:root{--bg-gradient:linear-gradient(135deg,#f5f7fa 0%,#c3cfe2 100%);--aurora-gradient:linear-gradient(135deg,var(--color-primary)0%,var(--color-primary-700)100%);--card-hover-shadow:0 10px 25px -5px #0000001a,0 8px 10px -6px #0000001a;--radius-xl:1rem;--radius-2xl:1.5rem}.subject-topics-page{background:var(--bg-secondary);min-height:100vh;color:var(--text-primary);padding-bottom:4rem;font-family:Inter,system-ui,-apple-system,sans-serif}.topics-container{z-index:20;max-width:1200px;margin:0 auto;padding:0 1.5rem;position:relative}.topics-grid{grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:1.5rem;margin-top:2rem;display:grid}.topic-card{background:var(--bg-primary);border:1px solid var(--border-primary);border-radius:var(--radius-xl);flex-direction:column;height:100%;padding:1.5rem;text-decoration:none;transition:all .3s;animation:.6s ease-out slideUp;display:flex;position:relative}.topic-card:hover{box-shadow:var(--card-hover-shadow);border-color:var(--color-primary-200);transform:translateY(-4px)}.topic-card:before{content:"";background:var(--color-primary-500);border-top-left-radius:var(--radius-xl);border-bottom-left-radius:var(--radius-xl);opacity:0;width:4px;height:100%;transition:opacity .3s;position:absolute;top:0;left:0}.topic-card:hover:before{opacity:1}.topic-title{color:var(--text-primary);margin:0 0 1rem;font-size:1.125rem;font-weight:600;line-height:1.4}.topic-card:hover .topic-title{color:var(--color-primary-600)}.topic-meta{border-top:1px dashed var(--border-primary);color:var(--text-tertiary);justify-content:space-between;align-items:center;margin-top:auto;padding-top:1rem;font-size:.875rem;display:flex}.start-btn{background:var(--color-primary-50);color:var(--color-primary-600);border-radius:.5rem;padding:.25rem .75rem;font-size:.75rem;font-weight:600;transition:background .2s}.topic-card:hover .start-btn{background:var(--color-primary-600);color:#fff}@keyframes slideUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}.btn-back{color:var(--color-primary-600);margin-top:1.5rem;font-weight:600;text-decoration:none;display:inline-block}