*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --primary:#6366F1;--primary-dim:rgba(99,102,241,.12);
  --secondary:#818CF8;--accent:#F59E0B;--accent-dim:rgba(245,158,11,.12);
  --bg:#0A0A1F;--surface:#14143A;--surface2:#1E1E4A;
  --border:rgba(99,102,241,.1);--text:#E0E7FF;--text-dim:#A5B4FC;
  --radius:12px;--font:'Inter',system-ui,sans-serif;
  --transition:250ms ease;
}
html{font-size:16px;scroll-behavior:smooth}
body{background:var(--bg);color:var(--text);font-family:var(--font);line-height:1.6;min-height:100vh}
.header{position:sticky;top:0;z-index:100;backdrop-filter:blur(16px);background:rgba(10,10,31,.8);border-bottom:1px solid var(--border)}
.header-inner{max-width:800px;margin:0 auto;padding:.75rem 1.5rem;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:.75rem}
.logo{display:flex;align-items:center;gap:.5rem}
.logo-icon{font-size:1.25rem}
.logo h1{font-size:1.1rem;font-weight:700;background:linear-gradient(135deg,var(--primary),var(--secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.header-right{display:flex;gap:.5rem;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:.3rem;padding:.45rem .85rem;border:none;border-radius:8px;font-size:.8rem;font-weight:600;cursor:pointer;transition:all var(--transition);font-family:var(--font)}
.btn-sm{background:var(--surface2);color:var(--text-dim);border:1px solid var(--border)}
.btn-sm:hover{border-color:var(--primary);color:var(--primary)}
.main{max-width:800px;margin:0 auto;padding:1.5rem}
.glass-card{background:rgba(20,20,58,.6);backdrop-filter:blur(12px);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem;margin-bottom:1.25rem}
.section-title{font-size:.9rem;font-weight:700;margin-bottom:.75rem;display:flex;align-items:center;gap:.5rem}
.section-title::before{content:'';width:4px;height:18px;background:linear-gradient(to bottom,var(--primary),var(--secondary));border-radius:2px}
.stats-row{display:grid;grid-template-columns:repeat(4,1fr);gap:.75rem;margin-bottom:1.25rem}
.stat-card{background:rgba(20,20,58,.6);backdrop-filter:blur(12px);border:1px solid var(--border);border-radius:var(--radius);padding:.75rem;text-align:center}
.stat-val{font-size:1.4rem;font-weight:700;color:var(--primary)}
.stat-label{font-size:.65rem;color:var(--text-dim);text-transform:uppercase;letter-spacing:.5px;font-weight:600}
.deck-item{display:flex;justify-content:space-between;align-items:center;background:var(--surface2);border:1px solid var(--border);border-radius:8px;padding:.6rem .75rem;margin-bottom:.4rem;transition:border-color var(--transition)}
.deck-item:hover{border-color:var(--primary)}
.deck-info .di-name{font-size:.85rem;font-weight:700}
.deck-info .di-meta{font-size:.65rem;color:var(--text-dim)}
.deck-actions{display:flex;gap:.3rem}
.deck-actions button{background:none;border:none;cursor:pointer;font-size:.8rem;padding:.2rem .4rem}
.badge{font-size:.7rem;background:var(--primary-dim);color:var(--primary);padding:.2rem .6rem;border-radius:10px;font-weight:700}
.study-header{display:flex;align-items:center;gap:.75rem;margin-bottom:1rem}
.study-header .section-title{margin-bottom:0;flex:1}
.flashcard{perspective:800px;cursor:pointer;margin-bottom:1rem}
.flashcard .card-front,.flashcard .card-back{background:var(--surface2);border:1px solid var(--border);border-radius:var(--radius);padding:2rem;min-height:200px;display:flex;align-items:center;justify-content:center;font-size:1.1rem;text-align:center;transition:transform 300ms ease;backface-visibility:hidden}
.flashcard .card-back{display:none;color:var(--accent)}
.flashcard.flipped .card-front{display:none}
.flashcard.flipped .card-back{display:flex}
.grade-row{display:grid;grid-template-columns:repeat(4,1fr);gap:.5rem}
.grade-btn{padding:.6rem;font-weight:700;border-radius:8px;border:none;cursor:pointer;font-family:var(--font);font-size:.8rem;transition:all var(--transition)}
.grade-btn.again{background:rgba(239,68,68,.2);color:#EF4444}
.grade-btn.hard{background:rgba(245,158,11,.2);color:#F59E0B}
.grade-btn.good{background:rgba(16,185,129,.2);color:#10B981}
.grade-btn.easy{background:rgba(99,102,241,.2);color:#6366F1}
.grade-btn:hover{filter:brightness(1.3)}
.toast{position:fixed;bottom:2rem;left:50%;transform:translateX(-50%) translateY(100px);background:var(--surface2);color:var(--text);padding:.6rem 1.25rem;border-radius:var(--radius);font-size:.8rem;font-weight:500;border:1px solid var(--primary);box-shadow:0 8px 32px rgba(0,0,0,.4);transition:transform 300ms ease;z-index:9999;pointer-events:none}
.toast.show{transform:translateX(-50%) translateY(0)}
@media(max-width:600px){.stats-row{grid-template-columns:repeat(2,1fr)}.grade-row{grid-template-columns:repeat(2,1fr)}.main{padding:1rem}}