:root{
  --bg-dark: #0f1724;
  --bg-light: #f4f7fb;
  --panel-dark: #0b1220;
  --panel-light: #e6eef6;
  --accent: #13a89e;
  --text-dark: #e6eef6;
  --text-light: #071127;
  --glass-dark: rgba(255,255,255,0.04);
  --glass-light: rgba(0,0,0,0.04);
  --win-dark: linear-gradient(180deg,#0f1724,#071021);
  --win-light: linear-gradient(180deg,#ffffff,#f1f4f8);
  --radius: 10px;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

/* Reset */
*{box-sizing:border-box}
html,body{height:100%;margin:0;background:var(--bg-dark);color:var(--text-dark);-webkit-tap-highlight-color:transparent}
.wallpaper{
  position:fixed;inset:0;
  background:
    radial-gradient(circle at 10% 10%, rgba(19,168,158,0.06), transparent 10%),
    linear-gradient(180deg,#071021 0%, #0b1624 100%);
  transition:background 220ms ease, filter 220ms;
  z-index:0;
}

/* Desktop icons grid */
.desktop{position:fixed;inset:0;padding:16px;display:grid;grid-template-columns:repeat(auto-fill,minmax(92px,1fr));grid-auto-rows:110px;gap:12px;align-content:start;z-index:1}
.icon{
  width:92px;height:92px;display:flex;flex-direction:column;align-items:center;justify-content:center;color:inherit;cursor:pointer;user-select:none;border-radius:10px;padding:6px;background:transparent;
}
.icon span{margin-top:6px;font-size:13px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.icon:active{transform:scale(0.98)}

/* Taskbar */
.taskbar{
  position:fixed;left:0;right:0;bottom:0;height:54px;display:flex;align-items:center;padding:6px 10px;gap:8px;z-index:50;border-top:1px solid rgba(0,0,0,0.25);
  background:linear-gradient(180deg, rgba(0,0,0,0.18), rgba(0,0,0,0.30));
  backdrop-filter: blur(6px);
}
.start-btn{background:transparent;border:1px solid rgba(255,255,255,0.04);color:inherit;padding:8px 12px;border-radius:8px;cursor:pointer}
.taskbar-windows{display:flex;gap:6px;flex:1;align-items:center;overflow:auto;padding-bottom:2px}
.taskbar .task-btn{min-width:110px;padding:8px 10px;border-radius:8px;background:rgba(255,255,255,0.02);color:inherit;border:0;cursor:pointer;white-space:nowrap}
.taskbar-right{display:flex;align-items:center;gap:8px}
.clock-display{padding:6px 10px;border-radius:8px;background:rgba(255,255,255,0.02)}

/* Start menu */
.start-menu{position:fixed;left:10px;bottom:68px;width:280px;background:rgba(10,14,20,0.96);color:var(--text-dark);border-radius:12px;box-shadow:0 12px 30px rgba(2,6,23,0.6);padding:12px;z-index:60}
.start-menu.hidden{display:none}
.start-section{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.start-item{padding:10px;border-radius:8px;cursor:pointer;background:rgba(255,255,255,0.02);text-align:left;border:0}
.start-header{margin-bottom:8px}
.start-footer{text-align:center;margin-top:8px}
.small{font-size:12px;opacity:0.85}

/* Window */
.window{
  position:absolute;min-width:300px;min-height:160px;border-radius:var(--radius);border:1px solid rgba(0,0,0,0.25);box-shadow:0 12px 30px rgba(2,6,23,0.6);overflow:hidden;display:flex;flex-direction:column;z-index:20;
  background:var(--win-dark);
  color:var(--text-dark);
}
.win-title{height:44px;display:flex;align-items:center;gap:8px;padding:0 10px;background:linear-gradient(180deg, rgba(255,255,255,0.02), transparent);cursor:grab;user-select:none}
.win-title .title{flex:1;font-weight:600}
.win-controls{display:flex;gap:6px}
.win-controls button{background:transparent;border:0;color:inherit;padding:6px;border-radius:6px;cursor:pointer}
.window .content{padding:10px;flex:1;overflow:auto}

/* resize handle */
.resize-handle{position:absolute;right:6px;bottom:6px;width:18px;height:18px;border-radius:4px;cursor:se-resize;opacity:0.5}

/* forms and small elements */
textarea.editor{width:100%;height:100%;background:transparent;color:inherit;border:0;resize:none;font-family:monospace;font-size:14px}
.file-list{display:flex;flex-direction:column;gap:6px}
.file-item{padding:8px;background:rgba(255,255,255,0.02);border-radius:8px;display:flex;justify-content:space-between;align-items:center}
.btn{padding:6px 10px;border-radius:8px;border:0;background:var(--accent);color:#022223;cursor:pointer}
.btn.secondary{background:#3a3a3a;color:var(--text-dark)}
.input{padding:8px;border-radius:8px;border:1px solid rgba(255,255,255,0.06);background:transparent;color:inherit}
.terminal{background:#06111a;color:#76f4d9;padding:8px;border-radius:8px;font-family:monospace;font-size:13px}
.term-output{height:220px;overflow:auto;background:rgba(0,0,0,0.06);padding:8px;border-radius:8px;margin-bottom:8px}
.calc-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:6px}
.calc-grid button{padding:12px;border-radius:8px;background:rgba(255,255,255,0.02);color:inherit;border:0;cursor:pointer}
.todo-list{display:flex;flex-direction:column;gap:6px}
.music-list{display:flex;flex-direction:column;gap:6px}

/* light theme overrides (class toggled by JS) */
.light-theme{
  --bg-dark: var(--bg-light);
  --text-dark: var(--text-light);
  --panel-dark: var(--panel-light);
  --glass-dark: var(--glass-light);
  --win-dark: var(--win-light);
  background:var(--bg-light);
}
.light-theme .taskbar{background:linear-gradient(180deg, rgba(255,255,255,0.6), rgba(255,255,255,0.8));border-top:1px solid rgba(0,0,0,0.06)}
.light-theme .start-menu{background:rgba(255,255,255,0.96);color:var(--text-light);box-shadow:0 8px 20px rgba(16,22,40,0.06)}
.light-theme .window{background:var(--win-dark);color:var(--text-light);border:1px solid rgba(0,0,0,0.06)}

/* responsive */
@media (max-width:720px){
  .desktop{grid-template-columns:repeat(auto-fill,minmax(80px,1fr))}
  .taskbar{height:60px}
  .win-title{height:48px}
}