@import "https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=Outfit:wght@400;600;700&display=swap";:root{--bg-color:#0b0c10;--surface-color:#1f2833;--surface-color-light:#2c3947;--text-primary:#fff;--text-secondary:#8b9bb4;--accent-color:#66fcf1;--accent-glow:#66fcf166;--border-color:#ffffff1a;--card-bg:#1f283399;--card-shadow:0 8px 32px 0 #0000005e;--success:#4ade80;--warning:#fbbf24}*{box-sizing:border-box;margin:0;padding:0;font-family:Inter,sans-serif}body{background-color:var(--bg-color);color:var(--text-primary);background-image:radial-gradient(circle at 15%,#66fcf10d,#0000 25%),radial-gradient(circle at 85% 30%,#1f283380,#0000 25%);flex-direction:column;min-height:100vh;display:flex;overflow-x:hidden}h1,h2,h3,h4,h5,h6{letter-spacing:-.02em;font-family:Outfit,sans-serif}button{cursor:pointer;background:0 0;border:none;font-family:Inter,sans-serif;transition:all .2s}.app-container{flex-direction:column;width:100%;max-width:1200px;min-height:100vh;margin:0 auto;padding:2rem;display:flex}.header{justify-content:space-between;align-items:center;margin-bottom:2rem;display:flex}.header h1{background:linear-gradient(90deg, #fff, var(--text-secondary));-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text;font-size:2rem;font-weight:700}.controls{align-items:center;gap:1rem;display:flex}.toggle-container{color:var(--text-secondary);align-items:center;gap:.5rem;font-size:.9rem;display:flex}.toggle-switch{background-color:var(--surface-color);cursor:pointer;border:1px solid var(--border-color);border-radius:12px;width:44px;height:24px;transition:background-color .3s;position:relative}.toggle-switch.active{background-color:var(--accent-color)}.toggle-knob{background-color:#fff;border-radius:50%;width:18px;height:18px;transition:transform .3s cubic-bezier(.4,0,.2,1);position:absolute;top:2px;left:2px}.toggle-switch.active .toggle-knob{transform:translate(20px)}.card-container{perspective:1000px;flex-direction:column;flex:1;justify-content:center;align-items:center;width:100%;margin:2rem 0;display:flex}.flashcard{aspect-ratio:3/2;width:100%;max-width:600px;transform-style:preserve-3d;cursor:pointer;position:relative}.card-face{backface-visibility:hidden;text-align:center;background:var(--card-bg);-webkit-backdrop-filter:blur(10px);border:1px solid var(--border-color);width:100%;height:100%;box-shadow:var(--card-shadow);border-radius:20px;flex-direction:column;justify-content:center;align-items:center;padding:2rem;display:flex;position:absolute}.card-front{background:linear-gradient(145deg, var(--surface-color), #1a222b)}.card-back{background:linear-gradient(145deg, #151b22, var(--surface-color));transform:rotateX(180deg)}.card-label{text-transform:uppercase;letter-spacing:.1em;color:var(--accent-color);opacity:.8;font-size:.8rem;font-weight:600;position:absolute;top:1.5rem;left:1.5rem}.card-chapter{color:var(--text-secondary);background:#ffffff0d;border-radius:12px;padding:.2rem .6rem;font-size:.8rem;font-weight:500;position:absolute;top:1.5rem;right:1.5rem}.card-content{font-size:1.5rem;font-weight:400;line-height:1.4}.card-answer{color:#e0e6ed;font-size:1.25rem}.card-answer ul{text-align:left;margin-top:1rem;padding-left:1.5rem}.card-answer li{margin-bottom:.5rem}.nav-controls{justify-content:center;align-items:center;gap:2rem;margin-top:2rem;display:flex}.nav-btn{background:var(--surface-color);width:50px;height:50px;color:var(--text-primary);border:1px solid var(--border-color);border-radius:50%;justify-content:center;align-items:center;display:flex;box-shadow:0 4px 12px #0003}.nav-btn:hover:not(:disabled){background:var(--surface-color-light);color:var(--accent-color);transform:translateY(-2px);box-shadow:0 6px 16px #0000004d}.nav-btn:active:not(:disabled){transform:translateY(0)}.nav-btn:disabled{opacity:.5;cursor:not-allowed}.progress-container{flex-direction:column;align-items:center;gap:.5rem;width:100%;max-width:600px;margin:1.5rem auto 0;display:flex}.progress-bar{background:#ffffff1a;border-radius:2px;width:100%;height:4px;overflow:hidden}.progress-fill{background:var(--accent-color);height:100%;box-shadow:0 0 10px var(--accent-glow);border-radius:2px;transition:width .3s}.progress-text{color:var(--text-secondary);font-size:.85rem;font-weight:500}.chapter-selector{flex-wrap:wrap;justify-content:center;gap:.5rem;margin-bottom:1rem;padding:.5rem 0;display:flex}.chapter-pill{color:var(--text-secondary);white-space:nowrap;background:#ffffff0d;border:1px solid #0000;border-radius:20px;padding:.4rem 1rem;font-size:.85rem;font-weight:500}.chapter-pill:hover{background:#ffffff1a}.chapter-pill.active{color:var(--accent-color);background:#66fcf11a;border-color:#66fcf14d}.side-by-side-cards{justify-content:center;align-items:stretch;gap:2rem;width:100%;display:flex}.side-by-side-cards .flashcard{aspect-ratio:auto;flex:1;max-width:600px;min-height:400px}.flashcard.static-card{transform-style:flat;cursor:default}@media (width<=900px){.side-by-side-cards{flex-direction:column;align-items:center}}@media (width<=600px){.app-container{padding:1rem}.card-content{font-size:1.2rem}.card-answer{font-size:1.1rem}.flashcard{aspect-ratio:4/5}}.footer{text-align:center;color:var(--text-secondary);margin-top:auto;padding:3rem 0 1rem;font-size:.9rem}.footer p{margin:0}.footer a{color:var(--accent-color);font-weight:500;text-decoration:none;transition:all .2s}.footer a:hover{color:#fff;text-shadow:0 0 10px var(--accent-glow)}