:root{--bg-color: #f8fafc;--card-bg: #ffffff;--card-border: #e2e8f0;--text-main: #0f172a;--text-muted: #64748b;--primary: #2563eb;--primary-hover: #1d4ed8;--accent: #7c3aed;--success: #10b981;--warning: #f59e0b;--danger: #ef4444;--font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;--shadow-sm: 0 1px 3px rgba(0, 0, 0, .05);--shadow-md: 0 4px 16px rgba(0, 0, 0, .06);--shadow-lg: 0 10px 30px rgba(0, 0, 0, .08)}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-color);color:var(--text-main);font-family:var(--font-family);line-height:1.6;min-height:100vh;-webkit-font-smoothing:antialiased;overflow-x:hidden}.navbar{position:sticky;top:0;z-index:100;background:#fffffff2;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);border-bottom:1px solid var(--card-border);box-shadow:var(--shadow-sm)}.nav-container{max-width:1280px;margin:0 auto;padding:16px 24px;display:flex;align-items:center;justify-content:space-between}.logo-brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--text-main);font-weight:800;font-size:20px;letter-spacing:-.5px}.logo-icon{width:36px;height:36px;background:linear-gradient(135deg,var(--primary),var(--accent));border-radius:10px;display:flex;align-items:center;justify-content:center;color:#fff;font-weight:900;box-shadow:0 4px 12px #2563eb4d}.mobile-toggle-btn{display:none;background:none;border:none;color:var(--text-main);cursor:pointer;padding:4px}.nav-links{display:flex;align-items:center;gap:8px;list-style:none}.nav-link{color:var(--text-muted);text-decoration:none;padding:8px 16px;border-radius:8px;font-size:14px;font-weight:600;transition:all .2s ease}.nav-link:hover,.nav-link.active{color:var(--primary);background:#2563eb14}.nav-btn-profile{display:flex;align-items:center;gap:10px;background:#2563eb14;border:1px solid rgba(37,99,235,.2);padding:6px 16px 6px 8px;border-radius:9999px;color:var(--primary);text-decoration:none;font-weight:700;font-size:14px;transition:all .2s ease}.nav-btn-profile:hover{background:#2563eb26;border-color:var(--primary)}.avatar-badge{width:28px;height:28px;background:linear-gradient(135deg,var(--success),#059669);border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:800;font-size:12px;color:#fff}.mobile-auth-slot{display:none}.desktop-auth-slot{display:block}.btn-primary{background:linear-gradient(135deg,var(--primary),var(--accent));color:#fff;border:none;padding:10px 20px;border-radius:10px;font-weight:600;font-size:14px;cursor:pointer;display:inline-flex;align-items:center;gap:8px;transition:all .2s ease;box-shadow:0 4px 14px #2563eb40}.btn-primary:hover{transform:translateY(-1px);box-shadow:0 6px 18px #2563eb59}.btn-secondary{background:#f1f5f9;border:1px solid #cbd5e1;color:#334155;padding:10px 20px;border-radius:10px;font-weight:600;font-size:14px;cursor:pointer;transition:all .2s ease}.btn-secondary:hover{background:#e2e8f0;color:#0f172a}.container{max-width:1280px;margin:0 auto;padding:32px 24px}.hero{text-align:center;padding:60px 20px;background:radial-gradient(circle at top center,rgba(37,99,235,.08),transparent 70%)}.hero-title{font-size:clamp(28px,5vw,48px);font-weight:900;letter-spacing:-1px;margin-bottom:16px;background:linear-gradient(135deg,#0f172a,#2563eb);-webkit-background-clip:text;-webkit-text-fill-color:transparent}.hero-subtitle{font-size:clamp(15px,2.5vw,18px);color:var(--text-muted);max-width:680px;margin:0 auto 32px}.hero-buttons{display:flex;gap:16px;justify-content:center}.hero-stats-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:20px;margin-top:40px}.stat-card{background:var(--card-bg);border:1px solid var(--card-border);padding:24px;border-radius:16px;text-align:center;box-shadow:var(--shadow-md)}.stat-value{font-size:32px;font-weight:900;color:var(--text-main);margin-bottom:4px}.stat-label{font-size:14px;color:var(--text-muted);font-weight:600}.roadmap-controls{display:flex;flex-wrap:wrap;gap:16px;align-items:center;justify-content:space-between;margin-bottom:24px;background:var(--card-bg);padding:16px 20px;border-radius:14px;border:1px solid var(--card-border);box-shadow:var(--shadow-sm)}.search-input{background:#f8fafc;border:1px solid #cbd5e1;color:var(--text-main);padding:10px 16px;border-radius:8px;font-size:14px;min-width:260px;outline:none}.search-input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #2563eb26}.week-accordion{background:var(--card-bg);border:1px solid var(--card-border);border-radius:14px;margin-bottom:16px;overflow:hidden;box-shadow:var(--shadow-sm)}.week-header{padding:18px 24px;display:flex;align-items:center;justify-content:space-between;cursor:pointer;-webkit-user-select:none;user-select:none;background:#fff;transition:background .2s ease}.week-header:hover{background:#f8fafc}.week-title{font-size:18px;font-weight:700;color:var(--text-main);display:flex;align-items:center;gap:12px}.problem-row{display:flex;align-items:center;justify-content:space-between;padding:14px 24px;border-top:1px solid var(--card-border);background:#fff;transition:background .15s ease}.problem-row:hover{background:#f8fafc}.problem-left{display:flex;align-items:center;gap:16px;flex:1}.checkbox-custom{width:20px;height:20px;cursor:pointer;accent-color:var(--success)}.problem-title{font-size:15px;font-weight:600;color:var(--text-main);text-decoration:none}.problem-title:hover{color:var(--primary)}.badge{padding:4px 10px;border-radius:6px;font-size:12px;font-weight:700;text-transform:uppercase}.badge-easy{background:#d1fae5;color:#047857}.badge-medium{background:#fef3c7;color:#b45309}.badge-hard{background:#fee2e2;color:#b91c1c}.profile-card-header{background:var(--card-bg);border:1px solid var(--card-border);border-radius:20px;overflow:hidden;margin-bottom:32px;box-shadow:var(--shadow-md)}.profile-cover{height:140px;background:linear-gradient(135deg,#2563eb,#7c3aed,#059669)}.profile-user-info-bar{padding:0 32px 24px;display:flex;align-items:flex-start;justify-content:space-between;margin-top:-48px}.user-avatar-circle{width:96px;height:96px;background:linear-gradient(135deg,var(--primary),var(--accent));border:4px solid #ffffff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:36px;font-weight:900;color:#fff;box-shadow:var(--shadow-lg);flex-shrink:0}.user-details{margin-top:12px}.user-details h1{font-size:26px;font-weight:800;color:var(--text-main)}.user-details p{color:var(--text-muted);font-size:14px}.heatmap-container{background:var(--card-bg);border:1px solid var(--card-border);padding:24px;border-radius:16px;margin-bottom:32px;box-shadow:var(--shadow-md)}.heatmap-grid-scroll{overflow-x:auto;padding-bottom:12px}.heatmap-grid{display:grid;grid-template-rows:repeat(7,14px);grid-auto-flow:column;grid-auto-columns:14px;gap:4px;min-width:720px}.heatmap-day{width:14px;height:14px;border-radius:3px;background:#ebedf0;position:relative}.heatmap-day.level-1{background:#9be9a8}.heatmap-day.level-2{background:#40c463}.heatmap-day.level-3{background:#30a14e}.heatmap-day.level-4{background:#216e39}.modal-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#0f172a80;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);z-index:1000;display:flex;align-items:center;justify-content:center;padding:20px}.modal-card{background:#fff;border:1px solid var(--card-border);width:92%;max-width:440px;border-radius:18px;padding:28px;box-shadow:var(--shadow-lg)}.form-group{margin-bottom:16px}.form-label{display:block;font-size:13px;font-weight:600;color:var(--text-muted);margin-bottom:6px}.form-input{width:100%;background:#f8fafc;border:1px solid #cbd5e1;padding:12px 14px;border-radius:8px;color:var(--text-main);font-size:14px;outline:none}.form-input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #2563eb26}@media(max-width:768px){.nav-container{padding:12px 16px}.mobile-toggle-btn{display:block}.desktop-auth-slot{display:none}.nav-links{position:absolute;top:100%;left:0;right:0;background:#fff;border-bottom:1px solid var(--card-border);flex-direction:column;padding:16px;gap:12px;display:none;box-shadow:var(--shadow-md)}.nav-links.open{display:flex}.mobile-auth-slot{display:block;width:100%;margin-top:8px}.mobile-auth-slot .btn-primary,.mobile-auth-slot .nav-btn-profile{width:100%;justify-content:center}.container{padding:20px 16px}.hero{padding:36px 12px}.hero-buttons{flex-direction:column;width:100%}.hero-buttons .btn-primary,.hero-buttons .btn-secondary{width:100%;justify-content:center}.hero-stats-grid{grid-template-columns:1fr 1fr;gap:12px}.roadmap-controls{flex-direction:column;align-items:stretch}.search-input{min-width:100%}.week-header{padding:14px 16px;flex-direction:column;align-items:flex-start;gap:8px}.problem-row{padding:12px 16px;flex-direction:column;align-items:flex-start;gap:12px}.problem-left{width:100%}.profile-user-info-bar{padding:0 16px 20px;flex-direction:column;gap:16px;margin-top:-40px}.user-avatar-circle{width:80px;height:80px;font-size:30px}.profile-card-header .btn-secondary{width:100%;justify-content:center}}@media(max-width:480px){.hero-stats-grid{grid-template-columns:1fr}}