:root {
  --red: #BA0C2F;
  --blue: #00205B;
  --blue-soft: #e8edf7;
  --bg: #f6f4ef;
  --card: #ffffff;
  --ink: #1d1f24;
  --muted: #646a75;
  --line: #e3e0d8;
  --good: #1f7a4d;
  --good-soft: #e5f4ec;
  --warn: #9a5b00;
  --warn-soft: #fdf1dc;
  --radius: 16px;
  font-size: 18px;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.45;
  -webkit-text-size-adjust: 100%;
}
[hidden] { display: none !important; }
button, input, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }

.logo { font-weight: 800; font-size: 2rem; letter-spacing: -0.02em; color: var(--blue); }
.logo span { color: var(--red); }
.logo.small { font-size: 1.3rem; }
.no { font-weight: 650; }
.en { color: var(--muted); margin: 0.1rem 0 0; font-size: 0.92em; }
.en-inline { color: var(--muted); font-weight: 400; }
.error { color: var(--red); min-height: 1.4em; margin: 0.5rem 0 0; }

button.primary {
  background: var(--blue); color: #fff; border: 0; border-radius: 999px;
  padding: 0.7rem 1.4rem; font-weight: 650;
}
button.primary:disabled { opacity: 0.5; }
button.ghost {
  background: transparent; border: 1px solid var(--line); border-radius: 999px;
  padding: 0.4rem 0.9rem; font-size: 0.85rem; white-space: nowrap;
}
button.ghost[aria-pressed="false"] { color: var(--muted); }
button.subtle { color: var(--muted); }

/* Sign in */
.login { min-height: 100%; display: grid; place-items: center; padding: 1.5rem; }
.login-card {
  background: var(--card); border-radius: 24px; padding: 2.2rem 2rem; width: min(420px, 100%);
  box-shadow: 0 10px 40px rgba(0, 32, 91, 0.08); text-align: center;
}
.login-card h1 { margin: 1.2rem 0 0; font-size: 1.7rem; }
.login-card form { margin-top: 1.6rem; display: grid; gap: 0.6rem; text-align: left; }
.login-card h1 { font-size: 1.35rem; margin: 1rem 0 0; }
.login-card input {
  border: 1px solid var(--line); border-radius: 12px; padding: 0.75rem 0.9rem; font-size: 1rem;
}
.who { display: grid; grid-template-columns: 1fr 1fr; gap: 0.7rem; margin-bottom: 0.6rem; }
.who-btn {
  display: flex; flex-direction: column; align-items: center; gap: 0.5rem;
  background: var(--bg); border: 2px solid var(--line); border-radius: var(--radius);
  padding: 1rem 0.5rem; font-size: 1.15rem; font-weight: 650;
}
.who-btn .flag { height: 2.3rem; width: auto; border-radius: 4px; box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.08); }
.who-btn[aria-checked="true"] { border-color: var(--blue); background: var(--blue-soft); }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.brand { display: flex; align-items: center; gap: 0.6rem; }
.brand .flag { height: 1.2rem; width: auto; border-radius: 3px; box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.08); }
.brand .flag:not([src]) { display: none; }

/* App shell */
.app { height: 100%; height: 100dvh; display: flex; flex-direction: column; max-width: 860px; margin: 0 auto; }
.top {
  display: flex; align-items: center; justify-content: space-between; gap: 0.8rem;
  padding: 0.8rem 1rem; padding-top: max(0.8rem, env(safe-area-inset-top));
  border-bottom: 1px solid var(--line); background: var(--bg);
}
.top nav { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 0.4rem; }

.topics { padding: 1.5rem 1rem; }
.topics h2 { margin: 0; font-size: 1.4rem; }
.topic-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 0.7rem; margin-top: 1.2rem; }
.topic {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 0.9rem; text-align: left;
}
.topic strong { display: block; font-size: 1.05rem; }
.topic span { color: var(--muted); font-size: 0.85rem; }
.topic:hover, .topic:focus-visible { border-color: var(--blue); }

/* Chat */
.chat { flex: 1; overflow-y: auto; padding: 1rem; display: flex; flex-direction: column; gap: 0.9rem; }
.msg { max-width: 88%; }
.msg.me {
  align-self: flex-end; background: var(--blue); color: #fff;
  padding: 0.65rem 0.95rem; border-radius: var(--radius) var(--radius) 4px var(--radius);
  white-space: pre-wrap; overflow-wrap: anywhere;
}
.msg.tutor { align-self: flex-start; display: grid; gap: 0.5rem; min-width: 0; }
.bubble, .feedback { overflow-wrap: anywhere; }
.bubble {
  background: var(--card); border: 1px solid var(--line);
  padding: 0.8rem 1rem; border-radius: var(--radius) var(--radius) var(--radius) 4px;
}
.bubble .no { font-size: 1.2rem; font-weight: 550; }
.bubble .en { margin-top: 0.35rem; }
.hide-english .bubble .en { display: none; }
.hide-english .bubble .reveal { display: inline-block; }
.reveal {
  display: none; margin-top: 0.4rem; background: none; border: 0; padding: 0;
  color: var(--muted); font-size: 0.85rem; text-decoration: underline;
}
.bubble.revealed .en { display: block !important; }
.bubble.revealed .reveal { display: none !important; }

.w {
  border-bottom: 2px dotted rgba(0, 32, 91, 0.25); cursor: pointer; border-radius: 3px;
  -webkit-tap-highlight-color: transparent;
}
.w:hover, .w:focus-visible { background: var(--blue-soft); outline: none; }

.feedback { border-radius: 12px; padding: 0.65rem 0.9rem; font-size: 0.95rem; }
.feedback.correct { background: var(--good-soft); color: var(--good); }
.feedback.small_fix, .feedback.fix { background: var(--warn-soft); }
.feedback.none { background: var(--blue-soft); }
.feedback .label { font-weight: 700; margin-right: 0.3rem; }
.feedback .fixed { font-size: 1.1rem; font-weight: 600; margin: 0.2rem 0 0.3rem; color: var(--ink); }
.feedback .why { color: var(--ink); white-space: pre-wrap; }

.typing { align-self: flex-start; color: var(--muted); padding: 0.4rem 0.2rem; }
.typing span { animation: blink 1.2s infinite both; font-size: 1.6rem; line-height: 0.5; }
.typing span:nth-child(2) { animation-delay: 0.2s; }
.typing span:nth-child(3) { animation-delay: 0.4s; }
@keyframes blink { 0%, 80%, 100% { opacity: 0.2; } 40% { opacity: 1; } }
.chat-error { align-self: center; color: var(--red); font-size: 0.9rem; text-align: center; }
.chat-error button { margin-left: 0.4rem; }

/* Composer */
.composer {
  border-top: 1px solid var(--line); background: var(--bg); padding: 0.6rem 1rem;
  padding-bottom: max(0.6rem, env(safe-area-inset-bottom));
}
.helpers { display: flex; flex-wrap: wrap; gap: 0.35rem; padding-bottom: 0.5rem; }
.helpers button {
  background: var(--card); border: 1px solid var(--line); border-radius: 999px;
  padding: 0.3rem 0.75rem; font-size: 0.85rem; white-space: nowrap;
}
.helpers .keys { display: flex; flex-wrap: wrap; gap: 0.35rem; }
.helpers button[data-insert] { font-weight: 700; min-width: 2.4rem; }
.helpers .spacer { flex: 1; min-width: 0.4rem; }
.send-row { display: flex; gap: 0.5rem; align-items: flex-end; }
.send-row textarea {
  flex: 1; resize: none; border: 1px solid var(--line); border-radius: 14px;
  padding: 0.7rem 0.9rem; font-size: 1.05rem; line-height: 1.4;
  min-height: 5.2rem; max-height: 12rem; background: var(--card);
}
.send-row button { align-self: stretch; border-radius: 14px; }

/* Word card and panels */
.sheet, .panel { position: fixed; inset: 0; z-index: 10; }
.sheet-backdrop { position: absolute; inset: 0; background: rgba(20, 24, 33, 0.35); }
.sheet-body {
  position: absolute; left: 50%; bottom: 0; transform: translateX(-50%);
  width: min(560px, 100%); background: var(--card); border-radius: 22px 22px 0 0;
  max-height: 85dvh; overflow-y: auto;
  padding: 1.4rem 1.4rem max(1.4rem, env(safe-area-inset-bottom));
  box-shadow: 0 -10px 40px rgba(0, 0, 0, 0.12);
}
.close {
  position: absolute; top: 0.6rem; right: 0.8rem; background: none; border: 0;
  font-size: 1.8rem; color: var(--muted); line-height: 1;
}
.word-card h3 { margin: 0; padding-right: 2.5rem; font-size: 1.8rem; color: var(--blue); overflow-wrap: anywhere; }
.word-card .meaning { font-size: 1.15rem; margin: 0.2rem 0 0.8rem; }
.word-card dl { display: grid; grid-template-columns: auto 1fr; gap: 0.35rem 0.9rem; margin: 0 0 1rem; }
.word-card dt { color: var(--muted); font-size: 0.85rem; padding-top: 0.15rem; }
.word-card dd { margin: 0; min-width: 0; overflow-wrap: anywhere; }
.word-card .tag {
  display: inline-block; background: var(--blue-soft); color: var(--blue); border-radius: 999px;
  padding: 0.1rem 0.6rem; font-size: 0.8rem; font-weight: 600;
}
.word-card .saved { color: var(--good); font-weight: 600; }

.panel-body {
  position: absolute; top: 0; right: 0; bottom: 0; width: min(520px, 100%);
  background: var(--card); display: flex; flex-direction: column;
  box-shadow: -10px 0 40px rgba(0, 0, 0, 0.12);
}
.panel-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1rem 1.2rem; padding-top: max(1rem, env(safe-area-inset-top)); border-bottom: 1px solid var(--line);
}
.panel-head h2 { margin: 0; font-size: 1.3rem; }
.panel-head .close { position: static; }
.panel-content { overflow-y: auto; padding: 1rem 1.2rem 2rem; }

details.card { border: 1px solid var(--line); border-radius: 14px; margin-bottom: 0.7rem; background: var(--bg); }
details.card summary { padding: 0.8rem 1rem; font-weight: 650; cursor: pointer; }
details.card .inner { padding: 0 1rem 1rem; }
details.card p { margin: 0 0 0.8rem; }
table.g { border-collapse: collapse; width: 100%; font-size: 0.9rem; margin-bottom: 0.8rem; background: var(--card); display: block; overflow-x: auto; }
table.g th, table.g td { border: 1px solid var(--line); padding: 0.35rem 0.5rem; text-align: left; vertical-align: top; }
table.g th { background: var(--blue-soft); font-weight: 600; }
.ex { margin: 0 0 0.5rem; }
.ex .no { display: block; }
.tip { background: var(--warn-soft); border-radius: 10px; padding: 0.5rem 0.7rem; font-size: 0.9rem; }

.word-row { border-bottom: 1px solid var(--line); padding: 0.75rem 0; display: grid; grid-template-columns: 1fr auto; gap: 0.3rem 0.8rem; }
.word-row .head { font-weight: 650; font-size: 1.1rem; }
.word-row .head span { color: var(--muted); font-weight: 400; font-size: 0.95rem; }
.word-row .forms, .word-row .sent { color: var(--muted); font-size: 0.85rem; grid-column: 1; }
.word-row .del { grid-row: 1 / span 3; grid-column: 2; align-self: start; color: var(--muted); }
.empty { color: var(--muted); }

@media (max-width: 600px) {
  :root { font-size: 17px; }
  .msg { max-width: 94%; }
  /* Phones: logo on its own line, every button visible on the line below. */
  .top {
    flex-direction: column; align-items: stretch; gap: 0.5rem;
    padding: 0.6rem 0.75rem; padding-top: max(0.6rem, env(safe-area-inset-top));
  }
  .top nav { justify-content: flex-start; }
  .top nav button { flex: 1 1 auto; padding: 0.4rem 0.6rem; font-size: 0.8rem; }
  .composer { padding: 0.5rem 0.75rem; padding-bottom: max(0.5rem, env(safe-area-inset-bottom)); }
  .helpers { flex-wrap: wrap; overflow: visible; }
  .helpers .spacer { flex-basis: 100%; height: 0; }
  .helpers button { padding: 0.3rem 0.6rem; font-size: 0.8rem; }
  .helpers button[data-insert] { min-width: 2.2rem; font-size: 1rem; }
  .chat { padding: 0.75rem; }
  .topics { padding: 1rem 0.75rem; }
  .topic-list { grid-template-columns: 1fr 1fr; }
}