/* ============================================================
   飞歌音乐 · 整站应用壳布局（左侧边栏 + 右侧主内容区）
   所有页面共用：static/css/app.css + static/js/app-shell.js
   ============================================================ */

:root {
    --sb-width: 256px;
    --sb-bg: rgba(13, 18, 33, 0.94);
    --sb-border: rgba(255, 255, 255, 0.07);
    --sb-accent: #8b5cf6;
    --sb-accent-soft: rgba(139, 92, 246, 0.16);
    --sb-text: #e5e7eb;
    --sb-text-muted: #8b93a7;
    --sb-hover: rgba(255, 255, 255, 0.05);
    --sb-active-text: #ffffff;
}

/* ---------- 整体壳 ---------- */
.app-shell { display: flex; min-height: 100vh; width: 100%; }
.app-main {
    flex: 1 1 auto;
    min-width: 0;
    margin-left: var(--sb-width);
    position: relative;
    z-index: 1;
    transition: margin-left 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- 侧边栏 ---------- */
.sidebar {
    position: fixed;
    top: 0; left: 0; bottom: 0;
    width: var(--sb-width);
    display: flex;
    flex-direction: column;
    background: var(--sb-bg);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-right: 1px solid var(--sb-border);
    z-index: 120;
    transition: width 0.28s cubic-bezier(0.4, 0, 0.2, 1),
                transform 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 品牌区 */
.sb-brand {
    display: flex; align-items: center; gap: 12px;
    padding: 20px 18px 18px;
    border-bottom: 1px solid var(--sb-border);
}
.sb-logo {
    width: 40px; height: 40px; flex: none;
    border-radius: 12px;
    display: flex; align-items: center; justify-content: center;
    font-size: 20px;
    background: linear-gradient(135deg, #8b5cf6, #06b6d4);
    box-shadow: 0 4px 16px rgba(139, 92, 246, 0.35);
}
.sb-brand-name { font-size: 16px; font-weight: 700; color: var(--sb-text); letter-spacing: 0.2px; }
.sb-brand-sub { font-size: 11px; color: var(--sb-text-muted); margin-top: 1px; }

/* 导航区 */
.sb-nav {
    flex: 1 1 auto;
    overflow-y: auto;
    padding: 12px 12px 20px;
}
.sb-nav::-webkit-scrollbar { width: 5px; }
.sb-nav::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.12); border-radius: 4px; }
.sb-nav::-webkit-scrollbar-track { background: transparent; }

.sb-group {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    color: var(--sb-text-muted);
    padding: 16px 10px 7px;
}
.sb-group:first-child { padding-top: 8px; }

.sb-item {
    display: flex; align-items: center; gap: 11px;
    padding: 8px 11px;
    margin: 2px 0;
    border-radius: 10px;
    text-decoration: none;
    color: var(--sb-text);
    font-size: 14px;
    line-height: 1.4;
    position: relative;
    transition: background 0.2s ease, color 0.2s ease;
}
.sb-item:hover { background: var(--sb-hover); color: #ffffff; }
.sb-item .sb-icon {
    width: 22px; flex: none;
    font-size: 15px;
    text-align: center;
    filter: saturate(0.85);
}
.sb-item .sb-label { flex: 1 1 auto; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* 当前页高亮 */
.sb-item.active {
    background: var(--sb-accent-soft);
    color: var(--sb-active-text);
    box-shadow: inset 0 0 0 1px rgba(139, 92, 246, 0.28);
}
.sb-item.active::before {
    content: '';
    position: absolute; left: 0; top: 20%; bottom: 20%;
    width: 3px; border-radius: 3px;
    background: linear-gradient(180deg, #8b5cf6, #06b6d4);
}
.sb-item.active .sb-icon { filter: none; }

/* 底部 */
.sb-footer {
    padding: 14px 18px;
    border-top: 1px solid var(--sb-border);
    font-size: 11px;
    color: var(--sb-text-muted);
    text-align: center;
}

/* 桌面端折叠/展开按钮 */
.sb-collapse-btn {
    display: flex; align-items: center; justify-content: center; gap: 8px;
    margin: 6px 12px 12px;
    padding: 9px 0;
    border: 1px solid var(--sb-border);
    border-radius: 10px;
    background: transparent;
    color: var(--sb-text-muted);
    font-size: 11px;
    cursor: pointer;
    transition: background 0.2s ease, color 0.2s ease;
    flex-shrink: 0;
}
.sb-collapse-btn:hover { background: var(--sb-hover); color: #ffffff; }
.sb-collapse-btn svg {
    width: 15px; height: 15px;
    stroke: currentColor;
    transition: transform 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}
.sb-collapse-btn .sb-collapse-text { transition: opacity 0.2s ease; }

/* ---------- 桌面端折叠态：侧边栏收成 64px 图标条 ---------- */
body.sb-collapsed { --sb-width: 64px; }

body.sb-collapsed .sb-brand {
    justify-content: center;
    padding: 20px 6px 18px;
    gap: 0;
}
body.sb-collapsed .sb-brand-text { display: none; }

body.sb-collapsed .sb-nav { padding: 12px 8px 20px; }
body.sb-collapsed .sb-group {
    font-size: 0;
    padding: 14px 0 4px;
    letter-spacing: 0;
}
body.sb-collapsed .sb-group::before {
    content: '';
    display: block;
    width: 26px; height: 1px;
    margin: 0 auto;
    background: var(--sb-border);
}

body.sb-collapsed .sb-item {
    justify-content: center;
    padding: 10px 0;
    gap: 0;
}
body.sb-collapsed .sb-item .sb-icon { font-size: 17px; }
body.sb-collapsed .sb-item .sb-label { display: none; }

body.sb-collapsed .sb-footer { font-size: 0; padding: 10px 0; }

body.sb-collapsed .sb-collapse-btn { margin: 6px 8px 10px; }
body.sb-collapsed .sb-collapse-btn svg { transform: rotate(180deg); }
body.sb-collapsed .sb-collapse-btn .sb-collapse-text { opacity: 0; width: 0; overflow: hidden; }

/* ---------- 移动端：抽屉式侧边栏 ---------- */
.sb-toggle {
    display: none;
    position: fixed;
    top: 14px; left: 14px;
    width: 40px; height: 40px;
    align-items: center; justify-content: center;
    border: 1px solid var(--sb-border);
    border-radius: 10px;
    background: rgba(13, 18, 33, 0.9);
    backdrop-filter: blur(10px);
    cursor: pointer;
    z-index: 130;
}
.sb-toggle svg { width: 18px; height: 18px; stroke: #e5e7eb; }

.sb-backdrop {
    display: none;
    position: fixed; inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 110;
}

@media (max-width: 900px) {
    /* 移动端忽略桌面折叠态，抽屉按全宽显示 */
    body.sb-collapsed { --sb-width: 256px; }
    body.sb-collapsed .sb-brand { justify-content: flex-start; padding: 20px 18px 18px; gap: 12px; }
    body.sb-collapsed .sb-brand-text,
    body.sb-collapsed .sb-group::before { display: block; }
    body.sb-collapsed .sb-group { font-size: 11px; padding: 16px 10px 7px; letter-spacing: 1.2px; }
    body.sb-collapsed .sb-item { justify-content: flex-start; padding: 8px 11px; gap: 11px; }
    body.sb-collapsed .sb-item .sb-icon { font-size: 15px; }
    body.sb-collapsed .sb-item .sb-label { display: block; }
    body.sb-collapsed .sb-footer { font-size: 11px; padding: 14px 18px; }

    .app-main { margin-left: 0; }
    .sidebar { transform: translateX(-100%); box-shadow: none; }
    .sb-toggle { display: flex; }
    .sb-collapse-btn { display: none; }
    body.sidebar-open .sidebar { transform: translateX(0); box-shadow: 0 0 40px rgba(0,0,0,0.6); }
    body.sidebar-open .sb-backdrop { display: block; }
}

/* ---------- 通用页面头（右侧主区域共用） ---------- */
.page-head { margin-bottom: 34px; }
.page-title {
    font-size: 30px; font-weight: 800; letter-spacing: -0.5px;
    color: var(--text-primary, #f0f0f5);
    margin: 0 0 10px;
}
.page-sub {
    font-size: 14px;
    color: var(--text-secondary, #9ca3af);
    margin: 0;
    max-width: 640px;
    line-height: 1.7;
}
.section-title {
    font-size: 15px; font-weight: 700;
    color: var(--text-secondary, #9ca3af);
    letter-spacing: 1px;
    margin: 0 0 16px;
    display: flex; align-items: center; gap: 10px;
}
.section-title::after {
    content: '';
    flex: 1; height: 1px;
    background: linear-gradient(90deg, rgba(255,255,255,0.12), transparent);
}