:root {
    --bg: #f7f8fb;
    --surface: #ffffff;
    --text: #1f2937;
    --muted: #6b7280;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-soft: #eff6ff;
    --border: #e5e7eb;
    --success: #059669;
    --error: #dc2626;
    --sidebar: #111827;
    --header-bg: rgba(255, 255, 255, 0.92);
    --header-shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 8px 24px rgba(15, 23, 42, 0.04);
    --radius-pill: 999px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
    width: min(1100px, 92%);
    margin: 0 auto;
    padding: 2rem 0;
}

.site-header, .learn-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: var(--header-bg);
    border-bottom: 1px solid rgba(229, 231, 235, 0.9);
    backdrop-filter: blur(12px);
    box-shadow: var(--header-shadow);
}

.site-header .header-inner,
.learn-header .header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.5rem;
    padding-top: 0.85rem;
    padding-bottom: 0.85rem;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 0.65rem;
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--text);
    letter-spacing: -0.02em;
    text-decoration: none;
    flex-shrink: 0;
}

.logo:hover {
    text-decoration: none;
    color: var(--primary-dark);
}

.logo-mark {
    width: 0.65rem;
    height: 0.65rem;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), #06b6d4);
    box-shadow: 0 0 0 4px var(--primary-soft);
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 1rem;
    min-width: 0;
}

.header-nav-links {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.header-nav-link {
    display: inline-flex;
    align-items: center;
    padding: 0.45rem 0.8rem;
    border-radius: var(--radius-pill);
    color: var(--muted);
    font-size: 0.92rem;
    font-weight: 500;
    text-decoration: none;
    transition: background 0.15s ease, color 0.15s ease;
    white-space: nowrap;
}

.header-nav-link:hover {
    background: #f3f4f6;
    color: var(--text);
    text-decoration: none;
}

.header-nav-link.is-active {
    background: var(--primary-soft);
    color: var(--primary-dark);
}

.header-nav-user {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding-left: 0.85rem;
    border-left: 1px solid var(--border);
    flex-shrink: 0;
}

.user-greeting {
    color: var(--text);
    font-size: 0.88rem;
    white-space: nowrap;
}

.user-greeting::before {
    content: "";
    display: inline-block;
    width: 0.45rem;
    height: 0.45rem;
    margin-right: 0.45rem;
    border-radius: 50%;
    background: var(--success);
    vertical-align: middle;
}

.header-logout {
    display: inline-flex;
    align-items: center;
    padding: 0.45rem 0.85rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    background: var(--surface);
    color: var(--text);
    font: inherit;
    font-size: 0.88rem;
    font-weight: 500;
    cursor: pointer;
    transition: border-color 0.15s ease, background 0.15s ease, color 0.15s ease;
}

.header-logout:hover {
    border-color: #cbd5e1;
    background: #f8fafc;
    color: var(--primary-dark);
}

@media (max-width: 900px) {
    .site-header .header-inner,
    .learn-header .header-inner {
        flex-direction: column;
        align-items: stretch;
    }

    .header-nav {
        flex-direction: column;
        align-items: stretch;
        gap: 0.75rem;
    }

    .header-nav-links {
        justify-content: flex-start;
    }

    .header-nav-user {
        border-left: none;
        padding-left: 0;
        padding-top: 0.75rem;
        border-top: 1px solid var(--border);
        justify-content: space-between;
    }
}

.site-footer {
    margin-top: 3rem;
    padding: 1.5rem 0;
    border-top: 1px solid var(--border);
    color: var(--muted);
}

.hero {
    background: linear-gradient(135deg, #eff6ff, #f0fdf4);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2.5rem;
    margin-bottom: 2rem;
}

.hero h1 { margin-top: 0; }

.button {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 0.65rem 1rem;
    cursor: pointer;
    font: inherit;
}

.button:hover {
    background: var(--primary-dark);
    text-decoration: none;
    color: #fff;
}

.link-button {
    background: none;
    border: none;
    color: var(--primary);
    cursor: pointer;
    font: inherit;
    padding: 0;
}

.link-button.danger { color: var(--error); }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1rem;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1.25rem;
}

.lead { color: var(--muted); font-size: 1.05rem; }
.muted { color: var(--muted); }

.alert {
    padding: 0.85rem 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.alert-success {
    background: #ecfdf5;
    color: var(--success);
    border: 1px solid #a7f3d0;
}

.alert-error {
    background: #fef2f2;
    color: var(--error);
    border: 1px solid #fecaca;
}

.form-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1.5rem;
    display: grid;
    gap: 1rem;
    max-width: 720px;
}

label {
    display: grid;
    gap: 0.35rem;
    font-weight: 600;
}

input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
textarea {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font: inherit;
}

.checkbox {
    font-weight: 400;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.checkbox input { width: auto; }

.inline-form { display: inline; }

.auth-container {
    max-width: 420px;
    margin: 4rem auto;
}

.auth-links {
    margin: 0.25rem 0 0.75rem;
    font-size: 0.95rem;
}

.breadcrumb {
    color: var(--muted);
    margin-bottom: 0.75rem;
}

.unit-list {
    list-style: none;
    padding: 0;
}

.unit-list li {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    margin-bottom: 0.75rem;
}

.unit-list a {
    display: block;
    padding: 1rem;
    color: inherit;
}

.unit-list span {
    display: block;
    color: var(--muted);
    font-size: 0.95rem;
}

.prose {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1.5rem;
}

.practice-sentences {
    display: grid;
    gap: 0.65rem;
    padding-left: 1.35rem;
}

.practice-sentence {
    padding: 0.35rem 0.15rem;
}

.practice-sentence[data-has-media="1"] {
    padding-bottom: 0.55rem;
}

.practice-sentence__media {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.4rem;
}

.practice-sentence__player {
    margin: 0;
}

.practice-sentence__player audio,
.practice-sentence__player video {
    display: block;
    width: 100%;
    max-width: 28rem;
}

.practice-sentence__player--video video {
    max-width: 36rem;
    border-radius: 8px;
    background: #0f172a;
}

.practice-miniplayer {
    display: inline-flex;
    align-items: center;
}

.practice-miniplayer audio {
    display: none;
}

.practice-miniplayer__btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    padding: 0;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: #fff;
    color: var(--primary, #1d4ed8);
    cursor: pointer;
    box-shadow: 0 1px 2px rgba(15, 23, 42, 0.06);
    transition: background 0.15s ease, border-color 0.15s ease, transform 0.15s ease;
}

.practice-miniplayer__btn:hover {
    background: #eff6ff;
    border-color: #93c5fd;
}

.practice-miniplayer__btn:active {
    transform: scale(0.96);
}

.practice-miniplayer.is-playing .practice-miniplayer__btn {
    background: #dbeafe;
    border-color: #60a5fa;
}

.practice-miniplayer__icon {
    display: block;
    width: 0;
    height: 0;
}

.practice-miniplayer__icon--play {
    margin-left: 2px;
    border-style: solid;
    border-width: 6px 0 6px 10px;
    border-color: transparent transparent transparent currentColor;
}

.practice-miniplayer__icon--pause {
    display: none;
    width: 10px;
    height: 12px;
    border-left: 3px solid currentColor;
    border-right: 3px solid currentColor;
    box-sizing: border-box;
}

.practice-miniplayer.is-playing .practice-miniplayer__icon--play {
    display: none;
}

.practice-miniplayer.is-playing .practice-miniplayer__icon--pause {
    display: block;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.unit-nav {
    margin-top: 2rem;
}

.admin-body { background: #eef2f7; }

.admin-layout {
    display: grid;
    grid-template-columns: 240px 1fr;
    min-height: 100vh;
}

.admin-sidebar {
    background: var(--sidebar);
    color: #fff;
    padding: 1.5rem 1rem;
}

.admin-sidebar h2 {
    margin-top: 0;
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    opacity: 0.8;
}

.admin-sidebar nav {
    display: grid;
    gap: 0.5rem;
    margin-top: 1.5rem;
}

.admin-sidebar a,
.admin-sidebar .link-button {
    color: #e5e7eb;
}

.admin-content {
    padding: 2rem;
}

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem;
    display: grid;
    gap: 0.25rem;
}

.stat-card span { color: var(--muted); font-size: 0.9rem; }
.stat-card strong { font-size: 1.6rem; }

.data-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
}

.data-table th,
.data-table td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border);
    text-align: left;
    vertical-align: top;
}

.data-table th {
    background: #f3f4f6;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.admin-section {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1.25rem 1.5rem;
}

@media (max-width: 800px) {
    .admin-layout { grid-template-columns: 1fr; }
    .admin-sidebar nav { grid-template-columns: 1fr 1fr; }
    .page-header { flex-direction: column; }
}

.word-trainer {
    max-width: 640px;
    margin: 0 auto;
}

.trainer-direction {
    display: grid;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.trainer-direction-label {
    color: var(--muted);
    font-size: 0.9rem;
}

.trainer-direction-options {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.trainer-direction-options .button.is-active {
    background: var(--primary-dark);
    color: #fff;
}

.trainer-progress {
    color: var(--muted);
    text-align: center;
    margin-bottom: 1rem;
}

.flashcard {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    min-height: 220px;
    display: grid;
    gap: 1rem;
    align-content: center;
}

.flashcard-label {
    color: var(--muted);
    font-size: 0.85rem;
    margin: 0;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.flashcard-term {
    font-size: 2rem;
    font-weight: 700;
    margin: 0;
}

.flashcard-translation {
    font-size: 1.4rem;
    margin: 0;
}

.flashcard-example {
    color: var(--muted);
    font-style: italic;
}

.trainer-actions {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-top: 1.5rem;
}

.hidden {
    display: none !important;
}

.muted {
    color: var(--muted);
}

.verb-trainer {
    max-width: 640px;
    margin: 0 auto;
}

.trainer-filters {
    display: grid;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.trainer-filter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(11rem, 1fr));
    gap: 0.75rem;
}

.trainer-filter-field {
    display: grid;
    gap: 0.35rem;
    font-size: 0.85rem;
    color: var(--muted);
}

.trainer-filter-field select {
    width: 100%;
    padding: 0.55rem 0.7rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: #fff;
    color: inherit;
}

.trainer-filter-count {
    margin: 0;
    font-size: 0.9rem;
    color: var(--muted);
}

.vocab-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    display: grid;
    gap: 1rem;
    transition: background 0.2s ease, border-color 0.2s ease;
}

.vocab-card.is-correct {
    background: #ecfdf5;
    border-color: #a7f3d0;
}

.vocab-card.is-incorrect {
    background: #fef2f2;
    border-color: #fecaca;
}

.vocab-card .verb-result-badge {
    margin: -0.35rem 0 -0.25rem;
}

.vocab-card.is-correct .verb-result-badge {
    color: var(--success);
}

.vocab-card.is-incorrect .verb-result-badge {
    color: var(--error);
}

.vocab-card.is-correct .verb-correct-hint {
    color: var(--success);
}

.vocab-card.is-incorrect .verb-correct-hint {
    color: #991b1b;
}

.vocab-card.is-correct .verb-answer-input,
.vocab-card.is-incorrect .verb-answer-input {
    background: #fff;
}

.trainer-filter-options {
    display: flex;
    gap: 0.75rem 1rem;
    flex-wrap: wrap;
}

.filter-checkbox {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    cursor: pointer;
}

.trainer-notice {
    color: var(--error);
    text-align: center;
}

.verb-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    display: grid;
    gap: 1.25rem;
    transition: background 0.2s ease, border-color 0.2s ease;
}

.verb-card.is-correct {
    background: #ecfdf5;
    border-color: #a7f3d0;
}

.verb-card.is-incorrect {
    background: #fef2f2;
    border-color: #fecaca;
}

.verb-result-badge {
    margin: -0.35rem 0 -0.25rem;
    text-align: center;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.verb-card.is-correct .verb-result-badge {
    color: var(--success);
}

.verb-card.is-incorrect .verb-result-badge {
    color: var(--error);
}

.verb-correct-hint {
    margin: -0.75rem 0 0;
    font-size: 0.88rem;
    color: #991b1b;
    text-align: center;
}

.verb-prompt {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
    margin: 0;
}

.verb-prompt dt {
    color: var(--muted);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.verb-prompt dd {
    margin: 0.15rem 0 0;
    font-size: 1.1rem;
    font-weight: 600;
}

.verb-answer-label {
    display: grid;
    gap: 0.5rem;
    font-weight: 600;
}

.verb-answer-input {
    width: 100%;
    padding: 0.75rem 0.85rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1.1rem;
}

.verb-answer-input:focus {
    outline: 2px solid #bfdbfe;
    border-color: var(--primary);
}

.verb-card.is-correct .verb-answer-input {
    border-color: #6ee7b7;
    background: #fff;
}

.verb-card.is-incorrect .verb-answer-input {
    border-color: #fca5a5;
    background: #fff;
}

@media (max-width: 600px) {
    .verb-prompt {
        grid-template-columns: 1fr;
    }
}