:root {
  --bg: #f5f7fb;
  --panel: #ffffff;
  --ink: #152033;
  --muted: #667085;
  --line: #dce3ee;
  --blue: #2f67e8;
  --blue-deep: #214b9c;
  --blue-soft: #e8f0ff;
  --green: #16a34a;
  --orange: #f59e0b;
  --red: #dc2626;
  --shadow: 0 16px 40px rgba(21, 32, 51, 0.08);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; background: var(--bg); color: var(--ink); }
button, input, select, textarea { font: inherit; }
button { border: 0; cursor: pointer; }
.hidden { display: none !important; }

.login-screen {
  min-height: 100vh;
  display: grid;
  grid-template-columns: minmax(0, 560px) 390px;
  gap: clamp(42px, 5vw, 92px);
  align-items: center;
  justify-content: center;
  padding: 56px clamp(24px, 5vw, 72px);
  background:
    linear-gradient(120deg, rgba(37, 99, 235, .92), rgba(21, 32, 51, .66)),
    radial-gradient(circle at 20% 20%, #ffffff 0, transparent 26%),
    #1d4ed8;
  color: #fff;
}

.brand-kicker { display: flex; gap: 10px; margin-bottom: 28px; }
.brand-kicker span {
  padding: 8px 12px;
  border: 1px solid rgba(255,255,255,.42);
  border-radius: 999px;
  font-size: 13px;
  letter-spacing: .08em;
}
.brand-title { max-width: 520px; font-size: clamp(76px, 10vw, 132px); line-height: .86; font-weight: 850; margin: 0; }
.brand-copy { margin-top: 28px; font-size: 22px; color: rgba(255,255,255,.86); }
.login-card {
  background: rgba(255,255,255,.96);
  color: var(--ink);
  border-radius: 18px;
  box-shadow: var(--shadow);
  padding: 28px;
}
.login-card h2 { margin: 0 0 6px; font-size: 25px; }
.login-card p { margin: 0 0 22px; color: var(--muted); }
.field { display: grid; gap: 8px; margin-bottom: 14px; }
.field label { font-size: 13px; color: var(--muted); font-weight: 650; }
.field input, .field select, .field textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px 13px;
  background: #fff;
  color: var(--ink);
}
.primary, .secondary {
  min-height: 42px;
  border-radius: 12px;
  padding: 0 16px;
  font-weight: 750;
  display: inline-grid;
  place-items: center;
}
.primary { background: var(--blue); color: #fff; }
.secondary { background: var(--blue-soft); color: var(--blue); }
.full { width: 100%; }
.error { color: var(--red); font-size: 13px; min-height: 18px; }

.shell { display: grid; grid-template-columns: 230px minmax(0, 1fr); min-height: 100vh; }
.sidebar {
  background: linear-gradient(160deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #eaf1ff;
  padding: 24px 18px;
  position: sticky;
  top: 0;
  height: 100vh;
}
.side-title { font-size: 24px; font-weight: 850; margin-bottom: 22px; }
.nav { display: grid; gap: 8px; }
.nav button {
  text-align: left;
  color: #dbeafe;
  background: transparent;
  border-radius: 12px;
  padding: 11px 12px;
  font-weight: 720;
}
.nav button.active, .nav button:hover { background: rgba(255,255,255,.12); color: #fff; }
.side-user { margin-top: 28px; padding-top: 18px; border-top: 1px solid rgba(255,255,255,.24); color: #eaf1ff; font-size: 13px; }
.main { padding: 26px clamp(18px, 3vw, 42px) 52px; min-width: 0; }
.topbar { display: flex; justify-content: space-between; gap: 16px; align-items: center; margin-bottom: 22px; }
.topbar h1 { margin: 0; font-size: clamp(24px, 2.6vw, 34px); }
.topbar p { margin: 6px 0 0; color: var(--muted); }

.grid { display: grid; gap: 16px; }
.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: 16px; box-shadow: 0 8px 24px rgba(21,32,51,.04); padding: 18px; }
.task-card, .step-card, .method-card, .feedback-panel { align-content: start; }
.task-card .secondary { margin-top: 10px; }
.step-card p, .method-card p, .feedback-panel p { color: var(--muted); line-height: 1.55; }
.feedback-panel { grid-column: 1 / -1; border-color: rgba(22, 163, 74, .35); background: #f3fbf6; }
.feedback-block {
  border: 1px solid rgba(22, 163, 74, .18);
  border-radius: 12px;
  background: rgba(255,255,255,.72);
  padding: 10px;
  margin-top: 9px;
}
.feedback-block b { display: block; margin-bottom: 4px; }
.feedback-block p { margin: 0; color: var(--ink); }
.training-drill h3 { margin: 12px 0 8px; font-size: 24px; }
.training-drill p { color: var(--muted); line-height: 1.6; }
.media-audio { width: 100%; margin: 10px 0; }
.media-image { display: block; max-width: 100%; max-height: 320px; object-fit: contain; margin: 10px 0; border-radius: 12px; border: 1px solid var(--line); background: #fff; }
.drill-material { background: #f8fbff; }
.article-panel { display: grid; gap: 10px; }
.article-paragraph { margin: 0; color: var(--ink) !important; }
.article-image {
  display: block;
  width: 100%;
  max-height: 520px;
  object-fit: contain;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
}
.paragraph-number {
  display: inline-grid;
  place-items: center;
  width: 24px;
  height: 24px;
  margin-right: 8px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 800;
  font-size: 12px;
}
.interaction-panel {
  border: 1px solid rgba(47, 103, 232, .24);
  background: #f8fbff;
  border-radius: 12px;
  padding: 12px;
  display: grid;
  gap: 6px;
}
.interaction-panel p { margin: 0; color: var(--ink); }
.interaction-panel small { color: var(--muted); font-weight: 700; }
.choice-list, .choice-picker { display: grid; gap: 9px; }
.choice-row, .choice-pick {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 10px;
  align-items: start;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  padding: 10px;
  text-align: left;
}
.choice-row p, .choice-pick span { margin: 0; color: var(--ink); line-height: 1.5; min-width: 0; }
.choice-name, .choice-pick strong {
  display: inline-grid;
  place-items: center;
  min-width: 28px;
  height: 28px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 850;
}
.choice-pick:hover { border-color: var(--blue); background: #f8fbff; }
.empty-bank p { color: var(--muted); line-height: 1.6; max-width: 760px; }
.metric { display: grid; gap: 8px; }
.metric span { color: var(--muted); font-size: 13px; }
.metric strong { font-size: 28px; }
.section-title { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin: 26px 0 12px; }
.section-title h2 { margin: 0; font-size: 20px; }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; }
.tag { border-radius: 999px; padding: 6px 10px; background: #eef2ff; color: #3730a3; font-size: 13px; font-weight: 700; }
.source-label { display: inline-block; margin-left: 8px; color: var(--muted); font-size: 13px; font-weight: 700; }
.form-chip-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 10px; }
.form-chip {
  min-height: 82px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  padding: 11px;
  text-align: left;
  display: grid;
  align-content: space-between;
  gap: 5px;
}
.form-chip span { color: var(--muted); font-size: 12px; font-weight: 750; }
.form-chip strong { color: var(--ink); font-size: 14px; line-height: 1.25; }
.form-chip em { color: var(--blue); font-style: normal; font-size: 12px; font-weight: 850; }
.form-chip:hover { border-color: var(--blue); background: #f8fbff; }
.list { display: grid; gap: 10px; }
.item { padding: 12px; border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.item strong { display: block; margin-bottom: 5px; }
.item small { color: var(--muted); }
.progress { height: 9px; background: #e5e7eb; border-radius: 999px; overflow: hidden; }
.progress i { display: block; height: 100%; background: var(--green); border-radius: inherit; }
.form-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.form-grid .wide { grid-column: 1 / -1; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.blank-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 10px; }
.source-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
.source-tile {
  min-height: 86px;
  border-radius: 14px;
  padding: 14px;
  color: #fff;
  display: grid;
  align-content: space-between;
  box-shadow: 0 8px 20px rgba(21, 32, 51, .08);
}
.source-tile strong { font-size: 18px; }
.source-tile span { font-weight: 800; opacity: .9; }
.source-tile.reading { background: linear-gradient(135deg, #78a80d, #3f7f13); }
.source-tile.listening { background: linear-gradient(135deg, #fbbf24, #f97316); }
.source-tile.writing { background: linear-gradient(135deg, #14d7c6, #0891b2); }
.source-tile.speaking { background: linear-gradient(135deg, #fb7bad, #be185d); }
.mobile-top { display: none; }

@media (max-width: 900px) {
  .login-screen { grid-template-columns: 1fr; gap: 28px; padding: 38px 18px; }
  .brand-title { font-size: clamp(58px, 20vw, 92px); }
  .shell { display: block; }
  .sidebar { display: none; }
  .mobile-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 16px;
    background: linear-gradient(160deg, var(--blue) 0%, var(--blue-deep) 100%);
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 3;
  }
  .mobile-menu { position: fixed; inset: 58px 12px auto; background: #fff; color: var(--ink); border-radius: 16px; box-shadow: var(--shadow); padding: 12px; z-index: 4; }
  .mobile-menu .nav button { color: var(--ink); }
  .main { padding: 18px 14px 42px; }
  .cols-4, .cols-3, .cols-2, .form-grid, .source-grid, .form-chip-grid { grid-template-columns: 1fr; }
  .blank-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}