*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{-webkit-text-size-adjust:100%;-moz-text-size-adjust:100%;text-size-adjust:100%}
body{margin:0}
img,picture,video,canvas,svg{display:block;max-width:100%}
input,button,textarea,select{font:inherit;color:inherit}
a{color:inherit;text-decoration:none}
table{border-collapse:collapse;border-spacing:0}
ol,ul{list-style:none}
:root{--bg:#0b1120;--surface:#151d32;--surface2:#1e2a45;--surface3:#28365a;--text:#e2e8f0;--muted:#8495b8;--accent:#3b82f6;--accent-hover:#2563eb;--accent-glow:rgba(59,130,246,0.25);--danger:#ef4444;--success:#22c55e;--radius:10px;--radius-sm:6px;--max-w:1100px;--card-w:280px;--header-h:64px;--transition:.2s}
body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Helvetica Neue',Arial,sans-serif;background:var(--bg);color:var(--text);min-height:100vh;line-height:1.5;-webkit-font-smoothing:antialiased}

/* ── Top Banner ── */
.top-banner{position:fixed;top:0;left:0;right:0;height:60px;z-index:101;display:flex;align-items:center;justify-content:center;background:#0b1120;border-bottom:1px solid rgba(255,255,255,0.06)}

/* ── Header ── */
.header{position:fixed;top:60px;left:0;right:0;height:var(--header-h);background:linear-gradient(180deg,rgba(21,29,50,0.95),rgba(11,17,32,0.9));backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border-bottom:1px solid var(--surface2);z-index:100;display:flex;align-items:center;padding:0 24px}
.header::before{content:'';position:absolute;top:0;left:0;right:0;height:2px;background:linear-gradient(90deg,var(--accent),#8b5cf6,#ec4899)}
.header-inner{width:100%;max-width:var(--max-w);margin:0 auto;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:0 4px}
.header-brand{font-size:clamp(.75rem,2.5vw,1.35rem);font-weight:800;color:#fff;letter-spacing:-.02em;white-space:nowrap;background:linear-gradient(135deg,#60a5fa,#a78bfa);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;flex-shrink:0}
.nav-links{display:flex;align-items:center;gap:0;background:rgba(59,130,246,0.08);border-radius:var(--radius-sm);padding:2px;border:1px solid rgba(59,130,246,0.12)}
.nav-link{padding:8px 10px;font-size:.9rem;font-weight:700;color:#94a3b8;cursor:default;border-radius:4px;transition:all var(--transition);letter-spacing:.01em;text-align:center;line-height:1.4;white-space:nowrap}
.nav-link:nth-child(1){color:#60a5fa}
.nav-link:nth-child(2){color:#a78bfa}
.nav-link:nth-child(3){color:#f472b6}
.nav-link:hover{filter:brightness(1.3);background:rgba(255,255,255,0.06)}
.nav-link-auth{font-weight:800 !important;cursor:pointer !important;color:#34d399 !important}
.nav-link-auth:last-child{color:#fbbf24 !important;background:rgba(251,191,36,0.1);border-radius:4px}
.header-actions{display:flex;gap:10px}

/* ── Buttons ── */
.btn{display:inline-flex;align-items:center;justify-content:center;padding:9px 20px;border:none;border-radius:var(--radius-sm);font-size:.875rem;font-weight:600;cursor:pointer;transition:background var(--transition),opacity var(--transition),box-shadow var(--transition);white-space:nowrap;line-height:1.4}
.btn-primary{background:var(--accent);color:#fff}
.btn-primary:hover{background:var(--accent-hover);box-shadow:0 0 20px var(--accent-glow)}
.btn-secondary{background:var(--surface2);color:var(--text)}
.btn-secondary:hover{background:var(--surface3)}
.btn-danger{background:var(--danger);color:#fff}
.btn-danger:hover{opacity:.9}
.btn-outline{background:transparent;border:1px solid var(--surface2);color:var(--text)}
.btn-outline:hover{border-color:var(--accent);color:var(--accent)}
.btn-ghost{background:transparent;color:var(--muted)}
.btn-ghost:hover{color:var(--text)}
.btn-sm{padding:6px 14px;font-size:.8rem}
.btn:disabled{opacity:.4;cursor:not-allowed;box-shadow:none}


/* ── Landing Page ── */
.hero{min-height:100vh;display:flex;flex-direction:column;padding:calc(60px + var(--header-h) + 24px) 24px 60px;background:radial-gradient(ellipse 600px 400px at 50% 30%,rgba(59,130,246,0.08),transparent)}
.hero-content{max-width:600px;margin:0 auto;display:flex;align-items:center;width:100%}
.hero-cta{width:100%;text-align:center}
.hero-tagline{font-size:clamp(1.5rem,3vw,2.2rem);font-weight:800;margin-bottom:6px;letter-spacing:.04em;background:linear-gradient(135deg,#3b82f6,#a78bfa,#ec4899);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero-tagline strong{font-size:clamp(1.8rem,4vw,3rem);font-weight:900;background:linear-gradient(135deg,#f59e0b,#ef4444);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.btn-upload-create{display:inline-block;padding:18px 48px;border:none;border-radius:14px;font-size:1.2rem;font-weight:700;cursor:pointer;letter-spacing:.03em;background:linear-gradient(135deg,#3b82f6,#8b5cf6);color:#fff;box-shadow:0 6px 30px rgba(59,130,246,0.35);transition:all .3s;margin:8px 0 24px}
.btn-upload-create:hover{transform:translateY(-3px);box-shadow:0 10px 50px rgba(59,130,246,0.5);background:linear-gradient(135deg,#2563eb,#7c3aed)}
.hero-cta h1{font-size:clamp(2rem,4vw,3rem);font-weight:800;line-height:1.15;letter-spacing:-.03em;margin-bottom:8px}
.hero-steps{font-size:.95rem;color:var(--muted);margin-bottom:20px;letter-spacing:.01em}
.hero-buttons{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}


.features{max-width:var(--max-w);margin:0 auto;padding:80px 24px;display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:20px}
.feature-card{background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius);padding:28px;transition:border-color var(--transition),transform var(--transition)}
.feature-card:hover{border-color:var(--accent);transform:translateY(-2px)}
.feature-icon{width:40px;height:40px;border-radius:10px;background:var(--accent-glow);display:flex;align-items:center;justify-content:center;font-size:1.25rem;margin-bottom:16px}
.feature-card h3{font-size:1rem;font-weight:600;margin-bottom:6px}
.feature-card p{font-size:.875rem;color:var(--muted);line-height:1.6}



/* ── Main App Wrapper ── */
.app{max-width:var(--max-w);margin:0 auto;padding:calc(var(--header-h) + 60px + 24px) 24px 40px;width:100%}

/* ── Auth Cards ── */
.auth-card{max-width:420px;margin:60px auto;background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius);padding:32px}
.auth-card h1{font-size:1.5rem;font-weight:700;margin-bottom:4px}
.auth-card p.sub{color:var(--muted);font-size:.875rem;margin-bottom:24px}
.form-group{margin-bottom:16px}
.form-group label{display:block;font-size:.8rem;font-weight:500;color:var(--muted);margin-bottom:5px;text-transform:uppercase;letter-spacing:.04em}
.form-group input,.form-group select{width:100%;padding:10px 12px;border:1px solid var(--surface2);border-radius:var(--radius-sm);background:var(--bg);color:var(--text);font-size:.9rem;outline:none;transition:border-color var(--transition)}
.form-group input:focus,.form-group select:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-glow)}
.form-group select option{background:var(--surface2);color:var(--text)}
.form-error{color:var(--danger);font-size:.8rem;margin-top:4px}
.form-footer{text-align:center;margin-top:16px;font-size:.85rem;color:var(--muted)}
.form-footer .link{color:var(--accent);cursor:pointer;font-weight:500}
.form-footer .link:hover{text-decoration:underline}

/* ── Dashboard / Library ── */
.page-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px;flex-wrap:wrap;gap:12px}
.page-header h1{font-size:1.5rem;font-weight:700}
.page-header p{color:var(--muted);font-size:.875rem}

.set-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(var(--card-w),1fr));gap:16px}
.set-card{background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius);padding:20px;cursor:pointer;transition:border-color var(--transition),transform var(--transition);position:relative}
.set-card:hover{border-color:var(--accent);transform:translateY(-2px)}
.set-card h3{font-size:1rem;font-weight:600;margin-bottom:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.set-card p{font-size:.8rem;color:var(--muted);margin-bottom:12px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.set-meta{display:flex;align-items:center;gap:12px;font-size:.75rem;color:var(--muted)}
.set-meta span{display:flex;align-items:center;gap:4px}
.empty-state{text-align:center;padding:60px 24px;color:var(--muted)}
.empty-state h2{font-size:1.25rem;margin-bottom:8px;color:var(--text)}
.empty-state p{margin-bottom:20px}

/* ── Modal / Overlay ── */
.overlay{position:fixed;inset:0;background:rgba(0,0,0,0.6);z-index:200;display:flex;align-items:center;justify-content:center;padding:24px}
.modal{background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius);padding:28px;width:100%;max-width:480px;max-height:85vh;overflow-y:auto}
.modal h2{font-size:1.25rem;font-weight:700;margin-bottom:16px}
.modal-actions{display:flex;gap:10px;margin-top:20px;justify-content:flex-end}
.modal-actions .btn{flex:1}

/* ── Set Detail / Cards ── */
.set-detail-header{margin-bottom:24px}
.set-detail-header h1{font-size:1.5rem;font-weight:700;margin-bottom:4px}
.set-detail-header p{color:var(--muted);font-size:.875rem}
.card-list{display:flex;flex-direction:column;gap:10px}
.card-item{background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius-sm);padding:16px 20px;display:flex;gap:16px;align-items:flex-start}
.card-item .front{flex:1;font-weight:600}
.card-item .back{flex:1;color:var(--muted)}
.card-item .divider{width:1px;background:var(--surface2);align-self:stretch;margin:0 4px}
.add-card-form{display:grid;grid-template-columns:1fr 1fr auto;gap:10px;margin-top:16px;align-items:end}
.add-card-form .form-group{margin-bottom:0}

/* ── Convert to Flashcards ── */
.convert-page{max-width:600px;margin:0 auto;padding-top:20px}
.convert-card{background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius);padding:32px}
.convert-card h1{font-size:1.5rem;font-weight:700;margin-bottom:4px}
.convert-card p.sub{color:var(--muted);font-size:.875rem;margin-bottom:24px}
.convert-card form{position:relative}
.convert-card textarea{width:100%;padding:10px 12px;border:1px solid var(--surface2);border-radius:var(--radius-sm);background:var(--bg);color:var(--text);font-size:.9rem;outline:none;transition:border-color var(--transition);font-family:inherit}
.convert-card textarea:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-glow)}

.upload-area{border:2px dashed var(--surface2);border-radius:var(--radius);padding:40px 24px;text-align:center;cursor:pointer;transition:all var(--transition);margin-bottom:16px}
.upload-area:hover{border-color:var(--accent);background:rgba(59,130,246,0.04)}
.upload-icon{font-size:2.5rem;margin-bottom:8px}
.page-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:16px;margin-bottom:12px}
.page-thumb{background:var(--surface);border:2px solid var(--surface2);border-radius:var(--radius-sm);overflow:hidden;cursor:pointer;transition:all var(--transition);position:relative}
.page-thumb:hover{border-color:var(--accent)}
.page-thumb.selected{border-color:var(--accent);box-shadow:0 0 12px var(--accent-glow)}
.page-num{text-align:center;font-size:.75rem;color:var(--muted);padding:6px;font-weight:600}
.page-check{position:absolute;top:4px;right:4px;width:22px;height:22px;border-radius:50%;background:var(--accent);color:#fff;display:flex;align-items:center;justify-content:center;font-size:.75rem;font-weight:700;box-shadow:0 2px 8px rgba(0,0,0,0.3)}
.page-bar-wrap{position:sticky;top:calc(60px + var(--header-h) + 8px);z-index:10;background:var(--bg);border-radius:var(--radius-sm);margin-bottom:12px}
.page-bar{display:flex;justify-content:space-between;align-items:center;background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius-sm) var(--radius-sm) 0 0;padding:8px 12px}

@media(max-width:600px){
.convert-card{padding:24px}
}

/* ── Tier / Premium ── */
.tier-bar{display:flex;align-items:center;justify-content:space-between;background:var(--surface);border:1px solid var(--surface2);border-radius:var(--radius-sm);padding:10px 16px;margin-bottom:16px;flex-wrap:wrap;gap:8px}
.tier-info{display:flex;align-items:center;gap:10px}
.user-badge{font-size:.85rem;display:flex;align-items:center;gap:6px}
.tier-badge{font-size:.65rem;font-weight:700;padding:2px 8px;border-radius:10px;letter-spacing:.04em}
.tier-free{background:var(--surface2);color:var(--muted)}
.tier-paid{background:rgba(34,197,94,0.15);color:var(--success)}
.upgrade-notice{background:linear-gradient(135deg,rgba(59,130,246,0.1),rgba(59,130,246,0.05));border:1px solid var(--accent);border-radius:var(--radius-sm);padding:14px 18px;margin-bottom:16px;text-align:center}
.upgrade-notice p{font-size:.85rem;color:var(--muted)}
.upgrade-notice .link{color:var(--accent);font-weight:600}
.enhance-btn{margin-top:8px;width:100%}

/* ── Enhance Modal ── */
.enhance-modal{max-width:560px}
.enhance-list{display:flex;flex-direction:column;gap:10px}
.enhance-item{background:var(--surface2);border-radius:var(--radius-sm);padding:12px 16px;font-size:.875rem;line-height:1.5;color:var(--text)}

/* ── Utility ── */
.mt-2{margin-top:8px}
.mt-4{margin-top:16px}
.text-center{text-align:center}
.flex{display:flex}
.flex-wrap{flex-wrap:wrap}
.gap-2{gap:8px}
.gap-4{gap:16px}
.items-center{align-items:center}
.justify-between{justify-content:space-between}

@media(max-width:600px){
:root{--header-h:56px;--card-w:100%}
.header{padding:0 12px;height:auto;min-height:var(--header-h)}
.header-inner{flex-wrap:nowrap;gap:8px;padding:0 2px}
.header-brand{display:none}
.nav-links{flex-wrap:nowrap;gap:0;padding:2px;justify-content:flex-start;overflow-x:auto;scrollbar-width:none}
.nav-link{padding:4px 8px;font-size:.7rem;white-space:nowrap;line-height:1.2}
.nav-link-auth{font-size:.7rem !important;padding:4px 8px !important}
.header-actions{margin-left:auto}
.app{padding:calc(var(--header-h) + 60px + 16px) 16px 24px}
.hero{padding:calc(60px + var(--header-h) + 16px) 16px 30px}
.features{padding:40px 16px;grid-template-columns:1fr}
.auth-card{margin:30px auto;padding:24px}
.feature-card{padding:20px}
.hero-buttons{flex-direction:column;width:100%}
.hero-buttons .btn{width:100%}
.page-grid{grid-template-columns:repeat(auto-fill,minmax(100px,1fr));gap:8px}
.add-card-form{grid-template-columns:1fr}
.card-item{flex-direction:column;gap:8px}
.card-item .divider{display:none}
.modal{padding:20px}
.tier-bar{flex-direction:column;align-items:stretch;text-align:center}
.tier-info{justify-content:center}
}