*,:after,:before{box-sizing:border-box;margin:0;padding:0}:root{--color-bg:#f8fafc;--color-surface:#ffffff;--color-surface-2:#f1f5f9;--color-primary:#4f46e5;--color-primary-hov:#4338ca;--color-primary-bg:#eef2ff;--color-highlight:#fde047;--color-text:#0f172a;--color-text-2:#475569;--color-text-3:#94a3b8;--color-border:#e2e8f0;--color-error:#ef4444;--color-error-bg:#fef2f2;--radius:10px;--radius-lg:16px;--shadow-sm:0 1px 2px 0 rgb(0 0 0/.05);--shadow:0 1px 3px 0 rgb(0 0 0/.1),0 1px 2px -1px rgb(0 0 0/.1);--shadow-md:0 4px 6px -1px rgb(0 0 0/.1),0 2px 4px -2px rgb(0 0 0/.1);--t:150ms ease}html{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,system-ui,sans-serif;font-size:16px;-webkit-font-smoothing:antialiased}body{background:var(--color-bg);color:var(--color-text);line-height:1.6;min-height:100vh;display:flex;flex-direction:column}a{color:var(--color-primary);text-decoration:none;transition:color var(--t)}a:hover{text-decoration:underline}.site-header{background:var(--color-surface);border-bottom:1px solid var(--color-border);padding:0 24px;height:58px;justify-content:space-between;position:-webkit-sticky;position:sticky;top:0;z-index:10;flex-shrink:0}.site-header,.site-logo{display:flex;align-items:center}.site-logo{font-size:17px;font-weight:700;color:var(--color-primary);letter-spacing:-.02em;gap:8px}.site-logo:hover{text-decoration:none}.site-logo-icon{width:28px;height:28px;background:var(--color-primary-bg);border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:16px}.site-nav{display:flex;gap:2px}.site-nav a{color:var(--color-text-2);font-size:14px;font-weight:500;padding:6px 12px;border-radius:7px;transition:all var(--t)}.site-nav a:hover{color:var(--color-text);background:var(--color-surface-2);text-decoration:none}.site-main{flex:1 1;max-width:700px;width:100%;margin:0 auto;padding:36px 24px 80px}.site-footer{text-align:center;padding:20px 24px;color:var(--color-text-3);font-size:13px;border-top:1px solid var(--color-border)}.hero{margin-bottom:28px}.hero-badge{display:inline-flex;align-items:center;gap:6px;background:var(--color-primary-bg);color:var(--color-primary);font-size:11px;font-weight:700;padding:4px 10px;border-radius:99px;margin-bottom:14px;letter-spacing:.05em;text-transform:uppercase}.hero h1{font-size:28px;font-weight:800;line-height:1.25;margin-bottom:10px;letter-spacing:-.02em}.hero p{font-size:16px;margin-bottom:16px;max-width:520px}.hero p,.hero-cta{color:var(--color-text-2)}.hero-cta{display:inline-flex;align-items:center;gap:6px;font-size:14px;font-weight:500;padding:6px 0;border-bottom:1px solid transparent;transition:all var(--t)}.hero-cta:hover{color:var(--color-primary);border-bottom-color:var(--color-primary);text-decoration:none}.tts-player{background:var(--color-surface);border:1px solid var(--color-border);border-radius:var(--radius-lg);padding:24px;box-shadow:var(--shadow)}.input-hdr{display:flex;align-items:baseline;justify-content:space-between;margin-bottom:7px}.form-label{font-size:12px;font-weight:700;color:var(--color-text-2);letter-spacing:.05em;text-transform:uppercase}.char-count{font-size:12px;color:var(--color-text-3);transition:color var(--t);font-feature-settings:"tnum";font-variant-numeric:tabular-nums}.char-count.over{color:var(--color-error);font-weight:700}textarea.tts-input{width:100%;min-height:140px;padding:12px 14px;font-size:15px;font-family:inherit;line-height:1.65;border:1.5px solid var(--color-border);border-radius:var(--radius);background:var(--color-surface);color:var(--color-text);resize:vertical;transition:border-color var(--t),box-shadow var(--t);outline:none}textarea.tts-input::placeholder{color:var(--color-text-3)}textarea.tts-input:focus{border-color:var(--color-primary);box-shadow:0 0 0 3px var(--color-primary-bg)}textarea.tts-input.over-limit{border-color:var(--color-error)}.controls-section{margin-top:18px;display:grid;grid-gap:14px;gap:14px}.voice-row{display:flex;gap:10px}.control-group{display:flex;flex-direction:column;gap:6px;flex:1 1;min-width:0}select.select-field{-webkit-appearance:none;-moz-appearance:none;appearance:none;background-color:var(--color-surface);background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 16 16'%3E%3Cpath d='M3 6l5 5 5-5' stroke='%2394a3b8' stroke-width='1.5' fill='none' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 10px center;background-size:16px;padding:9px 34px 9px 12px;font-size:14px;font-family:inherit;border:1.5px solid var(--color-border);border-radius:var(--radius);color:var(--color-text);cursor:pointer;transition:border-color var(--t);outline:none;width:100%}select.select-field:focus{border-color:var(--color-primary)}select.select-field:hover{border-color:var(--color-text-3)}.speed-pills{display:flex;gap:6px;flex-wrap:wrap;margin-top:2px}.speed-pill{padding:7px 14px;font-size:13px;font-weight:500;border-radius:99px;border:1.5px solid var(--color-border);background:var(--color-surface);color:var(--color-text-2);cursor:pointer;transition:all var(--t);font-family:inherit;line-height:1}.speed-pill.active,.speed-pill:hover{border-color:var(--color-primary);color:var(--color-primary);background:var(--color-primary-bg)}.speed-pill.active{font-weight:700}.action-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:4px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;padding:10px 20px;font-size:14px;font-weight:600;font-family:inherit;border-radius:var(--radius);border:1.5px solid transparent;cursor:pointer;transition:all var(--t);line-height:1;white-space:nowrap;text-decoration:none}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-primary{background:var(--color-primary);color:#fff;border-color:var(--color-primary);flex:1 1}.btn-primary:hover:not(:disabled){background:var(--color-primary-hov);border-color:var(--color-primary-hov);text-decoration:none}.btn-secondary{background:var(--color-surface);color:var(--color-text-2);border-color:var(--color-border)}.btn-secondary:hover:not(:disabled){background:var(--color-surface-2);color:var(--color-text);border-color:var(--color-text-3);text-decoration:none}.btn-active{background:var(--color-primary-bg);color:var(--color-primary);border-color:var(--color-primary)}.btn-active:hover:not(:disabled){background:var(--color-primary-bg);color:var(--color-primary-hov);border-color:var(--color-primary-hov)}.btn-icon{font-size:15px}.alert-error{display:flex;gap:8px;align-items:flex-start;background:var(--color-error-bg);border:1px solid #fca5a5;color:var(--color-error);padding:10px 14px;border-radius:var(--radius);font-size:14px;margin-top:14px}.audio-wrap{margin-top:16px}.audio-wrap audio{width:100%;border-radius:8px;display:block}.tts-divider{border:none;border-top:1px solid var(--color-border);margin:18px 0}.karaoke-wrap{background:#1e293b;border-radius:var(--radius);padding:18px 20px;max-height:280px;overflow-y:auto;line-height:2;font-size:15.5px;white-space:pre-wrap;word-break:break-word;position:relative;scroll-behavior:smooth}.karaoke-wrap::-webkit-scrollbar{width:4px}.karaoke-wrap::-webkit-scrollbar-track{background:transparent}.karaoke-wrap::-webkit-scrollbar-thumb{background:#334155;border-radius:4px}.karaoke-word{border-radius:3px;transition:color 80ms,background 80ms}.karaoke-word.read{color:#64748b}.karaoke-word.active{background:var(--color-highlight);color:#1e293b;font-weight:700;padding:0 1px}.karaoke-word.unread{color:#e2e8f0}.karaoke-gap{color:#94a3b8}.playlist-start{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;margin-bottom:16px}.playlist-wrap{border:1px solid rgba(79,70,229,.25);border-radius:var(--radius);overflow:hidden;margin-bottom:18px}.playlist-bar{display:flex;align-items:center;gap:10px;padding:10px 14px;background:var(--color-primary-bg);font-size:13px;color:var(--color-primary);font-weight:500}.playlist-chip{font-size:10px;font-weight:800;letter-spacing:.05em;text-transform:uppercase;background:var(--color-primary);color:#fff;padding:2px 8px;border-radius:99px;flex-shrink:0}.playlist-prog{flex:1 1;height:4px;background:rgba(79,70,229,.15);border-radius:99px;overflow:hidden;min-width:40px}.playlist-prog-fill{height:100%;background:var(--color-primary);border-radius:99px;transition:width .5s ease}.playlist-done{color:#10b981;font-weight:600}.playlist-list-btn{border:none;background:none;color:var(--color-primary);font-size:12px;font-weight:700;cursor:pointer;font-family:inherit;padding:3px 8px;border-radius:6px;transition:background var(--t);white-space:nowrap;flex-shrink:0}.playlist-list-btn:hover{background:rgba(79,70,229,.15)}.playlist-list{border-top:1px solid rgba(79,70,229,.15);max-height:300px;overflow-y:auto;background:var(--color-surface)}.playlist-list::-webkit-scrollbar{width:4px}.playlist-list::-webkit-scrollbar-thumb{background:var(--color-border);border-radius:4px}.playlist-item{display:flex;align-items:center;gap:12px;padding:11px 14px;font-size:14px;color:var(--color-text-2);cursor:pointer;border:none;background:var(--color-surface);width:100%;text-align:left;font-family:inherit;transition:background var(--t);border-bottom:1px solid var(--color-border)}.playlist-item:last-child{border-bottom:none}.playlist-item:hover{background:var(--color-surface-2)}.playlist-item.active{background:var(--color-primary-bg);color:var(--color-primary);font-weight:600}.playlist-item-num{font-size:11px;font-weight:700;min-width:20px;color:var(--color-text-3)}.playlist-item.active .playlist-item-num{color:var(--color-primary)}.playlist-item-icon{font-size:12px;flex-shrink:0;width:16px;text-align:center}.page-hdr{margin-bottom:24px}.page-hdr h1{font-size:24px;font-weight:800;letter-spacing:-.02em;margin-bottom:6px}.page-hdr p{font-size:15px;color:var(--color-text-2)}.lessons-grid{display:grid;grid-gap:8px;gap:8px}.lesson-card{display:flex;align-items:center;gap:14px;padding:14px 16px;background:var(--color-surface);border:1.5px solid var(--color-border);border-radius:var(--radius);text-decoration:none;color:var(--color-text);transition:all var(--t);box-shadow:var(--shadow-sm)}.lesson-card:hover{border-color:var(--color-primary);box-shadow:var(--shadow-md);transform:translateY(-1px);text-decoration:none}.lesson-num{font-size:12px;font-weight:800;color:var(--color-primary);background:var(--color-primary-bg);min-width:32px;height:32px;border-radius:8px;display:flex;align-items:center;justify-content:center;flex-shrink:0}.lesson-title{font-size:15px;font-weight:500;flex:1 1}.lesson-arrow{color:var(--color-text-3);font-size:16px;flex-shrink:0}.breadcrumb{display:flex;align-items:center;gap:6px;margin-bottom:18px;font-size:13px;color:var(--color-text-3)}.breadcrumb a{color:var(--color-text-2)}.breadcrumb a:hover{color:var(--color-primary);text-decoration:none}.breadcrumb-sep{color:var(--color-border)}.lesson-heading{font-size:22px;font-weight:800;letter-spacing:-.02em;margin-bottom:20px;line-height:1.3}.page-nav{display:flex;gap:10px;margin-top:24px;padding-top:20px;border-top:1px solid var(--color-border)}.page-nav-link{flex:1 1;display:flex;flex-direction:column;gap:3px;padding:12px 14px;background:var(--color-surface);border:1.5px solid var(--color-border);border-radius:var(--radius);color:var(--color-text);text-decoration:none;transition:all var(--t);box-shadow:var(--shadow-sm)}.page-nav-link:hover{border-color:var(--color-primary);box-shadow:var(--shadow-md);text-decoration:none}.page-nav-link.next{align-items:flex-end}.page-nav-label{font-size:11px;font-weight:700;letter-spacing:.05em;text-transform:uppercase;color:var(--color-text-3)}.page-nav-title{font-size:14px;font-weight:500;color:var(--color-text)}.page-nav-placeholder{flex:1 1}@media (max-width:640px){.site-header{padding:0 16px}.site-main{padding:24px 16px 60px}.hero h1{font-size:22px}.tts-player{padding:18px 16px}.action-row,.voice-row{flex-direction:column}.action-row .btn{width:100%}.speed-pills{gap:5px}.speed-pill{padding:6px 12px;font-size:12px}.page-nav{flex-direction:column}}