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

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #7c3aed;
    --success: #16a34a;
    --error: #dc2626;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-400: #9ca3af;
    --gray-600: #4b5563;
    --gray-800: #1f2937;
    --radius: 10px;
    --shadow: 0 1px 3px rgba(0,0,0,.08), 0 4px 12px rgba(0,0,0,.06);
    --shadow-md: 0 4px 6px rgba(0,0,0,.07), 0 8px 24px rgba(0,0,0,.08);
}

html { font-size: 16px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #fff;
    color: var(--gray-800);
    line-height: 1.6;
    min-height: 100vh;
}

/* ── Header ───────────────────────────────────────────────── */
header {
    border-bottom: 1px solid var(--gray-200);
    padding: 0 1.5rem;
    background: #fff;
    position: sticky;
    top: 0;
    z-index: 10;
}
.header-inner {
    max-width: 860px;
    margin: 0 auto;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.logo {
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--primary);
    text-decoration: none;
    letter-spacing: -.02em;
}
.header-right { display: flex; align-items: center; gap: .75rem; }
.user-badge {
    background: var(--gray-100);
    padding: .25rem .75rem;
    border-radius: 999px;
    font-size: .85rem;
    color: var(--gray-600);
    font-weight: 500;
}

/* ── Main ─────────────────────────────────────────────────── */
main { padding: 2rem 1.5rem; }
.page { max-width: 860px; margin: 0 auto; }
.page-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: 2rem;
    gap: 1rem;
    flex-wrap: wrap;
}
.page-header h1 { font-size: 1.6rem; font-weight: 700; }
.subtitle { color: var(--gray-600); font-size: .95rem; }

/* ── Buttons ──────────────────────────────────────────────── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: .4rem;
    padding: .5rem 1rem;
    border-radius: var(--radius);
    font-size: .9rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    border: 1.5px solid transparent;
    transition: all .15s;
    white-space: nowrap;
}
.btn:hover { filter: brightness(.94); }
.btn-primary { background: var(--primary); color: #fff; }
.btn-secondary { background: var(--secondary); color: #fff; }
.btn-outline { background: transparent; border-color: var(--gray-200); color: var(--gray-800); }
.btn-outline:hover { background: var(--gray-50); }
.btn-success { background: var(--success); color: #fff; }
.btn-error { background: var(--error); color: #fff; }
.btn-sm { padding: .35rem .75rem; font-size: .82rem; }
.btn-lg { padding: .7rem 1.4rem; font-size: 1rem; }

/* ── Center box (login) ───────────────────────────────────── */
.center-box {
    max-width: 400px;
    margin: 5rem auto;
    text-align: center;
}
.center-box h1 { font-size: 1.8rem; margin-bottom: .5rem; }
.center-box .subtitle { color: var(--gray-600); margin-bottom: 2rem; }
.name-form { display: flex; flex-direction: column; gap: .75rem; }
.name-form input {
    padding: .75rem 1rem;
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 1rem;
    outline: none;
    transition: border-color .15s;
}
.name-form input:focus { border-color: var(--primary); }

/* ── Lists grid ──────────────────────────────────────────── */
.lists-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1rem;
}
.list-card {
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-shadow: var(--shadow);
    transition: box-shadow .15s;
}
.list-card:hover { box-shadow: var(--shadow-md); }
.list-card-header { margin-bottom: 1rem; }
.list-card-header h2 { font-size: 1rem; font-weight: 600; margin-bottom: .25rem; }
.lang-badge {
    background: var(--gray-100);
    color: var(--gray-600);
    padding: .15rem .6rem;
    border-radius: 999px;
    font-size: .78rem;
    font-weight: 500;
}
.list-card-actions { display: flex; gap: .5rem; flex-wrap: wrap; }

/* ── Stats ────────────────────────────────────────────────── */
.stats-row { display: flex; gap: .75rem; margin-bottom: 1.25rem; flex-wrap: wrap; }
.stat-card {
    flex: 1;
    min-width: 80px;
    background: var(--gray-50);
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1rem;
    text-align: center;
}
.stat-card.learned { border-color: #bbf7d0; background: #f0fdf4; }
.stat-card.review { border-color: #fed7aa; background: #fff7ed; }
.stat-card.new { border-color: #bfdbfe; background: #eff6ff; }
.stat-num { font-size: 1.8rem; font-weight: 700; }
.stat-label { font-size: .8rem; color: var(--gray-600); margin-top: .1rem; }

.progress-bar-wrap {
    height: 8px;
    background: var(--gray-200);
    border-radius: 999px;
    overflow: hidden;
    margin-bottom: .5rem;
}
.progress-bar {
    height: 100%;
    background: var(--success);
    border-radius: 999px;
    transition: width .4s ease;
}
.progress-label { font-size: .85rem; color: var(--gray-600); margin-bottom: 1.5rem; }

.action-row { display: flex; gap: .75rem; flex-wrap: wrap; }

/* ── Card / Form ──────────────────────────────────────────── */
.card {
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.25rem;
    box-shadow: var(--shadow);
}
.info-card { background: var(--gray-50); }
.info-card h3 { font-size: 1rem; margin-bottom: .75rem; }
.info-card pre {
    background: var(--gray-200);
    padding: .75rem;
    border-radius: 6px;
    font-size: .85rem;
    margin-bottom: .75rem;
}

.form-group { margin-bottom: 1rem; }
.form-group label { display: block; font-size: .9rem; font-weight: 500; margin-bottom: .4rem; }
.form-group input[type=text], .form-group input[type=file] {
    width: 100%;
    padding: .65rem .9rem;
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: .95rem;
    outline: none;
    transition: border-color .15s;
}
.form-group input[type=text]:focus { border-color: var(--primary); }
.form-group small { display: block; margin-top: .35rem; font-size: .8rem; color: var(--gray-600); }

/* ── Alerts ───────────────────────────────────────────────── */
.alert {
    padding: .85rem 1.1rem;
    border-radius: var(--radius);
    margin-bottom: 1.25rem;
    font-size: .9rem;
}
.alert-error { background: #fef2f2; border: 1px solid #fecaca; color: var(--error); }
.alert-success { background: #f0fdf4; border: 1px solid #bbf7d0; color: var(--success); }

/* ── Flashcard ────────────────────────────────────────────── */
.fc-container { max-width: 560px; margin: 0 auto; }
.fc-progress { display: flex; align-items: center; gap: 1rem; margin-bottom: 1.5rem; }
.fc-progress-bar { flex: 1; height: 6px; background: var(--gray-200); border-radius: 999px; overflow: hidden; }
.fc-progress-bar > div { height: 100%; background: var(--primary); border-radius: 999px; transition: width .3s; }

.fc-card {
    perspective: 1000px;
    height: 240px;
    cursor: pointer;
    margin-bottom: 1.5rem;
    user-select: none;
    transition: opacity .14s ease;
}
.fc-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform .45s ease;
}
.fc-inner.flipped { transform: rotateY(180deg); }
.fc-front, .fc-back {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    border: 1.5px solid var(--gray-200);
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    background: #fff;
}
.fc-back { transform: rotateY(180deg); background: var(--gray-50); }
.fc-lang { font-size: .78rem; font-weight: 600; letter-spacing: .08em; text-transform: uppercase; color: var(--gray-400); margin-bottom: .5rem; }
.fc-word { font-size: 2rem; font-weight: 700; text-align: center; }
.fc-hint { font-size: .78rem; color: var(--gray-400); margin-top: 1rem; }

.fc-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* ── Write mode ────────────────────────────────────────────── */
.write-container { max-width: 560px; margin: 0 auto; }
.write-card {
    border: 1.5px solid var(--gray-200);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    margin-bottom: 1.5rem;
}
.write-question { font-size: 2rem; font-weight: 700; margin: .5rem 0 1rem; }
.write-form {
    display: flex;
    gap: .75rem;
    flex-wrap: wrap;
    margin-top: .5rem;
}
.write-form input[type=text] {
    flex: 1;
    min-width: 160px;
    padding: .65rem .9rem;
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 1rem;
    outline: none;
    transition: border-color .15s;
}
.write-form input[type=text]:focus { border-color: var(--primary); }
.write-form input.input-correct { border-color: var(--success); background: #f0fdf4; }
.write-form input.input-wrong   { border-color: var(--error);   background: #fef2f2; }

/* .write-card fade */
.write-card { transition: opacity .14s ease; }
.w-feedback {
    margin-top: .75rem;
    padding: .65rem .9rem;
    border-radius: var(--radius);
    font-size: .95rem;
    font-weight: 500;
}
.w-feedback.correct { background: #f0fdf4; color: var(--success); border: 1px solid #bbf7d0; }
.w-feedback.wrong { background: #fef2f2; color: var(--error); border: 1px solid #fecaca; }

/* ── Done screen ──────────────────────────────────────────── */
.done-screen {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1rem;
    padding: 2rem;
    border: 1.5px solid var(--gray-200);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}
.done-screen h2 { font-size: 1.6rem; }
.done-actions { display: flex; gap: .75rem; flex-wrap: wrap; justify-content: center; margin-top: .5rem; }

/* ── History table ────────────────────────────────────────── */
.error-table { width: 100%; border-collapse: collapse; }
.error-table th, .error-table td {
    padding: .75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
    font-size: .9rem;
}
.error-table th { font-weight: 600; background: var(--gray-50); }
.error-count {
    background: #fef2f2;
    color: var(--error);
    font-weight: 700;
    padding: .1rem .5rem;
    border-radius: 999px;
}
.badge { padding: .15rem .6rem; border-radius: 999px; font-size: .78rem; font-weight: 600; }
.badge-learned { background: #f0fdf4; color: var(--success); }
.badge-review { background: #fff7ed; color: #c2410c; }

/* ── Empty state ──────────────────────────────────────────── */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--gray-600);
}
.empty-state p { margin-bottom: 1rem; }

/* ── User picker ──────────────────────────────────────────── */
.user-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(96px, 1fr));
    gap: .75rem;
    margin: 1.5rem 0;
}
.user-card-btn {
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: .5rem;
    padding: 1rem .5rem;
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    background: #fff;
    cursor: pointer;
    transition: border-color .15s, box-shadow .15s;
}
.user-card-btn:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-md);
}
.user-avatar {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: #fff;
    font-size: 1.4rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
}
.user-name { font-size: .85rem; font-weight: 500; color: var(--gray-800); }
.new-user-toggle { margin-top: .5rem; }

/* ── Direction toggle on card ─────────────────────────────── */
.dir-switch {
    position: absolute;
    top: .75rem;
    right: .75rem;
    background: var(--gray-100);
    border: 1.5px solid var(--gray-200);
    border-radius: 6px;
    padding: .25rem .55rem;
    font-size: .88rem;
    font-weight: 700;
    cursor: pointer;
    color: var(--gray-600);
    transition: background .12s, color .12s;
    z-index: 2;
    line-height: 1.4;
}
.dir-switch:hover { background: var(--primary); color: #fff; border-color: var(--primary); }
.dir-switch.dir-active { background: var(--primary); color: #fff; border-color: var(--primary); }
.dir-label {
    font-size: .78rem;
    font-weight: 600;
    color: var(--gray-400);
    white-space: nowrap;
    letter-spacing: .02em;
}

/* .write-card needs position:relative for the absolute dir-switch */
.write-card { position: relative; }

/* ── Session config ───────────────────────────────────────── */
.session-config {
    background: var(--gray-50);
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: .9rem;
}
.config-row {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}
.config-label {
    font-size: .82rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: .06em;
    color: var(--gray-600);
    min-width: 70px;
}
.seg-control {
    display: flex;
    border: 1.5px solid var(--gray-200);
    border-radius: var(--radius);
    overflow: hidden;
    background: #fff;
}
.seg-btn {
    flex: 1;
    padding: .4rem .85rem;
    font-size: .85rem;
    font-weight: 500;
    border: none;
    border-left: 1px solid var(--gray-200);
    background: transparent;
    cursor: pointer;
    color: var(--gray-600);
    transition: background .12s, color .12s;
    white-space: nowrap;
}
.seg-btn:first-child { border-left: none; }
.seg-btn:hover { background: var(--gray-100); color: var(--gray-800); }
.seg-btn.active { background: var(--primary); color: #fff; }

/* ── Kbd hint ─────────────────────────────────────────────── */
kbd {
    display: inline-block;
    padding: .1rem .35rem;
    border: 1px solid var(--gray-300, #d1d5db);
    border-radius: 4px;
    font-size: .75rem;
    font-family: inherit;
    background: var(--gray-100);
    color: var(--gray-600);
    line-height: 1.4;
}
.fc-hint-keys {
    font-size: .78rem;
    color: var(--gray-400);
    margin-top: 1rem;
}

/* ── Mobile ───────────────────────────────────────────────── */
@media (max-width: 600px) {
    main { padding: 1.25rem 1rem; }
    .fc-word, .write-question { font-size: 1.5rem; }
    .stat-num { font-size: 1.4rem; }
    .page-header h1 { font-size: 1.3rem; }
    .seg-btn { padding: .35rem .5rem; font-size: .78rem; }
    .config-row { flex-direction: column; align-items: flex-start; gap: .4rem; }
}