:root {
    --primary: #4f6df5;
    --primary-dark: #3a52c4;
    --success: #2fb380;
    --danger: #e6553f;
    --bg: #f4f6fb;
    --card: #ffffff;
    --text: #1f2430;
    --muted: #6b7385;
    --border: #e1e5ef;
    font-size: 17px;
}

* { box-sizing: border-box; }

html { overflow-x: hidden; }
body {
    margin: 0;
    overflow-x: hidden;
    font-family: 'Segoe UI', Roboto, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
}

.topbar {
    background: var(--primary);
    color: #fff;
    padding: 14px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
}

.topbar a { color: #fff; text-decoration: none; }
.topbar .brand { font-weight: 700; font-size: 1.2rem; }
.topbar .nav-right { display: flex; flex-wrap: wrap; row-gap: 6px; gap: 16px; align-items: center; font-size: 0.95rem; }
.topbar .nav-right a:hover { text-decoration: underline; }

.container {
    max-width: 880px;
    margin: 0 auto;
    padding: 24px 16px 60px;
}

.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 20px;
    box-shadow: 0 1px 3px rgba(20, 24, 40, 0.05);
    max-width: 100%;
    overflow-x: auto;
}

h1 { font-size: 1.6rem; margin-top: 0; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1.05rem; }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
}

.lesson-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 18px;
}

.lesson-card h3 { margin: 0 0 6px; }
.lesson-card .meta { color: var(--muted); font-size: 0.88rem; margin-bottom: 12px; }
.lesson-card .actions { display: flex; gap: 8px; flex-wrap: wrap; }

.btn {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 10px 18px;
    font-size: 1rem;
    cursor: pointer;
    text-decoration: none;
    text-align: center;
}
.btn:hover { background: var(--primary-dark); }
.btn.secondary { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn.secondary:hover { background: #eef1ff; }
.btn.danger { background: var(--danger); }
.btn.small { padding: 6px 12px; font-size: 0.88rem; }
.btn:disabled, .btn.disabled { background: #c7cbd6; color: #fff; cursor: not-allowed; pointer-events: none; }

.tabs { display: flex; gap: 8px; margin-bottom: 18px; flex-wrap: wrap; }
.tabs a {
    padding: 8px 16px;
    border-radius: 20px;
    text-decoration: none;
    background: #fff;
    border: 1px solid var(--border);
    color: var(--text);
    font-size: 0.92rem;
}
.tabs a.active { background: var(--primary); color: #fff; border-color: var(--primary); }

form.stacked label { display: block; margin: 12px 0 6px; font-weight: 600; font-size: 0.92rem; }
input[type=text], input[type=password], input[type=number], select, textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--primary); }

.alert { padding: 12px 16px; border-radius: 8px; margin-bottom: 16px; font-size: 0.95rem; }
.alert.error { background: #fdeceb; color: #a3341f; border: 1px solid #f3c3bb; }
.alert.success { background: #e8f8f1; color: #1a7a52; border: 1px solid #b6e8d2; }
.alert.info { background: #eef1ff; color: #3a52c4; border: 1px solid #d3daff; }

.quiz-word { font-size: 2rem; font-weight: 700; text-align: center; margin: 20px 0; display: flex; align-items: center; justify-content: center; gap: 12px; }
.speak-btn {
    background: #eef1ff;
    border: 1px solid var(--border);
    color: var(--primary);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    font-size: 1.3rem;
    cursor: pointer;
    line-height: 1;
    flex-shrink: 0;
}
.speak-btn:hover { background: #dde3ff; }
.speak-btn:disabled { opacity: 0.5; cursor: default; }
.speak-btn.small { width: 30px; height: 30px; font-size: 0.9rem; }

.hint-row { text-align: center; margin: -8px 0 16px; color: var(--muted); font-size: 1rem; }
.hint-row .hint-word { font-weight: 700; letter-spacing: 2px; font-size: 1.3rem; color: var(--text); margin: 0 8px; user-select: none; -webkit-user-select: none; }
.hint-row.solved { color: var(--primary); }
.hint-row.solved .hint-word { color: var(--primary-dark); }
.hint-actions { display: flex; gap: 10px; justify-content: center; margin-top: 14px; }
.quiz-progress { color: var(--muted); text-align: center; margin-bottom: 20px; font-size: 0.9rem; }
.quiz-feedback { text-align: center; font-size: 1.05rem; margin-bottom: 16px; padding: 10px; border-radius: 8px; }
.quiz-feedback.correct { background: #e8f8f1; color: #1a7a52; }
.quiz-feedback.wrong { background: #fdeceb; color: #a3341f; }
.quiz-feedback.info { background: #eef1ff; color: #3a52c4; }
.quiz-input-row { display: flex; gap: 10px; max-width: 420px; margin: 0 auto; }
.quiz-input-row input { flex: 1; text-align: center; font-size: 1.2rem; }

table { width: 100%; border-collapse: collapse; margin-top: 12px; font-size: 0.92rem; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-weight: 600; }
tr:hover td { background: #f9faff; }

.badge { display: inline-block; padding: 3px 10px; border-radius: 12px; font-size: 0.8rem; font-weight: 600; }
.badge.pass { background: #e8f8f1; color: #1a7a52; }
.badge.fail { background: #fdeceb; color: #a3341f; }

.muted { color: var(--muted); }
.stat-row { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 8px; }
.stat-box { background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 16px 20px; flex: 1 1 140px; min-width: 0; }
.stat-box .num { font-size: 1.6rem; font-weight: 700; }
.stat-box .label { color: var(--muted); font-size: 0.85rem; }

.vocab-list { margin-top: 8px; }
.vocab-row {
    display: grid;
    grid-template-columns: 2fr 2fr 1.5fr 90px auto;
    gap: 10px;
    align-items: center;
    padding: 10px 0;
    border-bottom: 1px solid var(--border);
}
.vocab-row.vocab-head { font-size: 0.85rem; color: var(--muted); font-weight: 600; padding-bottom: 8px; }
.vocab-field { min-width: 0; }
.field-with-audio { display: flex; gap: 6px; align-items: center; }
.field-with-audio input { min-width: 0; }
.field-label { display: none; font-size: 0.78rem; color: var(--muted); margin-bottom: 3px; }
.vocab-actions { display: flex; gap: 6px; flex-wrap: wrap; }

@media (max-width: 700px) {
    .vocab-row.vocab-head { display: none; }
    .vocab-row { grid-template-columns: 1fr 1fr; row-gap: 8px; }
    .field-label { display: block; }
    .vocab-actions { grid-column: 1 / -1; }
}

.login-wrap { display: flex; align-items: center; justify-content: center; min-height: 100vh; }
.login-card { max-width: 360px; width: 100%; }

@media (max-width: 600px) {
    .container { padding: 16px 10px 40px; }
    .quiz-word { font-size: 1.5rem; gap: 8px; }
    .card { padding: 16px; }
    .topbar { padding: 12px 14px; }
    .topbar .nav-right { gap: 10px; font-size: 0.88rem; }
    .stat-box { flex-basis: calc(50% - 8px); padding: 12px 14px; }
    table { font-size: 0.82rem; }
    th, td { padding: 6px 6px; }
    .quiz-input-row { flex-wrap: wrap; }
    .quiz-input-row input { flex-basis: 100%; }
    .quiz-input-row button { flex: 1; }
    .hint-actions { flex-wrap: wrap; }
}

@media (max-width: 400px) {
    :root { font-size: 15px; }
    .speak-btn { width: 38px; height: 38px; font-size: 1.1rem; }
}