/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --bg: #f5f5f7;
    --bg-card: #ffffff;
    --bg-nav: #1d1d1f;
    --text: #1d1d1f;
    --text-secondary: #6e6e73;
    --text-nav: #f5f5f7;
    --accent: #0071e3;
    --accent-hover: #0077ED;
    --success: #34c759;
    --danger: #ff3b30;
    --warning: #ff9500;
    --border: #d2d2d7;
    --shadow: 0 2px 12px rgba(0,0,0,0.08);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.2s ease;
    --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', monospace;
}

[data-theme="dark"] {
    --bg: #1d1d1f;
    --bg-card: #2c2c2e;
    --bg-nav: #000000;
    --text: #f5f5f7;
    --text-secondary: #98989d;
    --border: #38383a;
    --shadow: 0 2px 12px rgba(0,0,0,0.3);
}

html { font-size: 16px; scroll-behavior: smooth; }
body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    transition: background var(--transition), color var(--transition);
}

/* === Navigation === */
#navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0 1.5rem;
    height: 56px;
    background: var(--bg-nav);
    color: var(--text-nav);
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    white-space: nowrap;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
    margin-left: 2rem;
}

.nav-link {
    color: var(--text-nav);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    opacity: 0.7;
    transition: opacity var(--transition), background var(--transition);
}

.nav-link:hover, .nav-link.active {
    opacity: 1;
    background: rgba(255,255,255,0.1);
}

#theme-toggle {
    margin-left: auto;
    background: none;
    border: none;
    color: var(--text-nav);
    font-size: 1.3rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: background var(--transition);
}

#theme-toggle:hover { background: rgba(255,255,255,0.1); }

.nav-hamburger {
    display: none;
    background: none;
    border: none;
    color: var(--text-nav);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.25rem;
}

/* === Main === */
#app {
    max-width: 960px;
    margin: 0 auto;
    padding: 2rem 1.5rem 4rem;
}

.page { display: none; }
.page.active { display: block; animation: fadeIn 0.3s ease; }

@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

h1 { font-size: 2rem; font-weight: 700; letter-spacing: -0.02em; margin-bottom: 0.5rem; }
h2 { font-size: 1.5rem; font-weight: 600; margin: 2rem 0 1rem; }
h3 { font-size: 1.15rem; font-weight: 600; margin-bottom: 0.5rem; }

.subtitle { color: var(--text-secondary); font-size: 1.1rem; margin-bottom: 2rem; }

.page-header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 2rem;
}

.controls {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* === Buttons === */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.6rem 1.2rem;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    font-family: var(--font);
}

.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: var(--border); color: var(--text); }
.btn-secondary:hover { background: var(--text-secondary); color: #fff; }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { filter: brightness(1.1); }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { filter: brightness(1.1); }
.btn-flip { background: var(--accent); color: #fff; font-size: 1.1rem; padding: 0.8rem 2rem; }

select {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text);
    font-size: 0.9rem;
    font-family: var(--font);
    cursor: pointer;
}

/* === Dashboard === */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.dash-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
    text-align: center;
}

.dash-card:hover { transform: translateY(-3px); box-shadow: 0 4px 20px rgba(0,0,0,0.12); }
.dash-icon { font-size: 2.5rem; margin-bottom: 0.75rem; }

.dash-progress {
    margin-top: 1rem;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.dash-progress .bar {
    height: 100%;
    background: var(--accent);
    border-radius: 3px;
    transition: width 0.5s ease;
}

.lesson-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 0.75rem;
}

.lesson-tile {
    background: var(--bg-card);
    border-radius: var(--radius-sm);
    padding: 1rem;
    text-align: center;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: transform var(--transition);
    text-decoration: none;
    color: var(--text);
}

.lesson-tile:hover { transform: translateY(-2px); }
.lesson-tile .lesson-num { font-size: 1.5rem; font-weight: 700; color: var(--accent); }
.lesson-tile .lesson-title { font-size: 0.8rem; color: var(--text-secondary); margin-top: 0.25rem; }
.lesson-tile .lesson-progress {
    margin-top: 0.5rem;
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}
.lesson-tile .lesson-progress .bar {
    height: 100%;
    background: var(--success);
    border-radius: 2px;
}

/* === Flashcards === */
.vocab-stats {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.95rem;
}

.stat-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
}

.card-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.flashcard {
    width: 100%;
    max-width: 500px;
    height: 280px;
    perspective: 1000px;
    cursor: pointer;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.5s;
    transform-style: preserve-3d;
}

.flashcard-inner.flipped { transform: rotateY(180deg); }

.flashcard-front, .flashcard-back {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    backface-visibility: hidden;
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    border: 2px solid var(--border);
}

.flashcard-back { transform: rotateY(180deg); }

.card-label {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-secondary);
}

.card-word {
    font-size: 1.8rem;
    font-weight: 700;
    text-align: center;
    line-height: 1.3;
}

.card-hint, .card-forms {
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-align: center;
}

.card-actions {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.card-counter {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* === Grammar === */
.grammar-topic {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.grammar-topic h3 {
    color: var(--accent);
    margin-bottom: 1rem;
}

.grammar-explanation {
    margin-bottom: 1rem;
    line-height: 1.7;
}

.grammar-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
    font-size: 0.9rem;
}

.grammar-table th {
    background: var(--accent);
    color: #fff;
    padding: 0.5rem 0.75rem;
    text-align: left;
    font-weight: 600;
}

.grammar-table td {
    padding: 0.5rem 0.75rem;
    border-bottom: 1px solid var(--border);
}

.grammar-table tr:nth-child(even) td { background: rgba(0,0,0,0.02); }
[data-theme="dark"] .grammar-table tr:nth-child(even) td { background: rgba(255,255,255,0.03); }

.grammar-rules {
    list-style: none;
    margin: 1rem 0;
}

.grammar-rules li {
    padding: 0.4rem 0 0.4rem 1.5rem;
    position: relative;
}

.grammar-rules li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: 700;
}

/* === Exercises === */
.exercise-block {
    background: rgba(0,113,227,0.05);
    border-radius: var(--radius-sm);
    padding: 1.25rem;
    margin-top: 1rem;
    border-left: 3px solid var(--accent);
}

[data-theme="dark"] .exercise-block { background: rgba(0,113,227,0.1); }

.exercise-block h4 {
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    color: var(--accent);
}

.exercise-item {
    margin-bottom: 0.75rem;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
}

.exercise-item input[type="text"] {
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg);
    color: var(--text);
    font-size: 0.9rem;
    font-family: var(--font);
    width: 200px;
}

.exercise-item input.correct { border-color: var(--success); background: rgba(52,199,89,0.1); }
.exercise-item input.wrong { border-color: var(--danger); background: rgba(255,59,48,0.1); }

.exercise-options { display: flex; flex-direction: column; gap: 0.5rem; }

.option-btn {
    padding: 0.6rem 1rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text);
    cursor: pointer;
    text-align: left;
    font-size: 0.9rem;
    font-family: var(--font);
    transition: all var(--transition);
}

.option-btn:hover { border-color: var(--accent); background: rgba(0,113,227,0.05); }
.option-btn.selected { border-color: var(--accent); background: rgba(0,113,227,0.1); }
.option-btn.correct { border-color: var(--success); background: rgba(52,199,89,0.15); }
.option-btn.wrong { border-color: var(--danger); background: rgba(255,59,48,0.15); }

.exercise-feedback {
    font-size: 0.9rem;
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    margin-top: 0.5rem;
}

.exercise-feedback.correct { color: var(--success); }
.exercise-feedback.wrong { color: var(--danger); }

.check-btn {
    margin-top: 0.5rem;
}

/* === Translation === */
.translate-passage {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.translate-passage h3 { color: var(--accent); margin-bottom: 1rem; }

.latin-text {
    font-size: 1.15rem;
    line-height: 2;
    margin-bottom: 1rem;
    font-style: italic;
}

.latin-word {
    cursor: help;
    border-bottom: 1px dotted var(--text-secondary);
    position: relative;
}

.latin-word:hover { color: var(--accent); }

.word-tooltip {
    display: none;
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-nav);
    color: var(--text-nav);
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-style: normal;
    white-space: nowrap;
    z-index: 50;
    pointer-events: none;
}

.latin-word:hover .word-tooltip { display: block; }

.translation-toggle {
    margin-top: 1rem;
}

.translation-text {
    display: none;
    margin-top: 0.75rem;
    padding: 1rem;
    background: rgba(52,199,89,0.08);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--success);
}

.translation-text.visible { display: block; }

/* === Quiz === */
.quiz-container { max-width: 600px; }

.quiz-question {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
}

.quiz-question h4 {
    font-size: 1rem;
    margin-bottom: 1rem;
}

.quiz-question .question-num {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.quiz-explanation {
    display: none;
    margin-top: 0.75rem;
    padding: 0.75rem;
    background: rgba(0,113,227,0.05);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.quiz-explanation.visible { display: block; }

.quiz-score {
    text-align: center;
    padding: 2rem;
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.quiz-score .score-num {
    font-size: 3rem;
    font-weight: 700;
    color: var(--accent);
}

.quiz-progress {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.quiz-progress-bar {
    flex: 1;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.quiz-progress-bar .bar {
    height: 100%;
    background: var(--accent);
    border-radius: 3px;
    transition: width 0.3s ease;
}

.quiz-progress-text {
    font-size: 0.9rem;
    color: var(--text-secondary);
    white-space: nowrap;
}

/* === Responsive === */
@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-links.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 56px;
        left: 0;
        right: 0;
        background: var(--bg-nav);
        padding: 0.5rem;
        box-shadow: var(--shadow);
    }
    .nav-hamburger { display: block; }
    #theme-toggle { margin-left: auto; }

    #app { padding: 1.5rem 1rem 3rem; }
    h1 { font-size: 1.5rem; }
    .page-header { flex-direction: column; align-items: flex-start; }
    .dashboard-grid { grid-template-columns: repeat(2, 1fr); }
    .lesson-grid { grid-template-columns: repeat(3, 1fr); }
    .flashcard { height: 240px; }
    .card-word { font-size: 1.4rem; }
    .card-actions { gap: 0.5rem; }
    .card-actions .btn { padding: 0.5rem 0.8rem; font-size: 0.85rem; }
}

@media (max-width: 480px) {
    .dashboard-grid { grid-template-columns: 1fr; }
    .lesson-grid { grid-template-columns: repeat(2, 1fr); }
}

/* === Utility === */
.hidden { display: none !important; }
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.loading { text-align: center; padding: 3rem; color: var(--text-secondary); }