:root {
    --bg-dark: #f4f6f8;
    --bg-card: rgba(255, 255, 255, 0.85);
    --primary: #3498db;
    --primary-glow: rgba(52, 152, 219, 0.3);
    --accent: #e74c3c;
    --accent-glow: rgba(231, 76, 60, 0.3);
    --text-main: #333333;
    --text-muted: #777777;
    --glass-border: #d1d8de;
    --border-color: #d1d8de;
}

*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
}

h1, h2, h3, h4, .logo {
    font-family: 'Outfit', sans-serif;
}

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

.gradient-text {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.glass {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
}

/* ══════════════════════════════
   NAVBAR
══════════════════════════════ */
.navbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: 68px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 5%;
    z-index: 1000;
    border-radius: 0 0 16px 16px;
    gap: 1rem;
}

.logo {
    font-size: 1.7rem;
    font-weight: 800;
    color: var(--text-main);
    letter-spacing: -1px;
    flex-shrink: 0;
    text-decoration: none;
}
.logo span { color: var(--primary); }

.nav-links {
    display: flex;
    list-style: none;
    gap: 1.8rem;
    margin: 0 auto;
}
.nav-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: color 0.3s;
    white-space: nowrap;
}
.nav-links a:hover { color: var(--text-main); }

.auth-buttons {
    display: flex;
    gap: 0.6rem;
    flex-shrink: 0;
}

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 36px;
    height: 36px;
    cursor: pointer;
    background: none;
    border: none;
    padding: 4px;
    z-index: 1100;
}
.hamburger span {
    display: block;
    height: 2.5px;
    background: var(--text-main);
    border-radius: 4px;
    transition: all 0.35s ease;
    transform-origin: center;
}
.hamburger.open span:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.open span:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

/* Mobile drawer */
.mobile-nav {
    display: none;
    position: fixed;
    top: 68px; left: 0; right: 0;
    background: rgba(244, 246, 248, 0.98);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 999;
    padding: 1.5rem 5% 2rem;
    flex-direction: column;
    gap: 0;
    transform: translateY(-10px);
    opacity: 0;
    transition: opacity 0.3s ease, transform 0.3s ease;
    pointer-events: none;
}
.mobile-nav.open {
    display: flex;
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
}
.mobile-nav a, .mobile-nav button.nav-link-btn {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--glass-border);
    transition: color 0.2s;
    background: none;
    border-left: none;
    border-right: none;
    border-top: none;
    text-align: left;
    cursor: pointer;
    font-family: 'Inter', sans-serif;
    width: 100%;
}
.mobile-nav a:last-of-type { border-bottom: none; }
.mobile-nav .mobile-auth {
    display: flex;
    gap: 0.8rem;
    margin-top: 1.5rem;
}
.mobile-auth .btn { flex: 1; text-align: center; }

/* ══════════════════════════════
   BUTTONS
══════════════════════════════ */
.btn {
    display: inline-block;
    padding: 10px 22px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    font-family: 'Inter', sans-serif;
    white-space: nowrap;
    text-align: center;
}
.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: white;
    box-shadow: 0 4px 15px var(--primary-glow);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--accent-glow);
}
.btn-outline {
    background: transparent;
    color: var(--text-main);
    border: 1.5px solid var(--glass-border);
}
.btn-outline:hover {
    background: rgba(52,152,219,0.08);
    border-color: var(--primary);
    color: var(--primary);
}
.btn-lg {
    padding: 14px 28px;
    font-size: 1rem;
}

/* ══════════════════════════════
   HERO
══════════════════════════════ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 100px 8% 60px;
    position: relative;
    gap: 3rem;
}
.hero::before {
    content: '';
    position: absolute;
    top: -10%; left: -5%;
    width: 500px; height: 500px;
    background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
    z-index: 0;
    filter: blur(60px);
    pointer-events: none;
}
.hero-content {
    flex: 1;
    max-width: 560px;
    position: relative;
    z-index: 1;
}
.hero-content h1 {
    font-size: clamp(2.4rem, 5vw, 4.5rem);
    line-height: 1.1;
    margin-bottom: 1.2rem;
}
.hero-content p {
    font-size: clamp(1rem, 2vw, 1.2rem);
    color: var(--text-muted);
    margin-bottom: 2rem;
    line-height: 1.7;
}
.cta-group {
    display: flex;
    gap: 0.8rem;
    flex-wrap: wrap;
}
.hero-image {
    flex: 1;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    animation: float 6s ease-in-out infinite;
    z-index: 1;
}
.hero-image img {
    max-width: 80%;
    border-radius: 16px;
    position: relative;
    z-index: 2;
    box-shadow: 0 20px 60px rgba(52,152,219,0.15);
}
.glow-bg {
    position: absolute;
    width: 80%; height: 80%;
    background: radial-gradient(circle, var(--primary-glow) 0%, transparent 60%);
    filter: blur(40px);
    z-index: 1;
}
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-18px); }
}

/* ══════════════════════════════
   SECTIONS
══════════════════════════════ */
.section {
    padding: 80px 8%;
}
.section-dark {
    background: #e5e9ed;
    border-top: 1px solid var(--glass-border);
    border-bottom: 1px solid var(--glass-border);
}
.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    text-align: center;
    margin-bottom: 0.8rem;
}
.section-subtitle {
    text-align: center;
    color: var(--text-muted);
    margin-bottom: 3rem;
    font-size: 1.1rem;
}

/* ══════════════════════════════
   FEATURES (split layout)
══════════════════════════════ */
.main-features {
    margin-top: 3.5rem;
    display: flex;
    flex-direction: column;
    gap: 5rem;
}
.feature-split {
    display: flex;
    align-items: center;
    gap: 3.5rem;
    justify-content: space-between;
}
.feature-text { flex: 1; }
.feature-text h3 {
    font-size: clamp(1.7rem, 3vw, 2.5rem);
    margin-bottom: 1rem;
    color: var(--text-main);
}
.feature-text p {
    font-size: clamp(0.95rem, 1.5vw, 1.15rem);
    color: var(--text-muted);
    line-height: 1.8;
}
.feature-image {
    flex: 1.2;
}
.feature-image img {
    width: 100%;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.12);
    border: 1px solid var(--glass-border);
}

/* ══════════════════════════════
   TUTORIALS
══════════════════════════════ */
#tutorials.section {
    padding-left: 0;
    padding-right: 0;
    padding-top: 60px;
    padding-bottom: 60px;
}
#tutorials .section-title,
#tutorials .section-subtitle {
    padding-left: 8%;
    padding-right: 8%;
}
.tutorial-wrapper {
    display: flex;
    width: 100%;
    margin: 2rem 0 0 0;
    align-items: stretch;
    border: 1px solid var(--border-color);
    background: #ffffff;
}
.tutorial-sidebar {
    display: flex;
    flex-direction: column;
    width: 230px;
    flex-shrink: 0;
    background: #f1f1f1;
    border-right: 1px solid #ccc;
    padding: 1rem 0;
}
.sidebar-topic {
    font-size: 0.8rem;
    color: #555;
    margin: 1.2rem 0 0.4rem 0;
    padding: 0 14px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    cursor: default;
    user-select: none;
}
.sidebar-topic:first-child { margin-top: 0.5rem; }

/* Mobile sidebar toggle — hidden on desktop */
.sidebar-toggle { display: none; }
.sidebar-nav-items { display: contents; /* passthrough on desktop */ }

/* Sidebar drawer overlay — hidden on desktop */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.45);
    z-index: 900;
    opacity: 0;
    transition: opacity 0.3s ease;
}
.sidebar-overlay.open {
    opacity: 1;
}

.tab-btn {
    background: transparent;
    border: none;
    color: #000;
    padding: 8px 14px;
    text-align: left;
    font-size: 0.9rem;
    font-family: 'Inter', sans-serif;
    font-weight: 400;
    cursor: pointer;
    border-radius: 0;
    transition: background-color 0.2s;
    display: block;
    width: 100%;
}
.tab-btn:hover { background: #cccccc; }
.tab-btn.active {
    background: var(--primary);
    color: #ffffff;
}

.tutorial-content-area {
    flex: 1;
    padding: 1.8rem;
    min-width: 0;
}
.tab-content {
    display: none;
    animation: fadeIn 0.35s ease;
}
.tab-content.active {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* Code window */
.code-window {
    border-radius: 4px;
    overflow: hidden;
    width: 100%;
    border: 1px solid #ccc;
    background: #ffffff;
}
.window-header {
    background: #f1f1f1;
    padding: 8px 14px;
    display: flex;
    align-items: center;
    gap: 7px;
    border-bottom: 1px solid #ccc;
}
.dot { width: 12px; height: 12px; border-radius: 50%; }
.dot.red    { background: #ff5f56; }
.dot.yellow { background: #ffbd2e; }
.dot.green  { background: #27c93f; }
.window-title {
    margin-left: auto;
    font-family: 'Inter', sans-serif;
    font-size: 0.82rem;
    color: #555;
}
.window-body {
    padding: 0;
    background: #ffffff;
    overflow-x: auto;
}
.window-body pre { margin: 0; }
.window-body code {
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    color: #000000;
}
.code-table { border-collapse: collapse; width: 100%; }
.code-table td { padding: 0; vertical-align: top; }
.code-table .line-number {
    width: 40px; min-width: 40px;
    text-align: right;
    padding: 2px 10px 2px 0;
    color: #2b91af;
    background-color: #f8f8f8;
    border-right: 1px solid #e0e0e0;
    user-select: none;
}
.code-table .line-content {
    padding: 2px 0 2px 12px;
    white-space: pre;
}
.tutorial-text h3 {
    font-size: 1.4rem;
    margin-bottom: 0.8rem;
    color: var(--text-main);
}
.tutorial-text p {
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

/* ══════════════════════════════
   DONATE
══════════════════════════════ */
.donate-container {
    display: flex;
    padding: 3.5rem;
    align-items: center;
    justify-content: space-between;
    gap: 3rem;
}
.donate-content { flex: 1; }
.donate-content h2 {
    font-size: clamp(1.8rem, 3vw, 2.5rem);
    margin-bottom: 1.2rem;
}
.donate-content p {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 1.8rem;
    line-height: 1.7;
}
.donation-tiers { display: flex; gap: 1rem; flex-wrap: wrap; }
.donate-btn {
    background: rgba(255,255,255,0.05);
    border: 1px solid var(--glass-border);
    color: var(--text-main);
    padding: 14px 22px;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.4rem;
    font-weight: 800;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.donate-btn span {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 400;
    margin-top: 4px;
}
.donate-btn:hover {
    border-color: var(--primary);
    background: rgba(52,152,219,0.1);
}
.donate-btn.active {
    background: linear-gradient(135deg, rgba(52,152,219,0.2), rgba(231,76,60,0.15));
    border-color: var(--primary);
    box-shadow: inset 0 0 20px rgba(52,152,219,0.15);
}
.donate-image {
    flex: 0.4;
    display: flex;
    justify-content: center;
}

/* ══════════════════════════════
   FOOTER
══════════════════════════════ */
footer {
    background: #0f172a;
    color: #e2e8f0;
    padding: 2.5rem 8%;
}
.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.2rem;
}
.footer-logo {
    font-size: 1.5rem;
    font-weight: 800;
    font-family: 'Outfit', sans-serif;
    color: #ffffff;
}
.footer-logo span { color: var(--primary); }
.footer-content p { color: #94a3b8; font-size: 0.9rem; }
.socials { display: flex; gap: 1rem; }
.socials a {
    color: #94a3b8;
    font-size: 1.4rem;
    transition: color 0.3s, transform 0.3s;
}
.socials a:hover { color: #ffffff; transform: translateY(-3px); }

/* ══════════════════════════════
   MODAL
══════════════════════════════ */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    padding: 1rem;
}
.modal-overlay.active { opacity: 1; pointer-events: auto; }
.modal-content {
    padding: 2.5rem;
    max-width: 580px;
    width: 100%;
    position: relative;
    text-align: center;
    transform: translateY(-20px);
    transition: transform 0.3s ease;
}
.modal-overlay.active .modal-content { transform: translateY(0); }
.close-btn {
    position: absolute;
    top: 1rem; right: 1.2rem;
    font-size: 1.8rem;
    cursor: pointer;
    color: var(--text-muted);
    transition: color 0.2s;
    line-height: 1;
}
.close-btn:hover { color: var(--accent); }
.board-options {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
}
.board-card {
    flex: 1;
    min-width: 160px;
    max-width: 220px;
    padding: 2rem 1.5rem;
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text-main);
    transition: all 0.3s ease;
    background: rgba(255,255,255,0.5);
    display: flex;
    flex-direction: column;
    align-items: center;
}
.board-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    background: rgba(255,255,255,0.9);
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}
.board-card h4 { font-size: 1.4rem; margin-bottom: 0.4rem; }
.board-card p { color: var(--text-muted); font-size: 0.9rem; }

/* ══════════════════════════════
   TABLET  (≤ 900px)
══════════════════════════════ */
@media (max-width: 900px) {
    html { font-size: 15px; }

    /* Navbar */
    .nav-links { display: none; }
    .auth-buttons { display: none; }
    .hamburger { display: flex; }

    .navbar { padding: 0 4%; }

    /* Hero */
    .hero {
        flex-direction: column;
        text-align: center;
        padding: 100px 6% 60px;
        gap: 2.5rem;
        min-height: auto;
    }
    .hero-content { max-width: 100%; }
    .cta-group { justify-content: center; }
    .hero-image { width: 100%; }
    .hero-image img { max-width: 90%; margin: 0 auto; }

    /* Sections */
    .section { padding: 60px 6%; }
    #tutorials.section { padding-left: 0; padding-right: 0; }
    #tutorials .section-title,
    #tutorials .section-subtitle { padding-left: 6%; padding-right: 6%; }

    /* Features */
    .main-features { gap: 3.5rem; }
    .feature-split {
        flex-direction: column !important;
        text-align: center;
        gap: 2rem !important;
    }
    .feature-image { width: 100%; }

    /* Donate */
    .donate-container {
        flex-direction: column;
        text-align: center;
        padding: 2.5rem;
    }
    .donate-content { display: flex; flex-direction: column; align-items: center; }
    .donate-image { display: none; }

    /* Footer */
    .footer-content { flex-direction: column; text-align: center; align-items: center; }
}

/* ══════════════════════════════
   MOBILE  (≤ 600px)
══════════════════════════════ */
@media (max-width: 600px) {
    html { font-size: 14px; }

    .navbar { height: 60px; }
    .mobile-nav { top: 60px; }

    .hero {
        padding: 90px 5% 50px;
        gap: 2rem;
    }
    .hero-content h1 { font-size: 2.2rem; }
    .cta-group { flex-direction: column; width: 100%; }
    .cta-group .btn { width: 100%; text-align: center; }

    .section { padding: 50px 5%; }

    /* ── Tutorial: slide-in sidebar drawer on mobile ── */
    .tutorial-wrapper {
        flex-direction: column;
        position: relative;
    }

    /* Toggle button — always visible bar at top */
    .sidebar-toggle {
        display: flex;
        align-items: center;
        gap: 0.6rem;
        width: 100%;
        padding: 12px 16px;
        background: #f1f1f1;
        border: none;
        border-bottom: 2px solid var(--primary);
        font-family: 'Inter', sans-serif;
        font-size: 0.95rem;
        font-weight: 700;
        color: var(--text-main);
        cursor: pointer;
        text-align: left;
        letter-spacing: 0.01em;
        transition: background 0.2s;
    }
    .sidebar-toggle:hover { background: #e4e4e4; }
    .sidebar-toggle .toggle-icon {
        margin-left: auto;
        transition: transform 0.3s ease;
        font-size: 1rem;
        color: var(--primary);
    }
    .sidebar-toggle.open .toggle-icon { transform: rotate(90deg); }

    /* Sidebar becomes a fixed drawer that slides in from the left */
    .tutorial-sidebar {
        position: fixed;
        top: 0;
        left: 0;
        width: 270px;
        height: 100vh;
        background: #f1f1f1;
        border-right: 2px solid var(--primary);
        padding: 0;
        z-index: 950;
        overflow-y: auto;
        transform: translateX(-100%);
        transition: transform 0.32s cubic-bezier(0.4, 0, 0.2, 1);
        box-shadow: 4px 0 20px rgba(0,0,0,0.15);
        display: flex;
        flex-direction: column;
    }
    .tutorial-sidebar.open {
        transform: translateX(0);
    }

    /* Sidebar header row inside drawer */
    .sidebar-drawer-header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: 14px 16px;
        background: var(--primary);
        color: #fff;
        font-family: 'Outfit', sans-serif;
        font-weight: 700;
        font-size: 1rem;
        flex-shrink: 0;
    }
    .sidebar-close-btn {
        background: none;
        border: none;
        color: #fff;
        font-size: 1.3rem;
        cursor: pointer;
        line-height: 1;
        padding: 2px 4px;
        transition: opacity 0.2s;
    }
    .sidebar-close-btn:hover { opacity: 0.7; }

    /* Show the overlay */
    .sidebar-overlay { display: block; }

    /* nav items — restore normal block flow inside drawer */
    .sidebar-nav-items {
        display: block !important;
        padding: 0.5rem 0 1rem;
    }
    .sidebar-topic {
        display: block;
        font-size: 0.75rem;
        padding: 0 16px;
        margin: 1rem 0 0.3rem;
    }
    .tab-btn {
        display: block;
        width: 100%;
        text-align: left;
        padding: 10px 20px;
        font-size: 0.95rem;
        border-radius: 0;
    }

    .tutorial-content-area { padding: 1.2rem; }
    .window-body code { font-size: 0.8rem; }

    .donate-container { padding: 1.8rem; }
    .donation-tiers { gap: 0.7rem; }
    .donate-btn { padding: 12px 16px; font-size: 1.2rem; }

    .section-title { font-size: 1.8rem; }
    .board-options { flex-direction: column; align-items: center; }
    .board-card { min-width: 80%; max-width: 100%; }

    footer { padding: 2rem 5%; }
}