:root {
    --bg: #14213d;
    --panel: #1f2f55;
    --text: #f4f4f8;
    --muted: #a9b4d0;
    --accent: #fca311;
    --front: #3a86ff;
    --back: #2a9d8f;
    --back-face: #52618f;
    --ok: #3ddc84;
}
* { box-sizing: border-box; }
body {
    margin: 0;
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    font-family: "Segoe UI", system-ui, "Noto Sans SC", "Microsoft YaHei", "PingFang SC", sans-serif;
}
.hidden { display: none !important; }
.screen { max-width: 960px; margin: 0 auto; padding: 16px; }
h1 { text-align: center; margin: 24px 0; }
.panel {
    background: var(--panel);
    border-radius: 14px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 14px;
    max-width: 520px;
    margin: 0 auto;
}
label { display: flex; flex-direction: column; gap: 6px; color: var(--muted); font-size: 14px; }
select, button {
    font: inherit;
    padding: 10px 12px;
    border-radius: 8px;
    border: 1px solid #3a4a78;
    background: #14213d;
    color: var(--text);
}
button { cursor: pointer; }
button.primary { background: var(--accent); color: #14213d; border: 0; font-weight: 700; }
.hint { color: var(--muted); text-align: center; margin: 0; min-height: 1.2em; }
.admin-link { display: block; text-align: center; margin-top: 18px; color: var(--muted); font-size: 13px; }
.bar {
    display: flex;
    flex-wrap: wrap;
    gap: 10px 18px;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 14px;
}
#tablero {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(104px, 1fr));
    gap: 10px;
}
.card {
    perspective: 700px;
    aspect-ratio: 3 / 4;
    cursor: pointer;
    user-select: none;
}
.card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.45s;
    transform-style: preserve-3d;
}
.card.open .card-inner, .card.done .card-inner { transform: rotateY(180deg); }
.face {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 6px;
    text-align: center;
    overflow: hidden;
}
.face.cover {
    background: repeating-linear-gradient(45deg, #2b3d6b, #2b3d6b 10px, #243459 10px, #243459 20px);
    border: 2px solid #3a4a78;
    font-size: 34px;
    color: #4d6097;
}
.face.content { transform: rotateY(180deg); font-size: 14px; }
.card.front .face.content { background: var(--front); }
.card.meaning .face.content { background: var(--back); }
.card.done .face.content { box-shadow: 0 0 0 3px var(--ok) inset; }
.hanzi { font-size: 38px; line-height: 1.1; font-weight: 600; }
.hanzi.long { font-size: 28px; }
.pinyin { font-size: 17px; color: #ffe8b0; }
.meaning-text { font-size: 17px; line-height: 1.25; overflow-wrap: anywhere; }
@media (max-width: 480px) {
    #tablero { grid-template-columns: repeat(3, 1fr); }
    .hanzi { font-size: 30px; }
}
.range { display: flex; gap: 12px; }
.range label { flex: 1; }
input[type=number] {
    font: inherit;
    padding: 10px 12px;
    border-radius: 8px;
    border: 1px solid #3a4a78;
    background: #14213d;
    color: var(--text);
    width: 100%;
}
label.check { flex-direction: row; align-items: center; gap: 8px; color: var(--text); }