:root {
  --md-primary: #6750A4;
  --md-on-primary: #FFFFFF;
  --md-primary-container: #EADDFF;
  --md-on-primary-container: #21005D;
  --md-surface: #FFFFFF;
  --md-on-surface: #1C1B1F;
  --md-background: #FDFDFD;
  --md-on-background: #1C1B1F;
  --md-outline: #79747E;
  --md-radius: 18px;
  --transition: 0.3s ease;
}
:root.dark {
  --md-primary: #D0BCFF;
  --md-on-primary: #381E72;
  --md-primary-container: #4F378B;
  --md-on-primary-container: #EADDFF;
  --md-surface: #1C1B1F;
  --md-on-surface: #E6E1E5;
  --md-background: #1C1B1F;
  --md-on-background: #E6E1E5;
  --md-outline: #938F99;
}

* { box-sizing: border-box; }
body {
  margin: 0; padding: 0;
  font-family: "Roboto", sans-serif;
  background: var(--md-background);
  color: var(--md-on-background);
  transition: background var(--transition), color var(--transition);
}
a { color: var(--md-primary); text-decoration: none; transition: color var(--transition);}
a:hover { text-decoration: underline; }

/* App Bar */
.app-bar {
  display: flex; justify-content: center; padding: 12px 16px;
  background: var(--md-primary-container);
  color: var(--md-on-primary-container);
  border-bottom: 1px solid var(--md-outline);
  position: sticky; top: 0; z-index: 100;
}
.app-bar-content {
  width: 100%; max-width: 1200px;
  display: flex; justify-content: space-between; align-items: center;
}
.app-title { font-weight: bold; font-size: 1.3rem; }
.top-controls { display: flex; align-items: center; gap: 10px; }

/* Buttons */
.m3-button-filled, .m3-button-tonal {
  padding: 8px 16px; border-radius: var(--md-radius);
  cursor: pointer; position: relative; overflow: hidden; font-weight: 500;
  border: none; transition: background var(--transition);
}
.m3-button-filled {
  background: var(--md-primary); color: var(--md-on-primary);
}
.m3-button-filled:hover { background: rgba(103,80,164,0.85); }
.m3-button-tonal {
  background: var(--md-primary-container); color: var(--md-on-primary-container);
}
.m3-button-tonal:hover { background: rgba(234,221,255,0.85); }

/* Ripple */
.ripple {
  position: absolute; border-radius: 50%; transform: scale(0);
  animation: ripple-effect 0.6s linear;
  background-color: rgba(255,255,255,0.3); pointer-events: none;
}
@keyframes ripple-effect { to { transform: scale(4); opacity: 0; } }

/* Switch */
.m3-switch { position: relative; width: 50px; height: 28px; }
.m3-switch input { opacity: 0; width: 0; height: 0; }
.m3-switch .slider {
  position: absolute; top:0; left:0; right:0; bottom:0;
  background-color: var(--md-outline); border-radius: 34px; transition: var(--transition);
}
.m3-switch .slider:before {
  position: absolute; content: ""; height:22px; width:22px;
  left:3px; bottom:3px; background-color: var(--md-surface);
  border-radius: 50%; transition: var(--transition);
}
.m3-switch input:checked + .slider { background-color: var(--md-primary); }
.m3-switch input:checked + .slider:before { transform: translateX(22px); }

/* Alert Box */
.alert-box {
  max-width: 800px; margin: 20px auto; background: var(--md-primary-container);
  color: var(--md-on-primary-container); border-radius: var(--md-radius);
  padding: 16px; box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* Profile Section */
.profile-section {
  max-width: 900px; margin: 20px auto; background: var(--md-surface);
  padding: 24px; border-radius: var(--md-radius); box-shadow:0 4px 12px rgba(0,0,0,0.1);
}
.profile-section h1 { margin-top:0; font-size:1.8rem; }
.profile-section p { line-height:1.6; margin-bottom:12px; }

/* Popup */
.popup-overlay {
  display:none; position:fixed; top:0; left:0; right:0; bottom:0;
  background: rgba(0,0,0,0.4); justify-content:center; align-items:center; z-index:1000;
}
.popup {
  background: var(--md-surface); color: var(--md-on-surface);
  padding:24px; border-radius: var(--md-radius); width:90%; max-width:420px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.2);
  transform: scale(0.8); opacity:0; transition: var(--transition);
}
.popup.show { transform: scale(1); opacity:1; }
.popup.hide { transform: scale(0.8); opacity:0; }
.close-btn { display:flex; justify-content:flex-end; }
.close-btn button { border:none; background:none; font-size:22px; cursor:pointer; color:var(--md-on-surface); }

/* Footer */
footer {
  margin-top:40px; padding:20px; background:var(--md-primary-container);
  color: var(--md-on-primary-container); text-align:center; border-top:1px solid var(--md-outline);
}
.author-name { font-weight:bold; transition:0.6s; }
.author-name.animate { letter-spacing:4px; }

/* List */
.m3-list { list-style:none; padding:0; margin:0 0 12px 0; }
.m3-list li { padding:6px 0; }

/* Responsive */
@media (max-width:480px) {
  .top-controls { flex-wrap:wrap; gap:6px; }
  .profile-section { padding:16px; }
  .alert-box { padding:12px; }
}