:root{color-scheme:dark;font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.5;--bg: #0f0f13;--surface: #1a1a24;--border: rgba(255, 255, 255, .08);--accent: #6c63ff;--accent-hover: #5a52e0;--danger: #e05555;--text: #eaeaef;--muted: rgba(255, 255, 255, .5)}*{box-sizing:border-box;margin:0}html,body,#root{min-height:100vh;background:var(--bg);color:var(--text)}.app{max-width:520px;margin:0 auto;padding:2rem 1.25rem 4rem}.app-title{font-size:1.6rem;font-weight:700;letter-spacing:-.03em;text-align:center;margin-bottom:1.5rem}.tabs{display:flex;gap:.5rem;margin-bottom:1.5rem}.tab-btn{flex:1;padding:.6rem .75rem;border:1px solid var(--border);border-radius:.5rem;background:transparent;color:var(--muted);font-size:.85rem;font-weight:500;cursor:pointer;transition:all .15s}.tab-btn:hover{color:var(--text);border-color:#ffffff26}.tab-btn.active{background:var(--accent);border-color:var(--accent);color:#fff}.section{display:flex;flex-direction:column;gap:1rem}.add-form{display:flex;gap:.5rem}.add-form input{flex:1;padding:.55rem .75rem;border:1px solid var(--border);border-radius:.5rem;background:var(--surface);color:var(--text);font-size:.9rem;outline:none}.add-form input:focus{border-color:var(--accent)}.btn{padding:.5rem 1rem;border:1px solid var(--border);border-radius:.5rem;background:var(--surface);color:var(--text);font-size:.85rem;cursor:pointer;transition:all .15s}.btn:hover{border-color:#fff3}.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}.btn.primary:hover{background:var(--accent-hover)}.btn.danger{color:var(--danger);border-color:var(--danger)}.btn.danger:hover{background:var(--danger);color:#fff}.btn-sm{background:none;border:none;color:var(--muted);font-size:1.2rem;cursor:pointer;padding:0 .3rem;line-height:1}.btn-sm:hover{color:var(--danger)}.flashcard-area{display:flex;flex-direction:column;align-items:center;gap:.75rem}.flashcard{width:100%;max-width:360px;height:200px;perspective:800px;cursor:pointer}.flashcard-inner{width:100%;height:100%;position:relative;transition:transform .5s;transform-style:preserve-3d}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{position:absolute;top:0;right:0;bottom:0;left:0;display:grid;place-items:center;padding:1.5rem;border:1px solid var(--border);border-radius:.75rem;background:var(--surface);font-size:1.1rem;backface-visibility:hidden;text-align:center;word-break:break-word}.flashcard-back{transform:rotateY(180deg);background:linear-gradient(135deg,#1e1e2e,#2a2a3e);border-color:var(--accent)}.hint{font-size:.75rem;color:var(--muted)}.nav-row{display:flex;align-items:center;gap:.75rem}.counter{font-size:.85rem;color:var(--muted);min-width:5rem;text-align:center}.empty{color:var(--muted);text-align:center;padding:2rem 0;font-size:.9rem}.timer-section{align-items:center}.timer-label{font-size:.85rem;text-transform:uppercase;letter-spacing:.15em;color:var(--accent);font-weight:600}.timer-display{font-size:5rem;font-weight:200;font-variant-numeric:tabular-nums;letter-spacing:.04em;line-height:1}.task-list{list-style:none;display:flex;flex-direction:column;gap:.4rem}.task-item{display:flex;align-items:center;justify-content:space-between;padding:.55rem .75rem;border:1px solid var(--border);border-radius:.5rem;background:var(--surface);transition:opacity .2s}.task-item.done{opacity:.45}.task-item.done span{text-decoration:line-through}.task-item label{display:flex;align-items:center;gap:.6rem;cursor:pointer;flex:1;font-size:.9rem}.task-item input[type=checkbox]{accent-color:var(--accent);width:1rem;height:1rem}