:root {
    --bg: #0b0b0d;
    --panel: #16161a;
    --panel-2: #1e1e24;
    --line: #2a2a31;
    --text: #ececef;
    --muted: #8d8d97;
    --accent: #c0392b;
    --accent-2: #d44636;
    --gold: #f5c46b;
    --radius: 14px;
    --zh: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "Noto Sans SC", sans-serif;
    color-scheme: dark;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
a { color: var(--gold); }
h1 { font-size: 24px; margin: 0; }
h2 { font-size: 18px; margin: 0 0 8px; }
.zh { font-family: var(--zh); }
.muted { color: var(--muted); }
.small { font-size: 13px; }

/* ---------- topbar ---------- */
.topbar {
    position: sticky;
    top: 0;
    z-index: 5;
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 10px 16px;
    padding-top: max(10px, env(safe-area-inset-top));
    background: rgba(11,11,13,.92);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 8px; color: var(--text); text-decoration: none; font-weight: 600; }
.brand-mark {
    width: 32px; height: 32px;
    border-radius: 9px;
    background: var(--accent);
    display: grid; place-items: center;
    font-family: var(--zh);
    font-size: 19px;
}
.topbar nav { display: flex; gap: 4px; margin-left: auto; overflow-x: auto; scrollbar-width: none; }
.topbar nav a { white-space: nowrap; }
.topbar nav a {
    color: var(--muted);
    text-decoration: none;
    padding: 7px 12px;
    border-radius: 9px;
    font-size: 15px;
}
.topbar nav a.active { color: var(--text); background: var(--panel-2); }
@media (max-width: 480px) {
    .brand-text { display: none; }
    .topbar nav a { padding: 7px 9px; font-size: 14px; }
}

.container { max-width: 880px; margin: 0 auto; padding: 20px 16px 100px; }
.page-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 16px; flex-wrap: wrap; }
.panel {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 16px;
    margin-bottom: 16px;
}
.panel-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 4px; }
.panel-head h2 { margin: 0; }

/* ---------- form ---------- */
input:not([type=checkbox]):not([type=range]):not([type=file]), textarea, select {
    width: 100%;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--line);
    border-radius: 10px;
    padding: 10px 12px;
    font: inherit;
}
input:focus, textarea:focus, select:focus { outline: 2px solid var(--accent); outline-offset: -1px; border-color: transparent; }
textarea { resize: vertical; }
label { display: block; }
.lbl, .login-card label, .form-narrow label { display: grid; gap: 6px; color: var(--muted); font-size: 14px; margin-bottom: 12px; }
.check { display: flex !important; align-items: center; gap: 8px; color: var(--text) !important; font-size: 14px; cursor: pointer; }
.check input { width: 18px; height: 18px; accent-color: var(--accent); }
.form-narrow { max-width: 380px; }
.row-btns { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-top: 10px; }

.btn {
    appearance: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    min-height: 42px;
    padding: 0 16px;
    border-radius: 10px;
    border: 1px solid var(--line);
    background: var(--panel-2);
    color: var(--text);
    font: inherit;
    font-size: 15px;
    text-decoration: none;
    cursor: pointer;
    white-space: nowrap;
}
.btn:hover { border-color: #3d3d46; background: #25252c; }
.btn-primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-2); border-color: var(--accent-2); }
.btn-danger-ghost { color: #ff8a7a; }
.btn-danger-ghost:hover { background: rgba(192,57,43,.15); border-color: #7a2a22; }
.btn-sm { min-height: 34px; padding: 0 12px; font-size: 14px; }
.btn-block { width: 100%; }

.icon-btn {
    appearance: none;
    width: 34px; height: 34px;
    border-radius: 8px;
    border: 1px solid var(--line);
    background: var(--panel-2);
    color: var(--text);
    cursor: pointer;
    font-size: 15px;
    flex-shrink: 0;
}
.icon-btn:hover { background: #2a2a32; }
.icon-btn.danger { color: #ff8a7a; }

.alert { padding: 10px 12px; border-radius: 10px; margin-bottom: 12px; font-size: 14px; }
.alert-error { background: rgba(192,57,43,.18); color: #ffb3a8; border: 1px solid #6b261f; }
.alert-ok { background: rgba(46,160,90,.15); color: #9be3b4; border: 1px solid #1f5f38; }

/* ---------- login ---------- */
.login-page { min-height: 100vh; display: grid; place-items: center; padding: 16px; }
.login-card {
    width: 100%;
    max-width: 360px;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 28px 22px;
}
.login-card h1 { text-align: center; font-size: 20px; margin-bottom: 20px; }
.login-mark {
    width: 64px; height: 64px;
    margin: 0 auto 12px;
    border-radius: 16px;
    background: var(--accent);
    display: grid; place-items: center;
    font: 38px var(--zh);
}
.login-card .check { margin: 4px 0 18px; }

/* ---------- danh sách bài ---------- */
.search { margin-bottom: 12px; }
.bai-list { display: grid; gap: 10px; }
.bai-card {
    display: flex;
    align-items: center;
    gap: 12px;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 12px 14px;
}
.bai-main { flex: 1; min-width: 0; color: inherit; text-decoration: none; }
.bai-title { font-weight: 600; font-size: 17px; }
.bai-preview { color: #c9c9d1; font-size: 17px; margin: 2px 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.bai-meta { color: var(--muted); font-size: 13px; }
.bai-actions { display: flex; gap: 6px; flex-shrink: 0; }
@media (max-width: 560px) {
    .bai-card { flex-direction: column; align-items: stretch; }
    .bai-actions .btn { flex: 1; }
}
.empty { text-align: center; padding: 48px 16px; color: var(--muted); }
.empty-mark { font: 64px var(--zh); color: #333; margin-bottom: 8px; }

/* ---------- soạn bài ---------- */
#vanBan { font-size: 18px; }
.cau-list { display: grid; gap: 8px; margin: 12px 0; }
.cau-row {
    display: flex;
    gap: 10px;
    align-items: flex-start;
    background: var(--bg);
    border: 1px solid var(--line);
    border-radius: 12px;
    padding: 10px;
}
.cau-no {
    width: 28px;
    text-align: center;
    color: var(--muted);
    font-size: 13px;
    padding-top: 10px;
    flex-shrink: 0;
    font-variant-numeric: tabular-nums;
}
.cau-body { flex: 1; min-width: 0; display: grid; gap: 6px; }
.cau-body textarea { resize: none; overflow: hidden; }
.cau-han { font-size: 20px; padding: 8px 10px; line-height: 1.4; }
.cau-py-wrap { display: flex; gap: 6px; align-items: flex-start; }
.cau-py { color: var(--gold) !important; font-size: 15px; padding: 6px 10px; }
.cau-py.edited { border-color: #9a7a35 !important; box-shadow: inset 3px 0 0 var(--gold); }
.cau-tools { display: flex; flex-direction: column; gap: 4px; }
@media (max-width: 560px) {
    .cau-row { flex-wrap: wrap; }
    .cau-no { width: auto; padding-top: 0; }
    .cau-body { flex-basis: 100%; order: 2; }
    .cau-tools { flex-direction: row; margin-left: auto; order: 1; }
    .cau-row { row-gap: 6px; }
}

.save-bar {
    position: fixed;
    left: 0; right: 0; bottom: 0;
    display: flex;
    gap: 10px;
    justify-content: center;
    padding: 12px 16px max(12px, env(safe-area-inset-bottom));
    background: rgba(11,11,13,.94);
    border-top: 1px solid var(--line);
    backdrop-filter: blur(8px);
}
.save-bar .btn { flex: 1; max-width: 260px; }

/* ---------- nhạc ---------- */
.gen-list { display: flex; gap: 8px; flex-wrap: wrap; }
.nhac-list { display: grid; gap: 8px; margin-top: 8px; }
.nhac-row {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: var(--bg);
}
.nhac-info { flex: 1; min-width: 0; }
.nhac-ten { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.icon-btn.play { width: 40px; height: 40px; border-radius: 50%; }
@media (max-width: 480px) {
    .nhac-row { flex-wrap: wrap; }
    .nhac-info { flex-basis: calc(100% - 60px); }
    .nhac-row .btn { flex: 1; }
}
#tienTrinh { margin: 8px 0; }

/* ---------- người dùng ---------- */
.user-form { display: grid; gap: 4px; max-width: 460px; }
.user-form .lbl { margin-bottom: 8px; }
.user-form .check { margin-bottom: 10px; }
.user-list { display: grid; gap: 8px; margin-top: 8px; }
.user-row { border: 1px solid var(--line); border-radius: 12px; background: var(--bg); }
.user-row summary {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px;
    cursor: pointer;
    list-style: none;
}
.user-row summary::-webkit-details-marker { display: none; }
.user-row[open] summary { border-bottom: 1px solid var(--line); }
.user-row[open] summary .btn { visibility: hidden; }
.user-row > form { padding: 12px 12px 0; }
.user-row > .user-del { padding: 0 12px 12px; margin-top: 8px; }
.user-row > form.user-form:last-child { padding-bottom: 12px; }
.user-main { flex: 1; min-width: 0; }
.user-name { font-weight: 600; display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.badge { font-size: 11px; font-weight: 600; padding: 2px 7px; border-radius: 999px; background: rgba(192,57,43,.2); color: #ff9d90; }
.badge-share { background: rgba(80,150,255,.16); color: #9cc3ff; vertical-align: middle; margin-left: 4px; }
.badge-me {background: rgba(245,196,107,.18); color: var(--gold); }

.toast {
    position: fixed;
    left: 50%;
    bottom: 90px;
    transform: translateX(-50%);
    background: #2b2b33;
    color: #fff;
    padding: 10px 16px;
    border-radius: 10px;
    font-size: 14px;
    z-index: 20;
    box-shadow: 0 6px 24px rgba(0,0,0,.4);
    max-width: calc(100% - 32px);
}
.toast-error { background: #a93226; }