---- */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;

    /* ---- Container ---- */
    --container-max: 1200px;

    /* ---- Hover Lift ---- */
    --hover-lift: translateY(-3px);

    /* ---- Redesign Tokens (Phase A) ---- */
    --background-dark: #0F172A;
    --background-light: #F8FAFC;
    --card-bg-dark: #111827;
    --border-subtle: rgba(255, 255, 255, 0.08);
    --radius-main: 16px;
    --primary-color: #2563EB;

    /* Legacy compat aliases */
    --primary-dark: #1D4ED8;
    --bg-light: #F9FAFB;
    --bg-white: #FFFFFF;
    --border-light: #E5E7EB;
    --border-hover: #2563EB;
    --text-light: #6B7280;
    --gray-50: #F9FAFB;
    --gray-100: #F3F4F6;
    --gray-200: #E5E7EB;
    --gray-300: #D1D5DB;
    --gray-800: #1F2937;
    --gray-900: #111827;
}

/* ================================================================
   DARK MODE TOKENS
   ================================================================ */
[data-theme="dark"] {
    --bg: #0B1220;
    --bg-surface: #111827;
    --bg-card: #1F2937;
    --bg-elevated: #111827;

    --text-primary: #FFFFFF;
    --text-secondary: #D1D5DB;
    --text-muted: #9CA3AF;
    --text-disabled: #6B7280;

    --border: #374151;
    --border-strong: #4B5563;

    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --primary-text: #FFFFFF;

    --btn-disabled-bg: #374151;
    --btn-disabled-text: #6B7280;

    --success: #22C55E;
    --warning: #FBBF24;
    --error: #F87171;
    --info: #38BDF8;

    --focus-ring: rgba(37, 99, 235, 0.5);
    --shadow-soft: 0 4px 14px rgba(0, 0, 0, 0.5);

    --header-bg: #111827;
    --header-border: #374151;

    /* Redesign Tokens — dark mode overrides */
    --background-dark: #0F172A;
    --background-light: #1E293B;
    --card-bg-dark: #111827;
    --border-subtle: rgba(255, 255, 255, 0.08);
    --primary-color: #3B82F6;

    /* Legacy compat */
    --primary-dark: #1D4ED8;
    --bg-light: #111827;
    --bg-white: #1F2937;
    --border-light: #374151;
    --border-hover: #2563EB;
    --text-light: #9CA3AF;
    --gray-50: #1F2937;
    --gray-100: #374151;
    --gray-200: #4B5563;
    --gray-300: #6B7280;
    --gray-800: #D1D5DB;
    --gray-900: #0B1220;
}

/* ================================================================
   BASE RESET
   ================================================================ */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color 0.3s ease, color 0.3s ease;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-fast);
}

ul {
    list-style: none;
}

button {
    font-family: var(--font-primary);
}

/* ================================================================
   SCROLL REVEAL ANIMATION — Phase 5
   ================================================================ */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

/* Respect user motion preferences */
@media (prefers-reduced-motion: reduce) {
    .reveal {
        opacity: 1;
        transform: none;
        transition: none;
    }
}

/* ================================================================
   CONTAINER
   ================================================================ */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ================================================================
   TYPOGRAPHY
   ================================================================ */
.section-title {
    font-size: clamp(1.6rem, 3.5vw, 2.25rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.section-subtitle,
.section-description {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 560px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ================================================================
   BUTTONS — Flat, pill-style. NO parallelogram / NO 3D
   ================================================================ */

/* Primary */
.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 40px;
    padding: 0 20px;
    background: var(--primary);
    color: var(--primary-text);
    font-size: 14px;
    font-weight: 600;
    font-family: var(--font-primary);
    border: none;
    border-radius: var(--radius-pill);
    cursor: pointer;
    text-decoration: none;
    transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
    white-space: nowrap;
}

.btn-primary:hover {
    background: var(--primary-hover);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.btn-primary:focus-visible {
    outline: 3px solid var(--focus-ring);
    outline-offset: 2px;
}

/* Secondary / Outline */
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 40px;
    padding: 0 20px;
    background: transparent;
    color: var(--primary);
    font-size: 14px;
    font-weight: 600;
    font-family: var(--font-primary);
    border: 1.5px solid var(--primary);
    border-radius: var(--radius-pill);
    cursor: pointer;
    text-decoration: none;
    transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
    white-space: nowrap;
}

.btn-secondary:hover {
    background: var(--primary);
    color: #ffffff;
}

/* Disabled state */
.btn-disabled,
.btn-primary:disabled,
.btn-secondary:disabled {
    background: var(--btn-disabled-bg) !important;
    color: var(--btn-disabled-text) !important;
    border-color: var(--btn-disabled-bg) !important;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

/* Legacy: keep .btn-parallelogram working but strip the skew */
.btn-parallelogram {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 40px;
    padding: 0 20px;
    background: var(--primary);
    color: #ffffff;
    font-size: 14px;
    font-weight: 600;
    font-family: var(--font-primary);
    border: none;
    border-radius: var(--radius-pill);
    cursor: pointer;
    text-decoration: none;
    transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
    white-space: nowrap;
}

.btn-parallelogram span {
    display: inline-block;
    transform: none;
}

.btn-parallelogram:hover {
    background: var(--primary-hover);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.btn-parallelogram-outline {
    background: transparent;
    border: 1.5px solid var(--primary);
    color: var(--primary);
    border-radius: var(--radius-pill);
}

.btn-parallelogram-outline:hover {
    background: var(--primary);
    color: #ffffff;
}

/* ================================================================
   CARDS — Light border, no 3D, no box-shadow depth
   ================================================================ */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    transition: border-color var(--transition-base), transform var(--transition-base);
}

.card:hover {
    border-color: var(--border-strong);
}

/* ================================================================
   TUTORIAL CARDS
   ================================================================ */
.tutorials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.tutorial-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 100%;
    transition: border-color var(--transition-base), transform var(--transition-base);
}

.tutorial-card:hover {
    border-color: var(--border-strong);
}

.card-image {
    position: relative;
    height: 200px;
    background: var(--bg-surface);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border-bottom: 1px solid var(--border);
}

.tutorial-thumbnail {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.card-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    width: 100%;
    height: 100%;
    background: var(--bg-surface);
}

.card-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    padding: 4px 10px;
    background: var(--primary);
    color: white;
    border-radius: var(--radius-pill);
    font-size: 11px;
    font-weight: 600;
}

.badge-popular {
    background: var(--success);
}

.card-content {
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    flex: 1;
}

.card-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    line-height: 1.4;
}

.card-title a {
    color: inherit;
    text-decoration: none;
}

.card-title a:hover {
    color: var(--primary);
}

.card-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
    flex: 1;
}

.card-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: center;
    padding-top: var(--spacing-xs);
    border-top: 1px solid var(--border);
    margin-bottom: var(--spacing-xs);
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.card-link {
    display: inline-block;
    color: var(--primary);
    font-weight: 600;
    font-size: 0.875rem;
    transition: color var(--transition-fast);
}

.card-link:hover {
    color: var(--primary-hover);
}

/* ================================================================
   PROJECT CARDS
   ================================================================ */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: border-color var(--transition-base), transform var(--transition-base);
}

.project-card:hover {
    border-color: var(--primary);
    transform: var(--hover-lift);
    box-shadow: var(--shadow-soft);
}

.project-image {
    position: relative;
    height: 200px;
    background: var(--bg-surface);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border-bottom: 1px solid var(--border);
}

.project-thumbnail {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.project-icon-fallback {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-surface);
}

.project-overlay {
    position: absolute;
    inset: 0;
    background: rgba(37, 99, 235, 0.85);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.project-card:hover .project-overlay {
    opacity: 1;
}

.project-content {
    padding: var(--spacing-md);
}

.project-tags {
    display: flex;
    gap: 0.5rem;
    margin-bottom: var(--spacing-sm);
    flex-wrap: wrap;
}

.tag {
    padding: 3px 10px;
    background: var(--bg-surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    font-size: 11px;
    font-weight: 600;
    transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}

.tag:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.project-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.project-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
}

.project-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    padding-top: var(--spacing-xs);
    border-top: 1px solid var(--border);
}

.project-stats .stat {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* ================================================================
   CATEGORY CARDS
   ================================================================ */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: var(--spacing-md);
}

.category-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: border-color var(--transition-base), transform var(--transition-base);
}

.category-card:hover {
    border-color: var(--primary);
    transform: var(--hover-lift);
    box-shadow: var(--shadow-soft);
}

.category-icon {
    width: 56px;
    height: 56px;
    background: var(--bg-surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    margin-bottom: var(--spacing-md);
    transition: all var(--transition-base);
}

.category-card:hover .category-icon {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

.category-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.category-count {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* ================================================================
   SECTION WRAPPERS
   ================================================================ */
.section {
    padding: var(--spacing-3xl) 0;
}

.section-header,
.section-header-centered {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

/* ================================================================
   PAGINATION
   ================================================================ */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-2xl);
    flex-wrap: wrap;
}

.pagination-btn {
    min-width: 36px;
    height: 36px;
    padding: 0 12px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-primary);
}

.pagination-btn span {
    display: inline-block;
}

.pagination-btn:hover:not(:disabled) {
    border-color: var(--primary);
    color: var(--primary);
}

.pagination-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

.pagination-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

/* ================================================================
   FOOTER
   ================================================================ */
.footer {
    background: var(--bg-elevated);
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
    margin-top: var(--spacing-3xl);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.footer-logo {
    margin-bottom: 16px;
}

.footer-description {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-top: 0;
    margin-bottom: var(--spacing-md);
    font-size: 0.9rem;
    max-width: 280px;
}

.social-links {
    display: flex;
    gap: var(--spacing-sm);
}

.social-link {
    width: 36px;
    height: 36px;
    background: var(--bg-surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

.footer-heading {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.footer-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--primary);
}

.footer-bottom {
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}

.footer-logo-image {
    height: 40px;
    width: auto;
    object-fit: contain;
}

/* ================================================================
   PAGE HEADER
   ================================================================ */
.page-header {
    padding: var(--spacing-3xl) 0 var(--spacing-2xl);
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    text-align: center;
}

.page-header-content {
    max-width: 800px;
    margin: 0 auto;
}

.page-title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.page-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ================================================================
   SEARCH & FILTER
   ================================================================ */
.search-filter {
    padding: var(--spacing-xl) 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
}

.search-box {
    position: relative;
    max-width: 480px;
    width: 100%;
}

.search-box svg {
    position: absolute;
    left: 14px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    pointer-events: none;
}

.search-input {
    width: 100%;
    padding: 0.875rem 1rem 0.875rem 3rem;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-family: var(--font-primary);
    background: var(--bg-card);
    color: var(--text-primary);
    transition: border-color var(--transition-fast);
}

.search-input::placeholder {
    color: var(--text-muted);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--focus-ring);
}

.filter-buttons {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.filter-btn {
    padding: 7px 16px;
    background: var(--bg-card);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-pill);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: var(--font-primary);
}

.filter-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.filter-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

/* ================================================================
   NO RESULTS
   ================================================================ */
.no-results-message {
    display: none;
    grid-column: 1 / -1;
    padding: var(--spacing-3xl) var(--spacing-lg);
    text-align: center;
}

.no-results-content {
    max-width: 400px;
    margin: 0 auto;
}

.no-results-content svg {
    margin: 0 auto var(--spacing-md);
    color: var(--text-muted);
}

.no-results-content h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.no-results-content p {
    color: var(--text-secondary);
}

/* ================================================================
   BOOKMARK BUTTON
   ================================================================ */
.bookmark-btn {
    transition: all var(--transition-fast);
}

.bookmark-btn.bookmarked {
    background: var(--primary) !important;
    border-color: var(--primary) !important;
    color: white !important;
}

/* ================================================================
   LOGO
   ================================================================ */
.logo-image {
    height: 38px;
    width: auto;
    object-fit: contain;
}

/* ================================================================
   GENERIC UTILITY
   ================================================================ */
.text-primary {
    color: var(--text-primary);
}

.text-secondary {
    color: var(--text-secondary);
}

.text-muted {
    color: var(--text-muted);
}

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

.bg-surface {
    background: var(--bg-surface);
}

.border-light {
    border: 1px solid var(--border);
}

/* ================================================================
   RESPONSIVE
   ================================================================ */
@media (max-width: 1024px) {
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }

    .page-title {
        font-size: 2.25rem;
    }
}

@media (max-width: 768px) {

    .tutorials-grid,
    .projects-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .page-title {
        font-size: 1.8rem;
    }

    .section-title {
        font-size: 1.6rem;
    }
}

@media (max-width: 480px) {
    .categories-grid {
        grid-template-columns: 1fr 1fr;
    }

    .filter-buttons {
        justify-content: center;
    }

    .pagination {
        gap: 0.375rem;
    }
}