:root {
    --primary-color: #3b82f6;
    --primary-light: #93c5fd;
    --primary-dark: #2563eb;
    --bg-color: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-alt: #f1f5f9;
    --text-color: #0f172a;
    --text-light: #64748b;
    --border-color: #e2e8f0;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --radius: 16px;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.5);
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --bg-secondary: #1e293b;
    --bg-alt: #020617;
    --text-color: #f8fafc;
    --text-light: #94a3b8;
    --border-color: #334155;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: var(--font-sans);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
    -webkit-font-smoothing: antialiased;
}
a { color: var(--primary-color); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--primary-dark); }
ul { list-style: none; }
img, svg { max-width: 100%; height: auto; }

.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
.py-xl { padding-top: 5rem; padding-bottom: 5rem; }
.text-center { text-align: center; }
.mt-4 { margin-top: 1.5rem; }
.mb-4 { margin-bottom: 1.5rem; }

/* Header */
.header {
    position: sticky; top: 0; z-index: 100;
    background-color: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-color);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 80px; }
.logo { display: flex; align-items: center; gap: 0.75rem; font-weight: 800; font-size: 1.5rem; color: var(--text-color); letter-spacing: -0.025em; }
.nav-links { display: flex; gap: 2rem; }
.nav-links a { color: var(--text-color); font-weight: 500; font-size: 1rem; position: relative; }
.nav-links a:hover { color: var(--primary-color); }
.nav-links a::after { content: ''; position: absolute; bottom: -4px; left: 0; width: 0; height: 2px; background: var(--primary-color); transition: width 0.3s ease; }
.nav-links a:hover::after { width: 100%; }
.header-actions { display: flex; align-items: center; gap: 1rem; }
.mobile-menu-btn { display: none; background: none; border: none; color: var(--text-color); cursor: pointer; }

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 0.625rem 1.25rem; border-radius: 9999px; font-weight: 600; cursor: pointer; transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1); border: none; font-size: 1rem; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background-color: var(--primary-color); color: white; box-shadow: 0 4px 14px 0 rgba(59, 130, 246, 0.39); }
.btn-primary:hover { background-color: var(--primary-dark); box-shadow: 0 6px 20px rgba(59, 130, 246, 0.23); }
.btn-success { background-color: var(--success); color: white; box-shadow: 0 4px 14px 0 rgba(16, 185, 129, 0.39); }
.btn-success:hover { background-color: #059669; }
.btn-outline { background-color: transparent; border: 1.5px solid var(--border-color); color: var(--text-color); }
.btn-outline:hover { border-color: var(--primary-color); color: var(--primary-color); }
.btn-large { padding: 0.875rem 2rem; font-size: 1.125rem; }
.btn-icon { background: none; border: none; color: var(--text-color); cursor: pointer; display: flex; align-items: center; justify-content: center; width: 44px; height: 44px; border-radius: 50%; transition: background-color 0.2s; }
.btn-icon:hover { background-color: var(--bg-alt); }

/* Hero */
.hero { padding: 8rem 0; background: linear-gradient(180deg, var(--bg-color) 0%, var(--bg-alt) 100%); text-align: center; position: relative; overflow: hidden; }
.hero::before { content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%; background: radial-gradient(circle, var(--primary-light) 0%, transparent 40%); opacity: 0.1; z-index: 0; pointer-events: none; }
.hero .container { position: relative; z-index: 1; }
.hero h1 { font-size: 4.5rem; line-height: 1.1; margin-bottom: 1.5rem; font-weight: 800; letter-spacing: -0.04em; background: linear-gradient(to right, var(--text-color), var(--text-light)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-subtitle { font-size: 1.25rem; color: var(--text-light); max-width: 700px; margin: 0 auto 3rem; line-height: 1.8; }
.hero-cta { display: flex; gap: 1rem; justify-content: center; margin-bottom: 5rem; }
.hero-illustration { width: 100%; max-width: 900px; margin: 0 auto; box-shadow: var(--shadow-lg); border-radius: 24px; overflow: hidden; background: var(--bg-secondary); border: 1px solid var(--glass-border); padding: 1rem; }
.hero-illustration svg { border-radius: 16px; width: 100%; height: auto; }

/* Stats & Steps */
.stats-section { padding: 4rem 0; border-bottom: 1px solid var(--border-color); }
.stats-grid, .steps-grid { display: grid; gap: 2rem; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.stat-card { text-align: center; padding: 2.5rem 1rem; background: var(--bg-secondary); border-radius: var(--radius); border: 1px solid var(--border-color); transition: transform 0.3s; }
.stat-card:hover { transform: translateY(-5px); box-shadow: var(--shadow); }
.stat-card h2 { font-size: 3rem; color: var(--primary-color); font-weight: 800; letter-spacing: -0.02em; line-height: 1; margin-bottom: 0.5rem; }
.stat-card p { color: var(--text-light); font-weight: 500; }
.how-it-works { padding: 6rem 0; background-color: var(--bg-alt); }
.section-title { font-size: 2.5rem; font-weight: 800; text-align: center; margin-bottom: 4rem; letter-spacing: -0.025em; }
.step-card { text-align: center; padding: 2.5rem 2rem; background: var(--bg-secondary); border-radius: var(--radius); border: 1px solid var(--border-color); transition: transform 0.3s; }
.step-card:hover { transform: translateY(-5px); box-shadow: var(--shadow); }
.step-icon { width: 64px; height: 64px; border-radius: 20px; background: rgba(59, 130, 246, 0.1); color: var(--primary-color); display: flex; align-items: center; justify-content: center; font-size: 2rem; font-weight: 800; margin: 0 auto 1.5rem; }
.step-card h3 { font-size: 1.5rem; margin-bottom: 1rem; }
.step-card p { color: var(--text-light); }

/* SEO Tool */
.tool-container { max-width: 1000px; padding: 6rem 1.5rem; }
.tool-container h1 { font-size: 3rem; font-weight: 800; letter-spacing: -0.025em; margin-bottom: 2rem; }
.tool-input-section { background: var(--bg-secondary); padding: 3rem; border-radius: 24px; border: 1px solid var(--border-color); margin-top: 2rem; box-shadow: var(--shadow-lg); }
.tabs { display: flex; border-bottom: 1px solid var(--border-color); margin-bottom: 2.5rem; gap: 2rem; }
.tab-btn { background: none; border: none; padding: 1rem 0; color: var(--text-light); cursor: pointer; font-weight: 600; border-bottom: 2px solid transparent; font-size: 1.125rem; transition: color 0.2s; }
.tab-btn:hover { color: var(--text-color); }
.tab-btn.active { color: var(--primary-color); border-bottom-color: var(--primary-color); }
.input-group { display: flex; gap: 1rem; }
.form-control { flex: 1; padding: 1.25rem 1.5rem; border: 2px solid var(--border-color); border-radius: 12px; background: var(--bg-color); color: var(--text-color); font-size: 1.125rem; transition: all 0.2s; }
.form-control:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.15); }

a:focus-visible, button:focus-visible { outline: 2px solid var(--primary-color); outline-offset: 2px; border-radius: 4px; }

/* Report Styles */
.score-card { background: var(--bg-secondary); border-radius: 24px; padding: 4rem 2rem; text-align: center; border: 1px solid var(--border-color); box-shadow: var(--shadow-lg); margin-bottom: 3rem; }
.score-gauge { position: relative; width: 200px; height: 200px; margin: 0 auto 2rem; border-radius: 50%; background: conic-gradient(var(--success) 85%, var(--border-color) 0); display: flex; align-items: center; justify-content: center; box-shadow: inset 0 0 20px rgba(0,0,0,0.05); }
.score-gauge::before { content: ''; position: absolute; inset: 16px; background: var(--bg-secondary); border-radius: 50%; box-shadow: 0 4px 10px rgba(0,0,0,0.05); }
.score-value { position: relative; font-size: 4.5rem; font-weight: 800; color: var(--text-color); letter-spacing: -0.04em; }
.report-section { background: var(--bg-secondary); border-radius: var(--radius); border: 1px solid var(--border-color); margin-bottom: 2rem; overflow: hidden; box-shadow: var(--shadow-sm); }
.report-section-header { padding: 1.75rem 2rem; background: var(--bg-alt); border-bottom: 1px solid var(--border-color); display: flex; justify-content: space-between; align-items: center; }
.report-section-header h3 { font-size: 1.25rem; font-weight: 700; }
.badge { padding: 0.35rem 1rem; border-radius: 9999px; font-size: 0.875rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; }
.badge-success { background: rgba(16, 185, 129, 0.15); color: var(--success); }
.badge-warning { background: rgba(245, 158, 11, 0.15); color: var(--warning); }
.badge-danger { background: rgba(239, 68, 68, 0.15); color: var(--danger); }
.check-list { list-style: none; }
.check-item { padding: 1.5rem 2rem; border-bottom: 1px solid var(--border-color); display: flex; gap: 1.5rem; align-items: flex-start; }
.check-item:last-child { border-bottom: none; }
.check-item-title { font-weight: 700; margin-bottom: 0.35rem; display: flex; align-items: center; gap: 0.75rem; font-size: 1.125rem; }
.status-icon { width: 28px; height: 28px; border-radius: 50%; display: flex; align-items: center; justify-content: center; flex-shrink: 0; font-weight: bold; }
.status-success { background: rgba(16, 185, 129, 0.15); color: var(--success); }
.status-warning { background: rgba(245, 158, 11, 0.15); color: var(--warning); }
.status-danger { background: rgba(239, 68, 68, 0.15); color: var(--danger); }

/* Blog */
.blog-grid { display: grid; gap: 2.5rem; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); margin-top: 3rem; }
.blog-card { background: var(--bg-secondary); border-radius: var(--radius); overflow: hidden; border: 1px solid var(--border-color); transition: all 0.3s; display: flex; flex-direction: column; }
.blog-card:hover { transform: translateY(-8px); box-shadow: var(--shadow-lg); }
.blog-card-content { padding: 2rem; flex: 1; display: flex; flex-direction: column; }
.blog-card h3 { margin-bottom: 1rem; font-size: 1.5rem; font-weight: 700; line-height: 1.3; }
.blog-card h3 a { color: var(--text-color); }
.blog-card h3 a:hover { color: var(--primary-color); }
.blog-card p { color: var(--text-light); margin-bottom: 1.5rem; flex: 1; }
.blog-meta { font-size: 0.875rem; color: var(--text-light); font-weight: 500; display: flex; align-items: center; gap: 0.5rem; }
.blog-post { max-width: 800px; }
.blog-header { margin-bottom: 4rem; }
.blog-header h1 { font-size: 3.5rem; line-height: 1.2; font-weight: 800; letter-spacing: -0.025em; margin-bottom: 1rem; }
.prose { font-size: 1.125rem; line-height: 1.8; color: var(--text-color); }
.prose h2 { font-size: 2rem; font-weight: 700; margin: 3rem 0 1.5rem; letter-spacing: -0.02em; }
.prose h3 { font-size: 1.5rem; font-weight: 600; margin: 2rem 0 1rem; }
.prose p { margin-bottom: 1.5rem; color: var(--text-light); }
.prose ul { margin-bottom: 2rem; padding-left: 1.5rem; list-style-type: disc; color: var(--text-light); }
.prose li { margin-bottom: 0.5rem; }

/* Footer */
.footer { background: var(--bg-alt); padding: 6rem 0 2rem; border-top: 1px solid var(--border-color); margin-top: 6rem; }
.footer-grid { display: grid; gap: 4rem; grid-template-columns: 2fr 1fr 1fr 1fr; margin-bottom: 4rem; }
.footer-col h3 { font-size: 1.125rem; font-weight: 700; margin-bottom: 1.5rem; color: var(--text-color); }
.footer-col a { display: block; color: var(--text-light); margin-bottom: 0.75rem; font-weight: 500; }
.footer-col a:hover { color: var(--primary-color); }
.social-links { display: flex; gap: 1rem; margin-top: 1.5rem; }
.social-links a { display: flex; align-items: center; justify-content: center; width: 40px; height: 40px; border-radius: 50%; background: var(--bg-secondary); border: 1px solid var(--border-color); color: var(--text-light); transition: all 0.2s; }
.social-links a:hover { color: var(--primary-color); border-color: var(--primary-color); transform: translateY(-2px); }
.footer-bottom { border-top: 1px solid var(--border-color); padding-top: 2rem; text-align: center; color: var(--text-light); font-size: 0.875rem; font-weight: 500; }

/* Spinner */
.spinner { width: 48px; height: 48px; border: 4px solid var(--border-color); border-top-color: var(--primary-color); border-radius: 50%; animation: spin 1s cubic-bezier(0.55, 0.15, 0.45, 0.85) infinite; margin: 0 auto 1.5rem; }
@keyframes spin { to { transform: rotate(360deg); } }

/* Back to top */
#back-to-top { position: fixed; bottom: 2rem; right: 2rem; background: var(--primary-color); color: white; border: none; width: 56px; height: 56px; border-radius: 50%; cursor: pointer; display: none; align-items: center; justify-content: center; box-shadow: 0 10px 25px rgba(59, 130, 246, 0.5); z-index: 99; transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1); }
#back-to-top:hover { transform: translateY(-5px) scale(1.05); }

/* Utilities */
.shadow-lg { box-shadow: var(--shadow-lg); }
.rounded-xl { border-radius: 24px; }

/* Responsive */
@media (max-width: 1024px) {
    .hero h1 { font-size: 3.5rem; }
    .footer-grid { grid-template-columns: 1fr 1fr; gap: 3rem; }
}

@media (max-width: 768px) {
    .nav-links { display: none; position: absolute; top: 100%; left: 0; right: 0; background: var(--glass-bg); backdrop-filter: blur(16px); flex-direction: column; padding: 2rem; border-bottom: 1px solid var(--border-color); box-shadow: var(--shadow-lg); gap: 1.5rem; text-align: center; }
    .nav-links.active { display: flex; }
    .mobile-menu-btn { display: block; }
    .hero h1 { font-size: 2.5rem; }
    .hero-subtitle { font-size: 1.125rem; }
    .hero-cta { flex-direction: column; width: 100%; max-width: 300px; margin-left: auto; margin-right: auto; }
    .footer-grid { grid-template-columns: 1fr; gap: 2.5rem; text-align: center; }
    .social-links { justify-content: center; }
    .input-group { flex-direction: column; }
    .tool-input-section { padding: 1.5rem; }
    .score-value { font-size: 3.5rem; }
    .score-gauge { width: 160px; height: 160px; }
}