:root{--font-sans:"Inter", system-ui, -apple-system, sans-serif;--bg-primary:#0f111a;--bg-secondary:#ffffff08;--glass-bg:#14162399;--glass-border:#ffffff14;--glass-highlight:#ffffff1f;--text-primary:#f8fafc;--text-secondary:#94a3b8;--accent-primary:#8b5cf6;--accent-secondary:#ec4899;--accent-gradient:linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);--success:#10b981;--warning:#f59e0b;--glow-shadow:0 0 20px #8b5cf64d}*{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-sans);background-color:var(--bg-primary);color:var(--text-primary);background-image:radial-gradient(circle at 15%,#8b5cf626 0%,#0000 50%),radial-gradient(circle at 85% 30%,#ec489926 0%,#0000 50%);flex-direction:column;min-height:100vh;line-height:1.5;display:flex}.glass-panel{background:var(--glass-bg);-webkit-backdrop-filter:blur(12px);border:1px solid var(--glass-border);border-radius:16px;padding:24px;box-shadow:0 8px 32px #0000004d}.glass-header{-webkit-backdrop-filter:blur(20px);border-bottom:1px solid var(--glass-border);z-index:50;background:#0f111acc;justify-content:space-between;align-items:center;padding:16px 32px;display:flex;position:sticky;top:0}.app-container{height:100vh;display:flex;overflow:hidden}.sidebar{border-right:1px solid var(--glass-border);z-index:40;background:#0f111af2;flex-direction:column;width:280px;height:100%;padding:24px 16px;display:flex}.main-content{flex-direction:column;flex:1;height:100%;display:flex;position:relative;overflow-y:auto}.content-wrapper{width:100%;max-width:1200px;margin:0 auto;padding:32px}.text-gradient{background:var(--accent-gradient);-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text}.btn{cursor:pointer;border:none;border-radius:10px;justify-content:center;align-items:center;gap:8px;padding:10px 20px;font-family:inherit;font-size:14px;font-weight:600;transition:all .3s cubic-bezier(.4,0,.2,1);display:inline-flex}.btn-primary{background:var(--accent-gradient);color:#fff;box-shadow:var(--glow-shadow)}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 0 30px #ec489980}.btn-glass{background:var(--glass-highlight);border:1px solid var(--glass-border);color:var(--text-primary);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px)}.btn-glass:hover{background:#fff3;transform:translateY(-1px)}.nav-item{color:var(--text-secondary);cursor:pointer;border-radius:10px;align-items:center;gap:12px;margin-bottom:4px;padding:12px 16px;font-weight:500;text-decoration:none;transition:all .2s;display:flex}.nav-item:hover{color:var(--text-primary);background:var(--glass-highlight)}.nav-item.active{color:#fff;background:var(--accent-gradient);box-shadow:var(--glow-shadow)}.chat-container{flex-direction:column;gap:24px;display:flex}.message{gap:16px;max-width:80%;display:flex}.message.ai{align-self:flex-start}.message.user{flex-direction:row-reverse;align-self:flex-end}.message-bubble{border-radius:16px;padding:16px 20px;font-size:15px;line-height:1.6}.message.ai .message-bubble{background:var(--glass-bg);border:1px solid var(--glass-border);border-bottom-left-radius:4px}.message.user .message-bubble{background:var(--accent-primary);color:#fff;border-bottom-right-radius:4px;box-shadow:0 4px 15px #8b5cf666}.input-area{background:linear-gradient(to top, var(--bg-primary) 80%, transparent);padding:24px;position:sticky;bottom:0}.input-box{background:var(--glass-bg);border:1px solid var(--glass-border);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);border-radius:16px;align-items:center;gap:12px;padding:8px 16px;transition:border-color .3s;display:flex}.input-box:focus-within{border-color:var(--accent-primary);box-shadow:0 0 0 2px #8b5cf633}.input-field{color:#fff;background:0 0;border:none;outline:none;flex:1;padding:12px 0;font-size:15px}.input-field::placeholder{color:var(--text-secondary)}.lesson-progress{border-top:1px solid var(--glass-border);align-items:center;gap:12px;margin-top:32px;padding-top:24px;display:flex}.progress-bar-bg{background:var(--glass-border);border-radius:3px;flex:1;height:6px;overflow:hidden}.progress-bar-fill{background:var(--accent-gradient);border-radius:3px;height:100%;transition:width .5s}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:0 0}::-webkit-scrollbar-thumb{background:var(--glass-border);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--glass-highlight)}