*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}:root{--bg: #eef0f4;--surface: #ffffff;--border: #e2e4e9;--accent: #6366f1;--accent-hover: #4f46e5;--accent-tint: rgba(99, 102, 241, .08);--text: #0f1117;--muted: #6b7280;--muted-hover: #4b5563;--radius: 10px;--radius-lg: 16px;--score-good: #16a34a;--score-ok: #d97706;--score-bad: #dc2626}html,body{min-height:100vh;background:var(--bg);color:var(--text);font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:16px;line-height:1.5;-webkit-font-smoothing:antialiased;transition:background .2s,color .2s}a{color:inherit;text-decoration:none}button{font-family:inherit;cursor:pointer}.mono{font-family:JetBrains Mono,Fira Code,Courier New,monospace}.nav-bar{border-bottom:1px solid var(--border);background:var(--bg);position:sticky;top:0;z-index:100;transition:background .2s,border-color .2s}.nav{display:flex;align-items:center;justify-content:space-between;max-width:960px;margin:0 auto;padding:0 48px;height:56px}.nav-logo{display:flex;align-items:center;gap:9px;font-size:16px;font-weight:600;letter-spacing:-.01em;color:var(--text)}.nav-logo-box{display:inline-flex;align-items:center;justify-content:center;width:28px;height:28px;background:var(--text);color:#fff;font-size:11px;font-weight:700;border-radius:6px;font-family:JetBrains Mono,monospace;flex-shrink:0;letter-spacing:-.02em}.nav-links{display:flex;align-items:center;gap:32px}.nav-link{font-size:14px;color:var(--muted);transition:color .15s}.nav-link:hover{color:var(--text)}.streak-pill{display:inline-flex;align-items:center;gap:6px;padding:5px 12px;border-radius:999px;background:#fff7ed;color:#c2410c;border:1px solid #fed7aa;font-size:13px;font-weight:500;white-space:nowrap}.btn-primary{padding:10px 20px;background:var(--text);color:#fff;border:none;border-radius:var(--radius);font-size:14px;font-weight:500;cursor:pointer;transition:background .12s;white-space:nowrap;display:inline-flex;align-items:center}.btn-primary.large{padding:13px 28px;font-size:15px}.btn-primary:hover{background:#1f2937}.btn-primary:disabled{background:var(--border);color:var(--muted);cursor:not-allowed}.btn-ghost{padding:13px 28px;background:var(--surface);color:var(--text);border:1px solid var(--border);border-radius:var(--radius);font-size:15px;font-weight:500;cursor:pointer;transition:border-color .15s,color .15s;display:inline-flex;align-items:center}.btn-ghost:hover{border-color:var(--accent);color:var(--accent)}.btn-ghost-sm{padding:10px 18px;background:var(--surface);color:var(--muted);border:1px solid var(--border);border-radius:var(--radius);font-size:14px;cursor:pointer;transition:border-color .15s,color .15s;display:inline-flex;align-items:center}.btn-ghost-sm:hover{border-color:var(--accent);color:var(--accent)}.btn-signin{padding:7px 16px;background:var(--surface);color:var(--text);border:1px solid var(--border);border-radius:var(--radius);font-size:13px;font-weight:500;cursor:pointer;transition:background .12s}.btn-signin:hover{background:var(--accent-tint)}.auth-menu{position:relative}.auth-dropdown{position:absolute;top:calc(100% + 8px);right:0;min-width:200px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:0 12px 32px #00000047;padding:6px;z-index:100;animation:auth-dropdown-in .15s ease}@keyframes auth-dropdown-in{0%{opacity:0;transform:translateY(-4px) scale(.98)}to{opacity:1;transform:translateY(0) scale(1)}}.auth-dropdown-label{padding:8px 10px;font-size:12px;font-weight:500;letter-spacing:.02em;text-transform:uppercase;color:var(--muted);border-bottom:1px solid var(--border);margin-bottom:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.auth-dropdown-item{display:block;width:100%;text-align:left;padding:8px 10px;background:transparent;border:none;border-radius:var(--radius);color:var(--text);font-size:14px;text-decoration:none;cursor:pointer;white-space:nowrap;transition:background .12s,transform .08s}.auth-dropdown-item:hover{background:var(--accent-tint)}.auth-dropdown-item:active{transform:scale(.98)}.user-avatar-btn{background:none;border:none;padding:0;cursor:pointer;display:flex;align-items:center}.user-avatar{width:32px;height:32px;border-radius:50%;object-fit:cover;border:1px solid var(--border)}.user-avatar-fallback{display:flex;align-items:center;justify-content:center;background:var(--accent);color:var(--bg);font-size:14px;font-weight:600}.filter-pills{display:flex;gap:8px;flex-wrap:wrap;padding:24px 0}.filter-pill{padding:6px 16px;border-radius:999px;border:1px solid var(--border);background:var(--surface);color:var(--muted);font-size:14px;cursor:pointer;transition:all .15s}.filter-pill:hover{color:var(--text);border-color:var(--accent)}.filter-pill.active{background:var(--accent);color:#fff;border-color:var(--accent)}.challenge-list{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden}.challenge-row{display:flex;align-items:center;gap:16px;padding:18px 24px;border-bottom:1px solid var(--border);cursor:pointer;transition:background .12s}.challenge-row:last-child{border-bottom:none}.challenge-row:hover{background:var(--accent-tint)}.cat-tag{display:inline-flex;align-items:center;padding:3px 10px;border-radius:var(--radius);font-size:12px;font-weight:500;font-family:JetBrains Mono,monospace;background:var(--accent-tint);color:var(--muted-hover);border:1px solid var(--border);white-space:nowrap;flex-shrink:0}.profile-header{display:flex;align-items:center;gap:16px;padding-top:40px}.profile-avatar{width:64px;height:64px;border-radius:var(--radius);object-fit:cover;border:1px solid var(--border)}.profile-avatar-fallback{display:flex;align-items:center;justify-content:center;background:var(--accent-tint);color:var(--accent);font-size:24px;font-weight:600}.pill-muted{display:inline-flex;align-items:center;padding:6px 14px;border-radius:999px;background:var(--border);color:var(--muted);font-family:JetBrains Mono,monospace;font-size:13px;font-weight:500;white-space:nowrap}.stats-card{display:flex;border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden}.stats-card-cell{flex:1;padding:24px 28px;border-right:1px solid var(--border)}.stats-card-cell:last-child{border-right:none}.track-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.track-card-icon{color:var(--muted);margin-bottom:12px}.track-card{display:block;width:100%;font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px;cursor:pointer;text-align:left;transition:transform .12s,border-color .12s,background .12s}.track-card:hover{transform:translateY(-2px);background:var(--accent-tint)}.track-card-header{display:flex;align-items:flex-start;justify-content:space-between;gap:8px;margin-bottom:12px}.track-card-name{font-size:16px;font-weight:600;margin-bottom:4px}.track-card-desc{font-size:13px;color:var(--muted);line-height:1.5;margin-bottom:16px}.question-tags{display:flex;align-items:center;gap:6px;margin-bottom:20px;flex-wrap:wrap}.question-tag{display:inline-flex;align-items:center;padding:3px 10px;border-radius:999px;font-size:12px;background:var(--bg);border:1px solid var(--border);color:var(--muted);white-space:nowrap}.icon-btn{background:none;border:none;cursor:pointer;padding:5px;display:flex;align-items:center;justify-content:center;border-radius:6px;color:var(--muted);transition:background .1s,color .1s}.icon-btn:hover{background:var(--border);color:var(--text)}.icon-btn.active{color:var(--text)}.session-actions-bar{display:flex;justify-content:space-between;align-items:center;padding:18px 0 32px}.session-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden;margin-bottom:32px}.result-pill{display:inline-flex;align-items:center;padding:5px 14px;border-radius:999px;font-size:13px;font-weight:600}.result-pill.correct{background:#16a34a1a;color:var(--score-good)}.result-pill.incorrect{background:#dc26261a;color:var(--score-bad)}.stat-summary{display:flex;gap:40px;flex-wrap:wrap;padding:18px 24px;margin-top:16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg)}.stat-summary-item{display:flex;flex-direction:column;gap:4px}.stat-summary-label{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.04em}.stat-summary-value{font-size:18px;font-weight:600;color:var(--text)}.session-card-body{padding:24px}.session-card-footer{display:flex;justify-content:space-between;align-items:center;padding:16px 24px;border-top:1px solid var(--border)}.session-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-lg);padding:24px 28px}.session-stats>div{padding-left:24px;border-left:1px solid var(--border)}.session-stats>div:first-child{padding-left:0;border-left:none}.session-stat-value{font-size:28px;font-weight:700;color:var(--text);margin-bottom:4px}.session-stat-label{font-size:13px;color:var(--muted)}@media(max-width:640px){.session-stats{grid-template-columns:repeat(2,1fr);gap:24px 16px}.session-stats>div:nth-child(odd){padding-left:0;border-left:none}}.step-indicator{display:flex;align-items:center;gap:10px;margin-bottom:32px}.step-label{font-family:JetBrains Mono,monospace;font-size:13px;color:var(--muted)}.step-label.active{color:var(--text);font-weight:600}.step-arrow{color:var(--border);font-size:13px;line-height:1}.textarea-input{width:100%;padding:12px 14px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);color:var(--text);font-size:14px;line-height:1.65;resize:vertical;outline:none;font-family:inherit;transition:border-color .15s}.textarea-input:focus{border-color:var(--accent)}.textarea-input::placeholder{color:var(--muted)}.term-input{width:100%;padding:12px 16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);color:var(--text);font-size:17px;font-family:inherit;outline:none;transition:border-color .15s}.term-input:focus{border-color:var(--accent)}.term-input::placeholder{color:var(--muted);font-size:14px}.term-input:disabled{opacity:.6}.feedback-item{display:flex;gap:10px;align-items:flex-start;padding:10px 14px;border-radius:var(--radius);border:1px solid}.feedback-hit{background:#4ade800f;border-color:#4ade802e}.feedback-miss{background:#f871710f;border-color:#f871712e}.feedback-icon{font-size:13px;margin-top:2px;flex-shrink:0;font-family:JetBrains Mono,monospace;font-weight:600}.empty-state{padding:56px;text-align:center;color:var(--muted)}.progress-bar{height:4px;background:var(--border);border-radius:999px;overflow:hidden}.progress-bar-fill{height:100%;background:var(--accent)}input[type=range]{width:100%;accent-color:var(--accent);cursor:pointer;height:4px}.footer{border-top:1px solid var(--border);margin-top:24px}.footer .content-wide{padding-top:0}.footer-inner{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:24px;padding:24px 0}.content-wide{max-width:960px;margin:0 auto;padding:48px 48px 32px}.content-wide.challenges{padding-top:0;padding-bottom:80px}.content-narrow{max-width:780px;margin:0 auto;padding:48px 32px 96px}@media(max-width:640px){.nav{padding:0 20px}.nav-links{gap:12px}.nav-link{display:none}.content-wide{padding:32px 20px 24px}.content-wide.challenges{padding-top:0;padding-bottom:48px}.content-narrow{padding:32px 16px 64px}.filter-pills{padding:16px 0}.challenge-row{padding:14px 16px;gap:10px}.track-grid{grid-template-columns:1fr}}@media(max-width:900px){.track-grid{grid-template-columns:repeat(2,1fr)}}