:root {
      --primary:#4F46E5;--primary-dark:#4338CA;--primary-light:#818CF8;--secondary:#0EA5E9;
      --success:#10B981;--warning:#F59E0B;--error:#EF4444;
      --gray-50:#F9FAFB;--gray-100:#F3F4F6;--gray-200:#E5E7EB;--gray-300:#D1D5DB;
      --gray-400:#9CA3AF;--gray-500:#6B7280;--gray-600:#4B5563;--gray-700:#374151;
      --gray-800:#1F2937;--gray-900:#111827;--white:#FFFFFF;
      --shadow-sm:0 1px 2px 0 rgb(0 0 0/.05);
      --shadow:0 1px 3px 0 rgb(0 0 0/.1),0 1px 2px -1px rgb(0 0 0/.1);
      --shadow-md:0 4px 6px -1px rgb(0 0 0/.1),0 2px 4px -2px rgb(0 0 0/.1);
      --shadow-lg:0 10px 15px -3px rgb(0 0 0/.1),0 4px 6px -4px rgb(0 0 0/.1);
      --shadow-xl:0 20px 25px -5px rgb(0 0 0/.1),0 8px 10px -6px rgb(0 0 0/.1);
      --radius-sm:6px;--radius:8px;--radius-md:12px;--radius-lg:16px;--radius-xl:24px;
    }
    *,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
    html{scroll-behavior:smooth}
    body{font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;background:var(--white);color:var(--gray-800);line-height:1.6;-webkit-font-smoothing:antialiased}

    /* -- Nav -- */
    .nav{position:fixed;top:0;left:0;right:0;z-index:100;background:rgba(255,255,255,.92);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border-bottom:1px solid var(--gray-200)}
    .nav-inner{max-width:1200px;margin:0 auto;padding:0 24px;height:64px;display:flex;align-items:center;justify-content:space-between}
    .nav-logo{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--gray-900)}
    .nav-logo-icon{width:34px;height:34px;background:linear-gradient(135deg,var(--primary),var(--secondary));border-radius:var(--radius);display:flex;align-items:center;justify-content:center;color:var(--white)}
    .nav-logo-icon svg{width:20px;height:20px}
    .nav-logo-text{font-size:1.05rem;font-weight:800;letter-spacing:-.03em}
    .nav-links{display:flex;align-items:center;gap:6px}
    .nav-link{text-decoration:none;padding:8px 14px;font-size:.875rem;font-weight:600;color:var(--gray-600);border-radius:var(--radius);transition:all .2s ease}
    .nav-link:hover{color:var(--gray-900);background:var(--gray-50)}
    .nav-link.active{color:var(--primary);background:rgba(79,70,229,.06)}
    .nav-cta{display:inline-flex;align-items:center;gap:6px;padding:8px 18px;font-size:.875rem;font-weight:700;color:var(--white);background:linear-gradient(135deg,var(--primary),var(--primary-dark));border:none;border-radius:var(--radius);cursor:pointer;text-decoration:none;transition:all .2s ease;box-shadow:0 2px 8px rgba(79,70,229,.25)}
    .nav-cta:hover{transform:translateY(-1px);box-shadow:0 4px 16px rgba(79,70,229,.35)}
    .nav-cta svg{width:15px;height:15px}
    @media(max-width:600px){.nav-links{gap:2px}.nav-link{padding:6px 8px;font-size:.78rem}.nav-cta{padding:7px 12px;font-size:.8rem}}

    /* -- Sections -- */
    .section{padding:100px 24px}
    .section:first-of-type{padding-top:140px}
    .section-inner{max-width:1100px;margin:0 auto}
    .section-alt{background:linear-gradient(180deg,var(--gray-50),var(--white))}
    .section-dark{background:linear-gradient(135deg,var(--gray-900),#1a1a2e);color:var(--white)}

    /* -- Hero -- */
    .hero{text-align:center;padding-top:140px;padding-bottom:80px}
    .hero-badge{display:inline-flex;align-items:center;gap:6px;background:rgba(79,70,229,.08);border:1px solid rgba(79,70,229,.2);color:var(--primary);padding:6px 16px;border-radius:30px;font-size:.8rem;font-weight:700;margin-bottom:24px}
    .hero-badge svg{width:14px;height:14px}
    .hero h1{font-size:clamp(2.2rem,5.5vw,3.8rem);font-weight:800;line-height:1.1;letter-spacing:-.04em;color:var(--gray-900);margin-bottom:20px}
    .hero h1 .gradient{background:linear-gradient(135deg,var(--primary),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
    .hero-sub{font-size:clamp(1rem,2vw,1.25rem);color:var(--gray-500);max-width:640px;margin:0 auto 36px;line-height:1.65}
    .hero-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}
    .hero-btn{display:inline-flex;align-items:center;gap:8px;padding:14px 32px;border-radius:var(--radius-md);font-size:1rem;font-weight:700;cursor:pointer;transition:all .25s ease;text-decoration:none;border:none}
    .hero-btn.primary{background:linear-gradient(135deg,var(--primary),var(--primary-dark));color:var(--white);box-shadow:0 4px 20px rgba(79,70,229,.35)}
    .hero-btn.primary:hover{transform:translateY(-2px);box-shadow:0 8px 30px rgba(79,70,229,.45)}
    .hero-btn.secondary{background:var(--white);color:var(--gray-700);border:1px solid var(--gray-300);box-shadow:var(--shadow)}
    .hero-btn.secondary:hover{border-color:var(--gray-400);box-shadow:var(--shadow-md);transform:translateY(-1px)}
    .hero-btn svg{width:18px;height:18px}
    .hero-stat-row{display:flex;justify-content:center;gap:40px;margin-top:48px;flex-wrap:wrap}
    .hero-stat{text-align:center}
    .hero-stat-num{font-size:1.8rem;font-weight:900;color:var(--gray-900);letter-spacing:-.03em}
    .hero-stat-label{font-size:.8rem;color:var(--gray-500);font-weight:600}

    /* -- Workflow -- */
    .workflow-title{text-align:center;margin-bottom:60px}
    .workflow-title h2{font-size:clamp(1.6rem,3.5vw,2.4rem);font-weight:800;color:var(--gray-900);letter-spacing:-.03em;margin-bottom:12px}
    .workflow-title p{font-size:1.05rem;color:var(--gray-500);max-width:520px;margin:0 auto}
    .workflow-steps{display:grid;grid-template-columns:repeat(5,1fr);gap:0;position:relative}
    .workflow-step{display:flex;flex-direction:column;align-items:center;text-align:center;padding:0 12px;position:relative}
    .workflow-step-num{width:48px;height:48px;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--secondary));color:var(--white);font-size:1.1rem;font-weight:800;display:flex;align-items:center;justify-content:center;margin-bottom:16px;position:relative;z-index:2;box-shadow:0 4px 14px rgba(79,70,229,.3)}
    .workflow-step-icon{width:56px;height:56px;border-radius:var(--radius-md);background:var(--gray-50);border:1px solid var(--gray-200);display:flex;align-items:center;justify-content:center;margin-bottom:12px;color:var(--primary)}
    .workflow-step-icon svg{width:26px;height:26px}
    .workflow-step h3{font-size:.95rem;font-weight:700;color:var(--gray-900);margin-bottom:4px}
    .workflow-step p{font-size:.82rem;color:var(--gray-500);line-height:1.5}
    .workflow-connector{position:absolute;top:24px;left:calc(50% + 24px);right:calc(-50% + 24px);height:2px;background:linear-gradient(90deg,var(--primary-light),var(--secondary));z-index:1}
    .workflow-step:last-child .workflow-connector{display:none}
    @media(max-width:800px){
      .workflow-steps{grid-template-columns:1fr;gap:32px}
      .workflow-connector{display:none}
    }

    /* -- Feature groups -- */
    .fg-header{text-align:center;margin-bottom:48px}
    .fg-header h2{font-size:clamp(1.6rem,3.5vw,2.4rem);font-weight:800;color:var(--gray-900);letter-spacing:-.03em;margin-bottom:12px}
    .fg-header p{font-size:1.05rem;color:var(--gray-500);max-width:560px;margin:0 auto}
    .fg-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
    @media(max-width:700px){.fg-grid{grid-template-columns:1fr}}
    .fg-card{border:1px solid var(--gray-200);border-radius:var(--radius-lg);padding:28px;background:var(--white);transition:all .3s ease;position:relative;overflow:hidden}
    .fg-card:hover{border-color:var(--gray-300);box-shadow:var(--shadow-lg);transform:translateY(-3px)}
    .fg-card::before{content:'';position:absolute;top:0;left:0;right:0;height:3px;background:linear-gradient(90deg,var(--primary),var(--secondary));opacity:0;transition:opacity .3s ease}
    .fg-card:hover::before{opacity:1}
    .fg-card-icon{width:48px;height:48px;border-radius:var(--radius-md);display:flex;align-items:center;justify-content:center;margin-bottom:16px;flex-shrink:0}
    .fg-card-icon svg{width:24px;height:24px}
    .fg-card-icon.purple{background:rgba(79,70,229,.1);color:var(--primary)}
    .fg-card-icon.blue{background:rgba(14,165,233,.1);color:var(--secondary)}
    .fg-card-icon.green{background:rgba(16,185,129,.1);color:var(--success)}
    .fg-card-icon.amber{background:rgba(245,158,11,.1);color:var(--warning)}
    .fg-card h3{font-size:1.05rem;font-weight:700;color:var(--gray-900);margin-bottom:6px}
    .fg-card p{font-size:.88rem;color:var(--gray-500);line-height:1.6}

    /* -- Study modes showcase -- */
    .modes-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
    @media(max-width:900px){.modes-grid{grid-template-columns:repeat(2,1fr)}}
    @media(max-width:500px){.modes-grid{grid-template-columns:1fr}}
    .mode-card{border:1px solid var(--gray-200);border-radius:var(--radius-lg);padding:24px 20px;text-align:center;background:var(--white);transition:all .3s ease;position:relative;overflow:hidden}
    .mode-card:hover{border-color:var(--primary-light);box-shadow:0 8px 30px rgba(79,70,229,.12);transform:translateY(-4px)}
    .mode-card-icon{width:56px;height:56px;border-radius:50%;margin:0 auto 14px;display:flex;align-items:center;justify-content:center}
    .mode-card-icon svg{width:28px;height:28px;color:var(--white)}
    .mode-card-icon.mc-purple{background:linear-gradient(135deg,var(--primary),var(--primary-dark))}
    .mode-card-icon.mc-blue{background:linear-gradient(135deg,#38BDF8,#0EA5E9)}
    .mode-card-icon.mc-green{background:linear-gradient(135deg,#34D399,#10B981)}
    .mode-card-icon.mc-amber{background:linear-gradient(135deg,#FBBF24,#F59E0B)}
    .mode-card h3{font-size:.95rem;font-weight:700;color:var(--gray-900);margin-bottom:4px}
    .mode-card p{font-size:.82rem;color:var(--gray-500);line-height:1.5}
    .mode-card-tag{display:inline-block;margin-top:10px;font-size:.7rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;padding:3px 10px;border-radius:20px}
    .mode-card-tag.tag-new{background:rgba(79,70,229,.1);color:var(--primary)}
    .mode-card-tag.tag-popular{background:rgba(16,185,129,.1);color:var(--success)}

    /* -- Time calculator -- */
    .calc-wrap{max-width:680px;margin:0 auto;text-align:center}
    .calc-card{background:var(--white);border:1px solid var(--gray-200);border-radius:var(--radius-xl);padding:40px;box-shadow:var(--shadow-lg)}
    .calc-card h3{font-size:1.1rem;font-weight:700;color:var(--gray-900);margin-bottom:20px}
    .calc-slider-row{display:flex;align-items:center;gap:16px;margin-bottom:8px}
    .calc-slider-label{font-size:.85rem;color:var(--gray-600);font-weight:600;min-width:180px;text-align:right}
    .calc-slider{flex:1;-webkit-appearance:none;appearance:none;height:6px;border-radius:3px;background:var(--gray-200);outline:none;cursor:pointer}
    .calc-slider::-webkit-slider-thumb{-webkit-appearance:none;width:22px;height:22px;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--secondary));cursor:pointer;box-shadow:0 2px 8px rgba(79,70,229,.3)}
    .calc-slider-val{min-width:40px;font-size:.95rem;font-weight:700;color:var(--gray-900);text-align:left}
    .calc-divider{height:1px;background:var(--gray-200);margin:24px 0}
    .calc-result{display:flex;justify-content:center;gap:40px;flex-wrap:wrap}
    .calc-result-item{text-align:center}
    .calc-result-num{font-size:2.2rem;font-weight:900;letter-spacing:-.03em}
    .calc-result-num.highlight{background:linear-gradient(135deg,var(--primary),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
    .calc-result-label{font-size:.78rem;color:var(--gray-500);font-weight:600;margin-top:2px}

    /* -- Comparison table -- */
    .comparison{max-width:780px;margin:0 auto}
    .comparison-table{width:100%;border-collapse:collapse;border-radius:var(--radius-lg);overflow:hidden;box-shadow:var(--shadow-lg)}
    .comparison-table th,.comparison-table td{padding:16px 20px;text-align:left;font-size:.9rem}
    .comparison-table thead th{background:var(--gray-900);color:var(--white);font-weight:700;font-size:.82rem;text-transform:uppercase;letter-spacing:.05em}
    .comparison-table thead th:first-child{border-top-left-radius:var(--radius-md)}
    .comparison-table thead th:last-child{border-top-right-radius:var(--radius-md)}
    .comparison-table tbody tr{border-bottom:1px solid var(--gray-100)}
    .comparison-table tbody tr:nth-child(even){background:var(--gray-50)}
    .comparison-table tbody td{color:var(--gray-700)}
    .comparison-table .col-task{font-weight:600;color:var(--gray-900)}
    .comparison-table .col-manual{color:var(--error);font-weight:600}
    .comparison-table .col-lp{color:var(--success);font-weight:700}
    .comparison-table .col-lp svg{width:16px;height:16px;vertical-align:middle;margin-right:4px;color:var(--success)}

    /* -- CTA -- */
    .cta-section{text-align:center;padding:80px 24px 100px}
    .cta-card{max-width:700px;margin:0 auto;padding:60px 40px;background:linear-gradient(135deg,var(--primary),var(--primary-dark));border-radius:var(--radius-xl);box-shadow:0 20px 60px rgba(79,70,229,.3);position:relative;overflow:hidden}
    .cta-card::before{content:'';position:absolute;top:-50%;right:-30%;width:300px;height:300px;border-radius:50%;background:rgba(255,255,255,.06)}
    .cta-card::after{content:'';position:absolute;bottom:-40%;left:-20%;width:250px;height:250px;border-radius:50%;background:rgba(255,255,255,.04)}
    .cta-card h2{font-size:clamp(1.5rem,3vw,2rem);font-weight:800;color:var(--white);margin-bottom:12px;position:relative;z-index:1}
    .cta-card p{font-size:1.05rem;color:rgba(255,255,255,.8);margin-bottom:28px;position:relative;z-index:1}
    .cta-btn{display:inline-flex;align-items:center;gap:8px;padding:16px 36px;font-size:1.05rem;font-weight:700;border:none;border-radius:var(--radius-md);cursor:pointer;transition:all .25s ease;background:var(--white);color:var(--primary);text-decoration:none;position:relative;z-index:1;box-shadow:0 4px 20px rgba(0,0,0,.15)}
    .cta-btn:hover{transform:translateY(-2px);box-shadow:0 8px 30px rgba(0,0,0,.25)}
    .cta-btn svg{width:18px;height:18px}

    /* -- Footer -- */
    .footer{background:var(--gray-900);color:var(--gray-400);padding:40px 24px;text-align:center;font-size:.85rem}
    .footer a{color:var(--gray-300);text-decoration:none}
    .footer a:hover{color:var(--white)}

    /* -- Animations -- */
    .reveal{opacity:0;transform:translateY(30px);transition:all .6s ease-out}
    .reveal.visible{opacity:1;transform:translateY(0)}
    @media(prefers-reduced-motion:reduce){.reveal{opacity:1;transform:none;transition:none}}