@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap");:root{--font-sans:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;--font-mono:"JetBrains Mono",monospace;--bg-primary:#f5f5f7;--bg-card:#fff;--bg-card-hover:#fafafa;--bg-sidebar:#f0f0f5;--bg-input:#eef0f3;--bg-modal:#fff;--text-primary:#1d1d1f;--text-secondary:#86868b;--text-tertiary:#a1a1a6;--border-color:#e0e0e5;--border-focus:orange;--accent:orange;--accent-hover:#ff9000;--accent-light:rgba(255,165,0,.12);--accent-text:#fff;--success:#34c759;--danger:#ff3b30;--danger-light:rgba(255,59,48,.12);--shadow-sm:none;--shadow-md:none;--shadow-lg:none;--radius-sm:10px;--radius-md:16px;--radius-lg:24px}[data-theme=dark]{--bg-primary:#000;--bg-card:#1c1c1e;--bg-card-hover:#262628;--bg-sidebar:#141416;--bg-input:#2c2c2e;--bg-modal:#1c1c1e;--text-primary:#f5f5f7;--text-secondary:#98989d;--text-tertiary:#6e6e73;--border-color:#333336;--shadow-sm:none;--shadow-md:none;--shadow-lg:none}*{box-sizing:border-box;margin:0;padding:0;-webkit-font-smoothing:antialiased;box-shadow:none!important;text-shadow:none!important}body{font-family:var(--font-sans);background-color:var(--bg-primary);color:var(--text-primary);min-height:100vh;overflow-x:hidden;transition:background-color .3s ease,color .3s ease}.app-container{display:flex;flex-direction:column;min-height:100vh}.app-header{height:64px;padding:0 24px;justify-content:space-between;background:var(--bg-card);border-bottom:1px solid var(--border-color);position:-webkit-sticky;position:sticky;top:0;z-index:100}.app-header,.header-brand{display:flex;align-items:center}.header-brand{gap:12px}.brand-logo{width:38px;height:38px;border-radius:12px;background:var(--accent);display:flex;align-items:center;justify-content:center;color:#fff}.brand-titles h1{font-size:1.15rem;font-weight:700;letter-spacing:-.02em}.brand-titles .subtitle{font-size:.75rem;color:var(--text-secondary);display:block}.header-actions{display:flex;align-items:center;gap:10px}.card-counter-badge{display:flex;align-items:center;gap:6px;padding:6px 12px;background:var(--accent-light);color:var(--accent);border-radius:20px;font-size:.82rem;font-weight:600}.main-layout{display:flex;flex:1 1;max-width:1600px;margin:0 auto;width:100%}.category-sidebar{width:320px;background:var(--bg-sidebar);border-right:1px solid var(--border-color);display:flex;flex-direction:column;padding:20px 16px}.sidebar-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;padding:0 4px}.sidebar-title-group h3{font-size:1.05rem;font-weight:600}.badge-subtle{font-size:.75rem;color:var(--text-tertiary)}.category-tree-container{display:flex;flex-direction:column;gap:2px;overflow-y:auto}.category-item-row{display:flex;align-items:center;gap:8px;padding:8px 10px;border-radius:var(--radius-sm);cursor:pointer;-webkit-user-select:none;-moz-user-select:none;user-select:none;transition:all .15s ease;color:var(--text-primary);font-size:.9rem;position:relative}.category-item-row:hover{background:hsla(0,0%,50%,.1)}.category-item-row.selected{background:var(--accent-light);color:var(--accent);font-weight:600}.root-all-row{margin-bottom:4px;font-weight:500}.tree-divider{height:1px;background:var(--border-color);margin:8px 0}.cat-icon-badge{display:flex;align-items:center;justify-content:center;width:24px;height:24px;border-radius:6px;color:inherit}.cat-name{flex:1 1;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.cat-card-count{font-size:.75rem;padding:2px 7px;background:hsla(0,0%,50%,.15);border-radius:10px;color:var(--text-secondary)}.cat-actions{display:none;align-items:center;gap:2px}.category-item-row:hover .cat-actions{display:flex}.content-area{flex:1 1;padding:28px 32px;overflow-y:auto;display:flex;flex-direction:column;gap:24px}.content-header{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap}.category-info-badge h2{font-size:1.6rem;font-weight:700;letter-spacing:-.02em}.category-info-badge p{font-size:.9rem;color:var(--text-secondary);margin-top:4px}.header-buttons-row{display:flex;align-items:center;gap:10px}.cards-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));grid-gap:20px;gap:20px}.apple-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:20px;transition:border-color .15s ease;display:flex;flex-direction:column;justify-content:space-between;gap:16px;position:relative;overflow:hidden}.apple-card:hover{border-color:var(--accent)}.flashcard-item-card{min-height:190px}.card-top-info{display:flex;align-items:center;justify-content:space-between}.card-tag{font-size:.72rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em;padding:3px 8px;background:var(--accent-light);color:var(--accent);border-radius:6px}.card-preview-body{flex:1 1;font-size:.95rem;line-height:1.5;color:var(--text-primary);display:-webkit-box;-webkit-line-clamp:4;-webkit-box-orient:vertical;overflow:hidden}.card-footer-actions{display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--border-color);padding-top:12px;margin-top:auto}.btn-apple{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:10px 18px;border-radius:var(--radius-sm);font-family:var(--font-sans);font-size:.88rem;font-weight:600;cursor:pointer;border:none;transition:background-color .15s ease;-webkit-user-select:none;-moz-user-select:none;user-select:none}.btn-primary{background:var(--accent);color:var(--accent-text)}.btn-primary:hover{background:var(--accent-hover)}.btn-secondary{background:var(--bg-input);color:var(--text-primary);border:1px solid var(--border-color)}.btn-secondary:hover{background:hsla(0,0%,50%,.2)}.btn-sm{padding:6px 12px;font-size:.8rem;border-radius:8px}.btn-icon{width:38px;height:38px;padding:0;border-radius:10px}.btn-icon-subtle{background:transparent;border:none;color:var(--text-secondary);padding:4px;border-radius:6px;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;transition:all .12s ease}.btn-icon-subtle:hover{background:hsla(0,0%,50%,.15);color:var(--text-primary)}.btn-icon-subtle.danger:hover{background:var(--danger-light);color:var(--danger)}.modal-backdrop{position:fixed;inset:0;background:rgba(0,0,0,.6);display:flex;align-items:center;justify-content:center;z-index:1000;padding:20px;animation:fadeIn .15s ease-out}.modal-content{background:var(--bg-modal);border:1px solid var(--border-color);width:100%;max-height:90vh;display:flex;flex-direction:column}.modal-md{max-width:520px}.modal-lg{max-width:820px}.modal-header{padding:18px 24px;border-bottom:1px solid var(--border-color);display:flex;align-items:center;justify-content:space-between}.modal-title-group h2{font-size:1.25rem;font-weight:700}.modal-title-group .subtitle{font-size:.8rem;color:var(--text-secondary)}.modal-body{padding:24px;overflow-y:auto;display:flex;flex-direction:column;gap:20px}.modal-footer{padding:16px 24px;border-top:1px solid var(--border-color);display:flex;align-items:center;justify-content:flex-end;gap:12px}.form-group{display:flex;flex-direction:column;gap:6px}.form-label{font-size:.85rem;font-weight:600;color:var(--text-secondary);display:flex;align-items:center;gap:6px}.apple-input{width:100%;padding:12px 14px;background:var(--bg-input);border:1px solid var(--border-color);border-radius:var(--radius-sm);color:var(--text-primary);font-family:var(--font-sans);font-size:.92rem;outline:none;transition:border-color .15s ease}.apple-input:focus{border-color:var(--accent)}.apple-textarea{resize:vertical;min-height:100px;font-family:var(--font-sans)}.type-selector-pills{display:flex;gap:6px;margin-bottom:6px}.pill-btn{display:inline-flex;align-items:center;gap:4px;padding:4px 10px;border-radius:14px;font-size:.75rem;font-weight:500;background:var(--bg-input);border:1px solid var(--border-color);color:var(--text-secondary);cursor:pointer;transition:all .12s ease}.pill-btn.active{background:var(--accent-light);color:var(--accent);border-color:var(--accent);font-weight:600}.study-backdrop{background:rgba(0,0,0,.8)}.study-modal-card{max-width:720px;min-height:560px}.study-header{display:flex;align-items:center;justify-content:space-between;padding:16px 24px;border-bottom:1px solid var(--border-color)}.study-badge{font-size:.75rem;font-weight:600;text-transform:uppercase;color:var(--accent)}.study-progress-wrapper{padding:12px 24px 0}.progress-text-row{display:flex;justify-content:space-between;font-size:.8rem;color:var(--text-secondary);margin-bottom:6px}.apple-progress-bar{height:6px;background:var(--bg-input);border-radius:3px;overflow:hidden}.progress-fill{height:100%;background:var(--accent);transition:width .3s ease}.flashcard-3d-scene{perspective:1200px;width:100%;height:320px;margin:16px 0;padding:0 24px}.flashcard-3d-card{width:100%;height:100%;position:relative;transform-style:preserve-3d;transition:transform .6s cubic-bezier(.4,.2,.2,1);cursor:pointer}.flashcard-3d-card.flipped{transform:rotateY(180deg)}.card-face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;border-radius:var(--radius-md);padding:24px;border:1px solid var(--border-color);display:flex;flex-direction:column;justify-content:space-between}.card-back,.card-face,.card-front{background:var(--bg-card)}.card-back{transform:rotateY(180deg);border-color:var(--accent)}.face-tag{font-size:.75rem;font-weight:600;text-transform:uppercase;color:var(--text-tertiary);letter-spacing:.05em}.card-content-scroll{flex:1 1;overflow-y:auto;text-align:center;font-size:1.2rem;padding:12px 0}.card-content-scroll,.flip-prompt{display:flex;align-items:center;justify-content:center}.flip-prompt{gap:6px;font-size:.78rem;color:var(--text-tertiary)}.study-action-bar{justify-content:space-between;padding:16px 24px;gap:12px;border-top:1px solid var(--border-color)}.btn-rate,.study-action-bar{display:flex;align-items:center}.btn-rate{flex:1 1;justify-content:center;gap:8px;padding:12px;border-radius:var(--radius-sm);font-weight:600;font-size:.9rem;cursor:pointer;border:none;transition:background-color .15s ease}.btn-review{background:var(--danger-light);color:var(--danger)}.btn-review:hover{background:rgba(255,59,48,.22)}.btn-mastered{background:rgba(52,199,89,.15);color:var(--success)}.btn-mastered:hover{background:rgba(52,199,89,.25)}.completion-screen{flex-direction:column;padding:40px 24px;text-align:center;gap:16px}.completion-screen,.trophy-badge{display:flex;align-items:center;justify-content:center}.trophy-badge{width:80px;height:80px;border-radius:50%;background:var(--accent-light);color:var(--accent);margin-bottom:8px}.completion-stats-grid{display:flex;gap:20px;margin:16px 0}.stat-card{padding:16px 28px;border-radius:var(--radius-sm);display:flex;flex-direction:column;align-items:center}.stat-card.mastered{background:rgba(52,199,89,.15);color:var(--success)}.stat-card.review{background:var(--danger-light);color:var(--danger)}.stat-value{font-size:1.8rem;font-weight:700}.stat-label{font-size:.8rem}.segmented-control{display:flex;background:var(--bg-input);padding:3px;border-radius:10px;border:1px solid var(--border-color)}.segmented-item{padding:5px 12px;border-radius:7px;border:none;background:transparent;font-size:.8rem;font-weight:500;color:var(--text-secondary);cursor:pointer;display:flex;align-items:center;gap:6px;transition:all .12s ease}.segmented-item.active{background:var(--bg-card);color:var(--text-primary);font-weight:600}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@media (max-width:768px){.main-layout{flex-direction:column}.category-sidebar{width:100%;border-right:none;border-bottom:1px solid var(--border-color);max-height:240px}.content-area{padding:16px}.cards-grid{grid-template-columns:1fr}.desktop-only{display:none}.flashcard-3d-scene{height:280px}.study-action-bar{flex-direction:column}.btn-rate{width:100%}}