/* ═══════════════════════════════════════════════════════════
   Base Styles - Layout & Structural
   No colors here (use variables). No component specifics.
   ═══════════════════════════════════════════════════════════ */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  background: var(--color-bg);
  color: var(--color-text);
  overflow: hidden;
}

body {
  background:
    radial-gradient(circle at 18% 12%, color-mix(in srgb, var(--color-accent) 20%, transparent), transparent 34%),
    radial-gradient(circle at 88% 0%, rgba(255, 255, 255, 0.08), transparent 28%),
    linear-gradient(145deg, var(--color-bg), color-mix(in srgb, var(--color-bg) 76%, #000 24%));
}

body::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    linear-gradient(rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.018) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(circle at 50% 40%, black, transparent 72%);
}

#matrix-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  opacity: 0.42;
  pointer-events: none;
  mix-blend-mode: screen;
}

body.matrix-disabled #matrix-bg {
  display: none;
}

/* ── App Shell ── */
#app {
  display: flex;
  height: 100vh;
  width: 100vw;
  position: relative;
  z-index: 1;
  padding: 14px;
  gap: 14px;
}

/* ── Sidebar ── */
#sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  max-width: var(--sidebar-width);
  height: 100%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  backdrop-filter: var(--blur-panel);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-header {
  height: var(--header-height);
  padding: 0 var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}

.sidebar-header h1 {
  font-size: 18px;
  color: var(--color-accent);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.sidebar-scroll {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-sm) 0;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
}

.sidebar-footer {
  padding: var(--space-md);
  border-top: 1px solid var(--color-border);
  flex-shrink: 0;
}

/* ── Main Content ── */
#main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  overflow: hidden;
  background: color-mix(in srgb, var(--color-surface) 78%, transparent);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  backdrop-filter: var(--blur-panel);
}

/* ── Top Header ── */
#top-header {
  height: var(--header-height);
  background: linear-gradient(180deg, color-mix(in srgb, var(--color-surface-raised) 72%, transparent), transparent);
  border-bottom: 1px solid var(--color-border);
  padding: 0 var(--space-xl);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
  gap: var(--space-md);
}

.header-left {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  min-width: 0;
}

.header-right {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex-shrink: 0;
}

.instance-name {
  font-size: 17px;
  font-weight: 700;
  color: var(--color-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.instance-meta {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* ── Chat Area ── */
#chat-container {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 28px clamp(14px, 3vw, 42px);
  display: flex;
  flex-direction: column;
  gap: 12px;
  scroll-behavior: smooth;
}

/* ── Input Area ── */
#input-area {
  background: color-mix(in srgb, var(--color-surface-solid) 80%, transparent);
  border-top: 1px solid var(--color-border);
  padding: 14px clamp(14px, 3vw, 28px);
  display: flex;
  gap: 10px;
  flex-shrink: 0;
  align-items: flex-end;
}

/* ── Buttons ── */
.btn {
  background: linear-gradient(135deg, var(--color-accent-bg), color-mix(in srgb, var(--color-accent) 16%, transparent));
  border: 1px solid color-mix(in srgb, var(--color-accent) 38%, transparent);
  color: var(--color-accent);
  padding: 10px 18px;
  border-radius: var(--radius-xl);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--font-size-base);
  transition: transform var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
}

.btn:hover {
  transform: translateY(-1px);
  border-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent-bg) 72%, var(--color-accent) 28%);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-icon {
  background: color-mix(in srgb, var(--color-surface-raised) 68%, transparent);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  cursor: pointer;
  font-size: var(--font-size-lg);
  min-width: 38px;
  min-height: 38px;
  padding: var(--space-sm);
  border-radius: var(--radius-xl);
  transition: color var(--transition-fast), background var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-icon:hover {
  color: var(--color-accent);
  background: var(--color-accent-bg);
  border-color: color-mix(in srgb, var(--color-accent) 40%, transparent);
}

/* ── Inputs ── */
input[type="text"],
input[type="email"],
textarea,
select {
  background: var(--color-surface-raised);
  border: 1px solid var(--color-border);
  color: var(--color-text);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-lg);
  font-family: inherit;
  font-size: var(--font-size-base);
  outline: none;
  transition: border-color var(--transition-fast);
}

input:focus,
textarea:focus,
select:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 18%, transparent);
}

select {
  cursor: pointer;
}

/* ── Scrollbar ── */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: var(--radius-xl);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-dim);
}

/* ── Mobile Sidebar Toggle ── */
#sidebar-toggle {
  display: none;
}

/* ── Responsive (Mobile) ── */
@media (max-width: 768px) {
  #app,
  #main {
    height: 100dvh;
  }

  #app {
    padding: 0;
    gap: 0;
  }

  #main {
    border-radius: 0;
    border: none;
  }

  #sidebar-toggle {
    display: flex;
  }

  #sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    z-index: 200;
    width: min(86vw, var(--sidebar-width));
    min-width: 0;
    max-width: min(86vw, var(--sidebar-width));
    transform: translateX(-100%);
    transition: transform var(--transition-base);
    border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
    box-shadow: 4px 0 40px rgba(0,0,0,0.45);
  }

  body.sidebar-open #sidebar {
    transform: translateX(0);
  }

  /* Overlay backdrop when sidebar is open.
     Keep this inside #app's stacking context so the sidebar remains touchable. */
  body.sidebar-open #app::before {
    content: '';
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 150;
  }

  #top-header {
    padding: 0 10px;
    gap: var(--space-sm);
    min-width: 0;
  }

  .header-left {
    flex: 1;
    min-width: 0;
  }

  .header-right {
    gap: var(--space-sm);
    min-width: 0;
  }

  .header-right #rename-btn {
    display: none;
  }

  .header-right .compact-header-toggle {
    display: flex;
    flex-shrink: 0;
  }

  .header-right .compact-header-toggle .toggle-track {
    width: 38px;
    height: 22px;
  }

  .header-right .compact-header-toggle .toggle-thumb {
    width: 16px;
    height: 16px;
  }

  .header-right .compact-header-toggle input:checked + .toggle-track .toggle-thumb {
    transform: translateX(16px);
  }

  .context-bar {
    width: 80px;
  }

  #chat-container {
    padding: 16px 10px;
  }

  .message {
    max-width: 95%;
  }

  #input-area {
    padding: 10px;
    gap: var(--space-sm);
  }

  #message-input {
    min-width: 0;
  }

  #scroll-indicator {
    bottom: 80px;
    right: 16px;
  }
}

@media (max-width: 480px) {
  #top-header {
    padding: 8px;
  }

  .instance-meta,
  .context-bar {
    display: none;
  }

  .status-badge {
    display: none;
  }

  .checkpoint-indicator {
    display: none;
  }

  #input-area {
    display: grid;
    grid-template-columns: auto 1fr;
    align-items: stretch;
  }

  #message-input {
    grid-column: 1 / -1;
    width: 100%;
    order: 1;
  }

  #upload-btn {
    min-height: 44px;
    order: 2;
  }

  #send-btn {
    width: 100%;
    min-height: 44px;
    order: 3;
    justify-content: center;
  }
}

/* ── Utility ── */
.hidden { display: none !important; }
.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.truncate {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}