/* Restore the legacy system-font, narrow-column presentation.
   Learning state and all controls remain owned by the existing application. */
:root{color-scheme:light dark;--bg:#fff;--fg:#1d1d1f;--mute:#6e6e73;--line:#e5e5ea;--card:#f5f5f7;--acc:#0071e3;--accs:rgba(0,113,227,.12);--field:#fff;--error-bg:#fff0ed;--error-fg:#922d20;--focus:#0066cc;--button-fg:#fff}
@media(prefers-color-scheme:dark){:root{color-scheme:dark;--bg:#000;--fg:#f5f5f7;--mute:#98989d;--line:#2c2c2e;--card:#1c1c1e;--acc:#2997ff;--accs:rgba(41,151,255,.18);--field:#101012;--error-bg:#3e201b;--error-fg:#ffd0c7;--focus:#75baff;--button-fg:#071a2c}}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
body{margin:0;background:var(--bg);color:var(--fg);font:18px/1.55 -apple-system,BlinkMacSystemFont,"SF Pro Text","Helvetica Neue",system-ui,sans-serif;-webkit-font-smoothing:antialiased}
[hidden]{display:none!important}a{color:var(--acc);text-decoration:none}a:hover{text-decoration:underline}
.site-header{max-width:402px;margin:0 auto;padding:max(12px,env(safe-area-inset-top)) 22px 0;display:flex;align-items:center;justify-content:space-between;gap:12px}
.brand{font-family:inherit;font-size:15px;line-height:1.3;font-weight:600;color:var(--mute);white-space:nowrap}
nav{display:flex;align-items:center;gap:12px;flex-wrap:wrap;font-size:14px}nav a{min-height:44px;display:inline-flex;align-items:center}nav button{font-size:14px;padding:0 12px;min-height:36px;background:var(--card);color:var(--fg)}
main{max-width:402px;margin:0 auto;padding:24px 22px 32px;min-width:0}
h1{font-size:34px;line-height:1.15;letter-spacing:-.02em;margin:8px 0 2px;font-weight:700}
h2{font-size:22px;line-height:1.25;letter-spacing:-.01em;margin:0 0 12px;font-weight:700}
h3{font-size:20px;line-height:1.3;margin:12px 0}h4{font-size:17px;line-height:1.4;margin:16px 0 8px}
p{overflow-wrap:anywhere;margin:10px 0 14px}.date,.today-date{color:var(--mute);font-size:18px;margin:6px 0 28px}.muted,.sub{color:var(--mute)}
.eyebrow,.section-label,h2.section-heading{font-size:13px;letter-spacing:.06em;text-transform:uppercase;color:var(--mute);margin:28px 0 12px;font-weight:600}
.panel,.tblk,.today-summary{background:var(--card);border:0;border-radius:20px;padding:18px 18px 8px;margin:12px 0}
.tblk h2,.today-summary h2,.panel>h3{font-size:22px;line-height:1.25;font-weight:700;letter-spacing:-.01em;margin:0 0 6px}.tblk .st,.today-summary .st{color:var(--mute);margin:4px 0 14px;font-size:16px}
.panel .panel{background:var(--bg);border:1px solid var(--line);border-radius:16px;padding:16px;margin:18px 0}
button,input,textarea,select{font:inherit}button{font-size:17px;min-height:44px;min-width:44px;border:0;border-radius:999px;padding:8px 20px;background:var(--acc);color:var(--button-fg);cursor:pointer;line-height:1.4;max-width:100%}
button.secondary{background:transparent;color:var(--acc);box-shadow:inset 0 0 0 1px var(--line)}button:disabled{opacity:.5;cursor:not-allowed}
.actions,.btns{display:flex;flex-wrap:wrap;align-items:center;gap:10px;margin:16px 0 2px}
label{display:block;margin:12px 0 6px;font-size:16px}input,textarea,select{display:block;width:100%;min-width:0;max-width:100%;padding:12px 14px;border:1px solid var(--line);border-radius:14px;background:var(--field);color:var(--fg);font-size:17px}
textarea{min-height:100px;resize:vertical}option{color:var(--fg);background:var(--field)}input::placeholder,textarea::placeholder{color:var(--mute);opacity:1}input[type=file]{font-size:14px;padding:10px}input[type=file]::file-selector-button{font:inherit;border:0;border-radius:10px;padding:6px 10px;background:var(--card);color:var(--fg);margin-right:8px}
:focus-visible{outline:3px solid var(--focus);outline-offset:3px}
details{border:1px solid var(--line);border-radius:16px;padding:12px 14px;margin:16px 0;background:var(--bg)}summary{cursor:pointer;font-size:16px;font-weight:500;overflow-wrap:anywhere}summary strong{font-weight:600}details[open]>summary{margin-bottom:12px}
#card-list details{background:var(--card);border-color:transparent}#card-list summary{display:flex;gap:8px;align-items:center;flex-wrap:wrap}#card-list summary strong{flex:1;min-width:100px}.unlearned{color:var(--mute)}.chinese{border-left:2px solid var(--line);padding-left:12px;margin-top:12px}
.pill{display:inline-block;border-radius:999px;background:var(--accs);color:var(--fg);font-size:12px;line-height:1.5;padding:4px 10px;white-space:normal}.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin:16px 0 24px}.metric{background:var(--card);border-radius:16px;padding:12px 14px}.metric strong{display:block;font-size:24px;line-height:1.3}.metric span{font-size:13px;color:var(--mute)}
.mode-note,#status{font-size:14px;line-height:1.5;margin:0 0 14px;color:var(--mute);overflow-wrap:anywhere}.mode-note:empty,#status:empty{display:none}.error,#status.error{padding:12px 14px;border-radius:14px;background:var(--error-bg);color:var(--error-fg)}
#migration{padding:12px 14px;margin:24px 0 16px;font-size:14px}#migration summary{color:var(--acc)}#migration p{font-size:14px}#migration button{font-size:15px}#migration-report{font:13px/1.5 ui-monospace,SFMono-Regular,monospace;white-space:pre-wrap;overflow-wrap:anywhere;max-width:100%;padding:12px;border-radius:12px;background:var(--card)}#migration-report:empty{display:none}
.tmore,.today-more,.more-links{margin-top:28px}.tmore a,.today-more a,.more-links>a{display:block;min-height:44px;padding:6px 0;margin:6px 0 8px;font-size:17px}.tmore details,.today-more details,.more-links details{margin:8px 0}
footer,.tnote{color:var(--mute);font-size:13px;line-height:1.5;border-top:1px solid var(--line);padding-top:16px;margin-top:20px}.page-footer{width:calc(100% - 44px);max-width:358px;margin:0 auto 32px;padding:16px 0 0}
.lesson-content{min-width:0}.lesson-content section{margin:18px 0}.lesson-content audio{display:block;width:100%;max-width:100%;margin:12px 0}.lesson-sentence{padding:4px 0 12px;margin-bottom:12px;border-bottom:1px solid var(--line)}.lesson-sentence [role=button]{cursor:pointer;border-radius:8px;padding:8px;touch-action:manipulation}.sentence-playback.is-current-sentence,.is-current-sentence{background:var(--accs);color:var(--fg);box-shadow:inset 3px 0 var(--acc)}mark{background:var(--accs);color:inherit;font-weight:600;border-radius:4px;padding:0 2px}
.shadow-controls{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:8px 0}.shadow-controls button{font-size:13px;min-height:40px;padding:8px 12px}.shadow-controls span{font-size:13px;color:var(--mute)}.shadow-controls audio{display:none}
@media(max-width:360px){.site-header{padding-left:16px;padding-right:16px;gap:8px}nav{gap:8px}main{padding-left:16px;padding-right:16px}.panel,.tblk,.today-summary{padding:16px}.page-footer{width:auto;margin-left:16px;margin-right:16px}.actions button{padding-left:15px;padding-right:15px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}

/* Keep the mobile composition; allow room on wider browser windows.
   No grid/order placement changes the Review-before-New document order. */
@media(min-width:640px) and (max-width:899px){
  .site-header,main{max-width:720px;padding-left:32px;padding-right:32px}
  .page-footer{width:calc(100% - 64px);max-width:656px}
}
@media(min-width:900px){
  .site-header{max-width:1040px;padding:20px 40px 0}
  main{max-width:1040px;padding:32px 40px 48px}
  .page-footer{width:calc(100% - 80px);max-width:960px;margin-bottom:40px}
  .panel,.tblk,.today-summary{padding:24px 28px 16px}
  .grid{grid-template-columns:repeat(4,minmax(0,1fr))}
  .lesson-content{max-width:70ch;margin-inline:auto}
  .panel p,.panel form{max-width:70ch}
  .lesson-content section{max-width:100%}
  .more-links,.today-more,.tmore{max-width:70ch}
  #migration{max-width:70ch}
  #login{max-width:560px}
  #card-list details{padding:16px 20px}
}

/* Shared legacy course presentation, with the server still owning progress. */
.lesson-step-nav{position:sticky;top:0;z-index:12;width:100%;isolation:isolate;display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:4px;margin:12px -4px;padding:8px 4px;background:var(--card);border-bottom:1px solid var(--line)}
.lesson-step-nav button{font:inherit;font-size:12px;line-height:1.3;min-width:0;min-height:44px;padding:6px 2px;border-radius:10px;white-space:normal;box-shadow:none;background:var(--bg);color:var(--mute)}
.lesson-step-nav button.current{background:var(--acc);color:var(--button-fg);font-weight:600}.lesson-step-nav button:disabled{opacity:1;color:var(--mute);border:1px solid var(--line);cursor:default}
.lesson-bubble{max-width:88%;padding:12px 14px;margin:12px 0;border-radius:18px;background:var(--bg);border:2px solid transparent}.lesson-bubble.speaker-alt,.lesson-bubble[data-speaker-side="alternate"]{margin-left:auto;background:var(--accs)}
.lesson-bubble .speaker,.speaker{display:block;font-size:12px;color:var(--mute);font-weight:600;margin-bottom:4px}.lesson-bubble p{margin:4px 0 8px}.lesson-bubble .is-current-sentence{border-radius:8px}.chunk-mark{background:var(--accs);color:inherit;font-weight:600;border-radius:4px;padding:0 2px}
.player-toolbar,.track-shortcuts{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:12px 0}.player-toolbar button,.track-shortcuts button{font-size:14px;min-height:44px;padding:8px 14px}.track-shortcuts button{background:var(--bg);color:var(--acc);border:1px solid var(--line)}
.lesson-transcript{margin:16px 0;min-width:0}.lesson-transcript[hidden]{display:none!important}.lesson-complete h2{font-size:28px}.lesson-complete>a{display:block;margin:18px 0 10px}
.lookup-example{margin:18px 0}.lookup-example>p{font-size:18px;line-height:1.6}.lookup-audio{margin:8px 0 16px}.lookup-audio>p{font-size:13px;margin:0 0 6px}.lookup-audio audio{display:block;max-width:100%;width:100%}.lookup-usage{background:var(--bg);border-radius:14px;padding:12px 14px;margin-top:18px}.lookup-usage h4{font-size:13px;text-transform:uppercase;letter-spacing:.06em;color:var(--mute);margin:8px 0}.lookup-usage p{font-size:16px;margin:8px 0}.usage-mistake{color:var(--mute)}.usage-correct{color:var(--fg)}
@media(min-width:900px){.lesson-step-nav{max-width:none;margin-inline:0}.lesson-step-nav button{font-size:14px}.lookup-audio audio{max-width:460px}.lesson-bubble{max-width:80%}}

/* Keep sticky navigation opaque and spanning the reading column; scroll targets
   reserve its height so deliberate seek/focus never lands beneath it. */
.lesson-step-nav{box-shadow:0 8px 0 var(--card)}
.lesson-content h3,.lesson-content h4,.lesson-sentence,.lesson-content section{scroll-margin-block-start:100px}
@media(max-width:899px){.lesson-step-nav{margin-inline:0}}
nav[aria-label="Main"] a[aria-current]{font-weight:700;text-decoration:underline;text-underline-offset:4px}