/* ============================================
   PDFHub.club — Premium Design System
   iLovePDF-inspired UI
   ============================================ */

/* --- CSS Variables --- */
:root {
    --primary: #E53E3E;
    --primary-hover: #C53030;
    --accent: #6C63FF;
    --bg: #FFFFFF;
    --bg-soft: #FAFBFE;
    --card: #FFFFFF;
    --border: #E8ECF0;
    --text: #1A202C;
    --text-secondary: #5A6577;
    --text-muted: #8896A6;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.06);
    --shadow-lg: 0 12px 40px rgba(0,0,0,0.1);
    --shadow-hover: 0 8px 30px rgba(0,0,0,0.1);
    --radius: 16px;
    --radius-sm: 10px;
    --radius-xl: 24px;
    --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', Helvetica, Arial, sans-serif;
    --max-width: 1280px;
    --header-height: 68px;
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);

    /* Tool category colors */
    --color-organize: #F6A623;
    --color-optimize: #27AE60;
    --color-convert-to: #3498DB;
    --color-convert-from: #9B59B6;
    --color-edit: #E67E22;
    --color-security: #2C3E50;
    --color-ai: #6C63FF;
}

[data-theme="dark"] {
    --bg: #0F1117;
    --bg-soft: #161922;
    --card: #1C1F2E;
    --border: #2A2F40;
    --text: #F1F5F9;
    --text-secondary: #94A3B8;
    --text-muted: #64748B;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.3);
    --shadow-lg: 0 12px 40px rgba(0,0,0,0.4);
    --shadow-hover: 0 8px 30px rgba(0,0,0,0.4);
}

/* --- Reset --- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}
a { color: inherit; text-decoration: none; }
button { cursor: pointer; font-family: var(--font); border: none; outline: none; }
img { max-width: 100%; }

/* --- Sticky Header --- */
.header {
    position: sticky;
    top: 0;
    z-index: 1000;
    height: var(--header-height);
    background: rgba(255,255,255,0.92);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    transition: all var(--transition);
}
[data-theme="dark"] .header {
    background: rgba(15,17,23,0.92);
}
.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 32px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--text);
}
.logo-icon {
    width: 38px;
    height: 38px;
    background: linear-gradient(135deg, var(--primary), #FF6B6B);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1rem;
    font-weight: 700;
}

/* Header Nav */
.header-nav {
    display: flex;
    align-items: center;
    gap: 4px;
}
.header-nav > a {
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    transition: all var(--transition);
}
.header-nav > a:hover {
    color: var(--text);
    background: var(--bg-soft);
}

/* Nav Dropdown */
.nav-dropdown { position: relative; }
.nav-dropdown > .nav-trigger {
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    background: none;
    transition: all var(--transition);
}
.nav-trigger::after { content: '▾'; font-size: 0.65rem; opacity: 0.5; }
.nav-dropdown:hover > .nav-trigger { color: var(--text); background: var(--bg-soft); }

/* Mega Menu */
.mega-menu {
    position: absolute;
    top: calc(100% + 8px);
    left: 50%;
    transform: translateX(-50%);
    min-width: 680px;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    padding: 24px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.2s ease;
    z-index: 1001;
}
.nav-dropdown:hover .mega-menu {
    opacity: 1;
    visibility: visible;
}
.mega-menu-col h4 {
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    margin-bottom: 10px;
    padding-left: 10px;
}
.mega-menu-col a {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 10px;
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text);
    transition: all var(--transition);
}
.mega-menu-col a:hover {
    background: var(--bg-soft);
    color: var(--primary);
}
.mega-menu-col a .icon { font-size: 1rem; }

/* Header Right */
.header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}
.btn-login {
    padding: 8px 18px;
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    transition: all var(--transition);
}
.btn-login:hover { color: var(--text); }
.btn-signup {
    padding: 8px 20px;
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 600;
    background: var(--primary);
    color: white;
    transition: all var(--transition);
}
.btn-signup:hover { background: var(--primary-hover); transform: translateY(-1px); }
.theme-toggle {
    width: 38px; height: 38px;
    border-radius: 50%;
    background: var(--bg-soft);
    border: 1px solid var(--border);
    display: flex; align-items: center; justify-content: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    transition: all var(--transition);
}
.theme-toggle:hover { color: var(--text); box-shadow: var(--shadow-sm); }

/* --- Hero Section --- */
.hero {
    text-align: center;
    padding: 80px 32px 50px;
    position: relative;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -200px; right: -200px;
    width: 600px; height: 600px;
    background: radial-gradient(circle, rgba(229,62,62,0.04) 0%, transparent 70%);
    border-radius: 50%;
}
.hero::after {
    content: '';
    position: absolute;
    bottom: -200px; left: -200px;
    width: 500px; height: 500px;
    background: radial-gradient(circle, rgba(108,99,255,0.04) 0%, transparent 70%);
    border-radius: 50%;
}
.hero h1 {
    font-size: clamp(2.5rem, 5vw, 3.8rem);
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -0.02em;
    margin-bottom: 20px;
    position: relative;
    z-index: 1;
}
.hero p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 560px;
    margin: 0 auto;
    line-height: 1.7;
    position: relative;
    z-index: 1;
}

/* --- Category Chips --- */
.chips {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 10px;
    padding: 0 32px 40px;
    max-width: var(--max-width);
    margin: 0 auto;
}
.chip {
    padding: 9px 20px;
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1.5px solid var(--border);
    background: var(--card);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}
.chip:hover { border-color: var(--text-muted); color: var(--text); }
.chip.active {
    background: var(--text);
    color: var(--bg);
    border-color: var(--text);
}
[data-theme="dark"] .chip.active {
    background: white;
    color: #0F1117;
}

/* --- Tool Grid --- */
.tool-section {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 32px 80px;
}
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
    gap: 20px;
}
.tool-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 24px;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
}
.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
    border-color: transparent;
}
.tool-card-icon {
    width: 52px; height: 52px;
    border-radius: 14px;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.5rem;
}
.tool-card h3 {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text);
}
.tool-card p {
    font-size: 0.82rem;
    color: var(--text-muted);
    line-height: 1.5;
}
.tool-card .badge-new {
    position: absolute;
    top: 12px; right: 12px;
    padding: 3px 8px;
    border-radius: 100px;
    font-size: 0.65rem;
    font-weight: 700;
    background: var(--accent);
    color: white;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Icon Colors by Category */
.icon-organize { background: rgba(246,166,35,0.12); color: var(--color-organize); }
.icon-optimize { background: rgba(39,174,96,0.12); color: var(--color-optimize); }
.icon-convert-to { background: rgba(52,152,219,0.12); color: var(--color-convert-to); }
.icon-convert-from { background: rgba(155,89,182,0.12); color: var(--color-convert-from); }
.icon-edit { background: rgba(230,126,34,0.12); color: var(--color-edit); }
.icon-security { background: rgba(44,62,80,0.12); color: var(--color-security); }

/* --- Upload Area (tool pages) --- */
.upload-area {
    max-width: 700px;
    margin: 0 auto 40px;
    padding: 70px 40px;
    border: 2px dashed var(--border);
    border-radius: var(--radius-xl);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    background: var(--card);
}
.upload-area:hover, .upload-area.drag-over {
    border-color: var(--primary);
    background: rgba(229,62,62,0.02);
}
.upload-area .upload-icon { font-size: 3.5rem; margin-bottom: 16px; display: block; }
.upload-area h3 { font-size: 1.2rem; font-weight: 700; margin-bottom: 6px; }
.upload-area p { color: var(--text-muted); font-size: 0.9rem; }
.upload-area input[type="file"] { position: absolute; inset: 0; opacity: 0; cursor: pointer; }

/* --- Footer --- */
.footer {
    border-top: 1px solid var(--border);
    padding: 50px 32px;
    background: var(--bg-soft);
}
.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: 40px;
}
.footer-brand p { color: var(--text-muted); font-size: 0.85rem; margin-top: 12px; line-height: 1.6; }
.footer-col h4 {
    font-size: 0.75rem; font-weight: 700; text-transform: uppercase;
    letter-spacing: 0.08em; color: var(--text-muted); margin-bottom: 14px;
}
.footer-col a { display: block; color: var(--text-secondary); font-size: 0.85rem; padding: 4px 0; transition: color var(--transition); }
.footer-col a:hover { color: var(--primary); }
.footer-bottom {
    max-width: var(--max-width);
    margin: 30px auto 0;
    padding-top: 24px;
    border-top: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center;
    font-size: 0.82rem; color: var(--text-muted);
}

/* --- Buttons --- */
.btn-primary {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    padding: 14px 32px;
    background: var(--primary); color: white;
    font-size: 1rem; font-weight: 600;
    border-radius: 100px;
    transition: all var(--transition);
    box-shadow: 0 4px 15px rgba(229,62,62,0.25);
}
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-2px); box-shadow: 0 6px 25px rgba(229,62,62,0.35); }
.btn-secondary {
    padding: 12px 24px;
    background: var(--bg-soft); color: var(--text);
    font-size: 0.9rem; font-weight: 600;
    border-radius: 100px;
    border: 1px solid var(--border);
    transition: all var(--transition);
}
.btn-secondary:hover { border-color: var(--text-muted); }

/* --- Responsive --- */
@media (max-width: 1024px) {
    .mega-menu { min-width: 500px; grid-template-columns: repeat(2, 1fr); }
    .footer-inner { grid-template-columns: 1fr 1fr 1fr; }
}
@media (max-width: 768px) {
    .header-nav { display: none; }
    .hero { padding: 50px 20px 30px; }
    .hero h1 { font-size: 2rem; }
    .tool-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
    .tool-card { padding: 20px 16px; }
    .chips { gap: 8px; }
    .chip { padding: 7px 14px; font-size: 0.8rem; }
    .footer-inner { grid-template-columns: 1fr; gap: 24px; }
    .mega-menu { display: none; }
}
@media (max-width: 480px) {
    .tool-grid { grid-template-columns: 1fr; }
}

/* --- Utility --- */
.hidden { display: none !important; }
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 32px; }