.header{position:fixed;top:0;left:0;right:0;z-index:100;display:flex;align-items:center;justify-content:space-between;padding:12px 24px;background:#0f1117bf;backdrop-filter:blur(20px);-webkit-backdrop-filter:blur(20px);border-bottom:1px solid var(--border);gap:16px}.header-logo{height:32px;width:auto;flex-shrink:0;object-fit:contain}.header h1{font-size:18px;font-weight:600;letter-spacing:-.3px;background:linear-gradient(135deg,#e8e8ed,#9a9aad);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;white-space:nowrap}.header-link{font-size:13px;color:var(--text-secondary);text-decoration:none;padding:6px 14px;border-radius:8px;border:1px solid var(--border);transition:all .2s;white-space:nowrap}.header-link:hover{background:var(--surface-hover);color:var(--text-primary)}.daily-quiz-btn{display:none;font-size:13px;font-weight:600;color:#fbbf24;text-decoration:none;padding:6px 16px;border-radius:20px;border:1px solid rgba(251,191,36,.3);background:linear-gradient(135deg,#fbbf241f,#f59e0b14);transition:all .25s ease;white-space:nowrap;gap:6px;align-items:center}.daily-quiz-btn.visible{display:inline-flex}.daily-quiz-btn:hover{background:linear-gradient(135deg,#fbbf2440,#f59e0b2e);border-color:#fbbf2480;color:#fcd34d;transform:translateY(-1px);box-shadow:0 4px 16px #fbbf2426}.daily-quiz-btn .quiz-icon{font-size:15px}.quiz-modal-overlay{position:fixed;inset:0;z-index:1000;display:flex;align-items:center;justify-content:center;background:#000000a6;backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);opacity:0;pointer-events:none;transition:opacity .3s ease}.quiz-modal-overlay.open{opacity:1;pointer-events:auto}.quiz-modal-dialog{background:var(--surface, #1e202c);width:92vw;max-width:820px;height:88vh;border-radius:18px;box-shadow:0 24px 80px #0009,0 0 0 1px #fbbf241a;display:flex;flex-direction:column;overflow:hidden;transform:scale(.92) translateY(20px);opacity:0;transition:all .35s cubic-bezier(.16,1,.3,1);border:1px solid var(--border, #2a2d3a)}.quiz-modal-overlay.open .quiz-modal-dialog{transform:scale(1) translateY(0);opacity:1}.quiz-modal-header{padding:14px 20px;border-bottom:1px solid var(--border, #2a2d3a);display:flex;align-items:center;justify-content:space-between;background:linear-gradient(135deg,rgba(251,191,36,.06) 0%,transparent 100%)}.quiz-modal-title{margin:0;font-family:var(--font-main, "Inter", sans-serif);font-size:15px;font-weight:600;color:#fbbf24;display:flex;align-items:center;gap:8px}.quiz-modal-close{background:none;border:none;color:var(--text-secondary, #9ba1b0);font-size:24px;cursor:pointer;padding:4px 8px;line-height:1;transition:all .2s;border-radius:6px}.quiz-modal-close:hover{color:var(--text-primary, #e8e8ed);background:#ffffff1a}.quiz-modal-close:active{transform:scale(.92)}.quiz-modal-body{flex:1;position:relative;overflow:hidden}.quiz-modal-iframe{width:100%;height:100%;border:none;display:block;border-radius:0 0 18px 18px}@media(max-width:600px){.quiz-modal-overlay{align-items:flex-start}.quiz-modal-dialog{width:100vw;height:100vh;height:100dvh;max-width:100vw;border-radius:0;border:none}.quiz-modal-header{padding:10px 12px;padding-top:max(10px,env(safe-area-inset-top,10px));padding-right:max(12px,env(safe-area-inset-right,0px));padding-left:max(12px,env(safe-area-inset-left,0px));gap:8px}.quiz-modal-title{font-size:14px;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.quiz-modal-close{font-size:22px;min-width:44px;min-height:44px;display:flex;align-items:center;justify-content:center;flex-shrink:0}.quiz-modal-iframe{border-radius:0}}.grade-selector{display:flex;align-items:center;gap:6px;flex:1;justify-content:center;overflow-x:auto;scrollbar-width:none}.grade-selector::-webkit-scrollbar{display:none}.grade-selector .grade-label{font-size:11px;font-weight:600;color:var(--text-secondary);text-transform:uppercase;letter-spacing:.8px;margin-right:4px;white-space:nowrap}.grade-pill{font-family:Inter,sans-serif;font-size:12px;font-weight:500;color:var(--text-secondary);background:transparent;border:1px solid var(--border);border-radius:20px;padding:4px 12px;cursor:pointer;transition:all .2s;white-space:nowrap}.grade-pill:hover{background:var(--surface-hover);color:var(--text-primary);border-color:#ffffff26}.grade-pill.active{background:var(--accent);color:var(--accent-text);border-color:var(--accent-border);font-weight:600}.nav-buttons{position:fixed;bottom:28px;left:28px;display:flex;gap:6px;z-index:100}.nav-btn{width:40px;height:40px;border:1px solid var(--border);border-radius:10px;background:#191b23d9;backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);color:var(--text-secondary);font-family:var(--font-main);font-size:16px;cursor:pointer;display:flex;align-items:center;justify-content:center;box-shadow:0 4px 16px #0000004d;transition:all .2s;user-select:none}.nav-btn:hover:not(:disabled){background:var(--surface-hover);color:var(--text-primary);border-color:#ffffff26}.nav-btn:active:not(:disabled){transform:scale(.95)}.nav-btn:disabled{opacity:.3;cursor:not-allowed}.toggle-btn{font-family:var(--font-main);font-size:12px;font-weight:500;color:var(--text-secondary);background:transparent;border:1px solid var(--border);border-radius:8px;padding:6px 14px;cursor:pointer;transition:all .2s;white-space:nowrap;user-select:none}.toggle-btn:hover{background:var(--surface-hover);color:var(--text-primary);border-color:#ffffff26}.toggle-btn.active{background:var(--accent);color:var(--accent-text);border-color:var(--accent-border);font-weight:600}.toggle-btn i{margin-right:4px}.app-status{position:fixed;top:70px;left:20px;z-index:20;max-width:min(440px,calc(100vw - 40px));color:var(--text-primary);padding:12px 18px;background:#191b23d9;backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border:1px solid var(--border);border-radius:10px;font-size:13px;box-shadow:0 4px 20px #0006;pointer-events:none}.theme-selector-container{display:flex;align-items:center;gap:8px;margin-right:auto;border-left:1px solid var(--border);padding-left:16px}.theme-select{font-family:var(--font-main);font-size:12px;font-weight:500;color:var(--text-secondary);background:transparent;border:1px solid var(--border);border-radius:20px;padding:4px 28px 4px 14px;cursor:pointer;transition:all .2s;white-space:nowrap;outline:none;appearance:none;-webkit-appearance:none;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' fill='none'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%239a9aad' stroke-width='1.4' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 10px center}.theme-select:hover{background-color:var(--surface-hover);color:var(--text-primary);border-color:#ffffff26;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' fill='none'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%23e8e8ed' stroke-width='1.4' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 10px center}.theme-select:focus{border-color:var(--accent-border);box-shadow:0 0 0 2px #60a5fa26}.theme-select option{background:var(--bg);color:var(--text-primary);font-size:13px;padding:8px 12px}@media(max-width:767px){.header{padding:10px 12px;gap:8px}.theme-selector-container,.header-link{display:none}}