:root{--bg-color:#0f172a;--glass-bg:#ffffff08;--glass-border:#ffffff1a;--primary-glow:#38bdf8;--secondary-glow:#818cf8;--accent-glow:#f472b6;--text-main:#f8fafc;--text-muted:#94a3b8;--card-width:450px;--card-height:300px;--transition-speed:.6s}*{box-sizing:border-box;margin:0;padding:0}body{background-color:var(--bg-color);color:var(--text-main);background-image:radial-gradient(at 0 0,#100f15 0,#0000 50%),radial-gradient(at 50% 0,#2f3e6a 0,#0000 50%),radial-gradient(at 100% 0,#722741 0,#0000 50%);justify-content:center;align-items:center;min-height:100vh;font-family:Inter,sans-serif;display:flex;overflow-x:hidden}#app{flex-direction:column;gap:2rem;width:100%;max-width:800px;padding:2rem;display:flex}header{justify-content:space-between;align-items:center;display:flex}.logo{background:linear-gradient(to right, var(--primary-glow), var(--secondary-glow));-webkit-text-fill-color:transparent;-webkit-background-clip:text;font-family:Outfit,sans-serif;font-size:1.5rem;font-weight:800}.header-actions{gap:1rem;display:flex}.upload-btn{background:var(--glass-bg);border:1px solid var(--glass-border);cursor:pointer;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-radius:12px;padding:1rem;font-size:.9rem;transition:all .3s}.upload-btn:hover{border-color:var(--primary-glow);background:#ffffff1a}.icon-btn{background:var(--glass-bg);border:1px solid var(--glass-border);color:var(--text-main);cursor:pointer;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-radius:12px;padding:.7rem;transition:all .3s}.icon-btn:hover{color:var(--primary-glow);background:#ffffff1a;transform:rotate(180deg)}main{flex-direction:column;align-items:center;gap:1.5rem;display:flex}.progress-bar{background:var(--glass-bg);border-radius:10px;width:100%;height:6px;overflow:hidden}.progress-fill{background:linear-gradient(to right, var(--primary-glow), var(--secondary-glow));width:0%;height:100%;box-shadow:0 0 10px var(--primary-glow);transition:width .4s}.stats{color:var(--text-muted);font-size:.9rem}.range-controls{background:var(--glass-bg);border:1px solid var(--glass-border);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-radius:16px;align-items:flex-end;gap:1.5rem;padding:1rem 1.5rem;display:flex}.sheet-selector{background:var(--glass-bg);border:1px solid var(--glass-border);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-radius:16px;width:50%;padding:1rem 1.5rem}.input-group{flex-direction:column;gap:.5rem;display:flex}.input-group.full-width{width:100%}.input-group label{text-transform:uppercase;color:var(--text-muted);letter-spacing:.05em;font-size:.75rem;font-weight:600}.input-group input,.input-group select{border:1px solid var(--glass-border);color:var(--text-main);background:#ffffff0d;border-radius:8px;outline:none;padding:.5rem;transition:all .3s}.input-group input{width:80px}.input-group select{appearance:none;cursor:pointer;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' fill='none' stroke='%2394a3b8' viewBox='0 0 24 24'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");background-position:right .7rem center;background-repeat:no-repeat;width:100%;padding-right:2.5rem}.input-group select option{background-color:var(--bg-color);color:var(--text-main)}.input-group input:focus,.input-group select:focus{border-color:var(--primary-glow)}.input-group select:hover{border-color:var(--primary-glow);background-color:#ffffff1a}.range-btn{background:var(--glass-bg);border:1px solid var(--glass-border);color:var(--text-main);cursor:pointer;border-radius:8px;height:38px;padding:.5rem 1rem;font-size:.85rem;font-weight:600;transition:all .3s}.range-btn:hover{border-color:var(--primary-glow);color:var(--primary-glow);background:#ffffff1a}.card-container{perspective:1000px;width:var(--card-width);height:var(--card-height);cursor:pointer}.card{width:100%;height:100%;transition:transform var(--transition-speed);transform-style:preserve-3d;position:relative}.card.is-flipped{transform:rotateY(180deg)}.card-face{backface-visibility:hidden;background:var(--glass-bg);border:1px solid var(--glass-border);-webkit-backdrop-filter:blur(20px);backdrop-filter:blur(20px);text-align:center;border-radius:24px;flex-direction:column;justify-content:center;align-items:center;width:100%;height:100%;padding:2rem;display:flex;position:absolute;box-shadow:0 25px 50px -12px #00000080}.card-front h1{letter-spacing:-.02em;margin-bottom:1rem;font-family:Outfit,sans-serif;font-size:3.5rem;font-weight:600}.card-back{text-align:left;justify-content:flex-start;align-items:flex-start;overflow-y:auto;transform:rotateY(180deg)}.label{text-transform:uppercase;letter-spacing:.1em;color:var(--primary-glow);margin-bottom:.5rem;font-size:.75rem;font-weight:700}.content-group{margin-bottom:1.5rem}#meaning-display{font-size:1.1rem;line-height:1.6}.example-text,.synonyms-text{color:var(--text-muted);border-left:2px solid var(--secondary-glow);padding-left:1rem;font-size:.95rem;font-style:italic}.bookmark-btn{background:var(--glass-bg);border:1px solid var(--glass-border);color:var(--text-muted);cursor:pointer;z-index:10;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-radius:20px;justify-content:center;align-items:center;padding:.6rem;transition:all .3s cubic-bezier(.4,0,.2,1);display:flex;position:absolute;top:.5rem;right:.5rem}.bookmark-btn:hover{color:#fbbf24;background:#fbbf241a;border-color:#fbbf24}.bookmark-btn.active{color:#fbbf24;background:#fbbf2426;border-color:#fbbf24;box-shadow:0 0 20px #fbbf2433}.bookmark-btn.active svg{fill:currentColor}.hint{color:var(--text-muted);opacity:.6;margin-top:auto;font-size:.8rem}.controls{align-items:center;gap:2rem;display:flex}.nav-btn{border:1px solid var(--glass-border);color:var(--text-main);cursor:pointer;background:0 0;border-radius:50%;padding:.8rem;transition:all .3s}.nav-btn:hover{background:var(--glass-bg);color:var(--primary-glow);transform:scale(1.1)}.action-btn{background:linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));color:#fff;cursor:pointer;border:none;border-radius:16px;padding:1rem 2.5rem;font-size:1rem;font-weight:700;transition:all .3s;box-shadow:0 10px 15px -3px #38bdf84d}.action-btn:hover{transform:translateY(-2px);box-shadow:0 20px 25px -5px #38bdf866}.card.fading{opacity:0;transform:scale(.95)}.card-face{transition:opacity .3s,transform .3s}footer{text-align:center;color:var(--text-muted);font-size:.85rem}@media (width<=640px){:root{--card-width:100%;--card-height:350px}.card-front h1{font-size:2.5rem}}