/* =====================================================================
   SIDEBAR  -  the file-explorer navigation, the dark/light switch and the
   mobile burger menu (below 820px the sidebar becomes a sticky top bar).
   ===================================================================== */

:root{--sb:248px}

.side{position:fixed;inset:0 auto 0 0;width:var(--sb);z-index:20;display:flex;flex-direction:column;background:var(--panel);border-right:1px solid var(--line);font:13px/1 var(--mono);padding:env(safe-area-inset-top,0px) 0 env(safe-area-inset-bottom,0px);overflow-y:auto;transition:background-color .35s ease,border-color .35s ease,color .35s ease}
.side .cap{padding:18px 18px 14px;color:var(--dim);font-size:11px;letter-spacing:.14em}
.side .dir{padding:6px 18px 10px;color:var(--strong);display:flex;gap:8px;align-items:center}
.side .dir::before{content:"\25BE";color:var(--dim)}
.side nav{display:flex;flex-direction:column}
.side nav a{display:flex;align-items:center;gap:10px;padding:9px 18px 9px 34px;color:var(--text);border-left:2px solid transparent;transition:background-color var(--motion) var(--ease),color var(--motion) var(--ease),box-shadow var(--motion) var(--ease)}
.side nav a:hover{background:var(--line);color:var(--strong);text-decoration:none}
.side nav a:not(.on):hover{box-shadow:inset 2px 0 0 var(--blue)}
.side nav a.on{background:var(--bg);border-left-color:var(--amber);color:var(--strong)}
.ic2{width:16px;text-align:center;font-weight:700;font-size:11px;flex-shrink:0}
.ext{color:var(--dim)}
.side .foot{margin-top:auto;padding:16px 18px;display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--line);color:var(--dim);font-size:12px}

/* ---- dark/light switch ---- */
.theme{position:relative;width:56px;height:28px;padding:0;border:1px solid var(--line);border-radius:999px;background:var(--panel);color:var(--dim);cursor:pointer;flex-shrink:0;transition:border-color var(--motion) var(--ease),transform var(--motion) var(--ease),box-shadow var(--motion) var(--ease)}
.theme:hover{border-color:var(--dim);transform:translateY(-1px);box-shadow:0 4px 12px rgba(0,0,0,.18)}
.theme:active{transform:scale(.96)}
.theme .ic{position:absolute;top:50%;transform:translateY(-50%);font-size:13px;line-height:1}
.theme .sun{left:7px}.theme .moon{right:7px}
.theme .thumb{position:absolute;top:2px;left:2px;width:22px;height:22px;border-radius:50%;background:var(--amber);transition:transform var(--motion) var(--ease),background var(--motion) var(--ease),box-shadow var(--motion) var(--ease)}
:root:not([data-theme="light"]) .theme .thumb{transform:translateX(28px);background:var(--blue)}
.theme:hover .thumb{box-shadow:0 0 0 3px rgba(122,162,247,.22)}

/* ---- burger button (only visible on mobile) ---- */
.menu{display:none}

@media (max-width:820px){
  :root{--sb:0px}
  .side{position:sticky;inset:auto;top:0;width:100%;flex-direction:row;align-items:center;overflow:visible;border-right:0;border-bottom:1px solid var(--line);min-height:56px}
  .side .cap,.ic2{display:none}
  .side .dir{flex:1;min-width:0;padding:0 16px;font-size:13px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .side nav{position:absolute;top:100%;left:0;right:0;display:none;flex-direction:column;background:var(--panel);border-bottom:1px solid var(--line);box-shadow:0 14px 28px rgba(0,0,0,.28);padding:6px 0;max-height:calc(100svh - 56px);overflow-y:auto}
  .side.open nav{display:flex}
  .side nav a{padding:14px 20px;white-space:nowrap;border-left:2px solid transparent;border-bottom:1px solid var(--line)}
  .side nav a:last-child{border-bottom:0}
  .side nav a.on{background:var(--bg);border-left-color:var(--amber);border-bottom-color:var(--line)}
  .side .foot{margin:0;border:0;padding:0 10px 0 6px;gap:2px;justify-content:flex-end;flex-shrink:0}
  .side .foot>span{display:none}
  .menu{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;width:40px;height:40px;padding:0;border:0;border-radius:6px;background:none;cursor:pointer;flex-shrink:0;transition:background-color var(--motion) var(--ease),transform var(--motion) var(--ease)}
  .menu:hover{background:var(--line)}
  .menu:active{transform:scale(.94)}
  .menu span{display:block;width:18px;height:2px;border-radius:2px;background:var(--text);transition:transform .25s ease,opacity .2s ease}
  .side.open .menu span:nth-child(1){transform:translateY(7px) rotate(45deg)}
  .side.open .menu span:nth-child(2){opacity:0}
  .side.open .menu span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
}

@media (prefers-reduced-motion:reduce){
  .side nav a,.theme,.theme .thumb,.menu,.menu span{transition:none}
  .theme:hover,.theme:active,.menu:active{transform:none}
}