:root {
  --bg: #f2efe8;
  --panel: rgba(255, 255, 255, 0.86);
  --line: rgba(22, 31, 45, 0.08);
  --text: #18202b;
  --muted: #6e7784;
  --accent: #bb4d00;
  --accent-dark: #8d3700;
  --inbound: #fff7e8;
  --outbound: #eaf4ff;
  --internal: #f2ecff;
  --shadow: 0 20px 60px rgba(23, 26, 31, 0.12);
  --radius: 24px;
  font-family: "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(255, 201, 109, 0.55), transparent 30%),
    radial-gradient(circle at bottom right, rgba(85, 144, 255, 0.2), transparent 35%),
    var(--bg);
}

.shell {
  display: grid;
  grid-template-columns: 360px 1fr;
  min-height: 100vh;
  gap: 20px;
  padding: 20px;
}

.sidebar,
.conversation-panel,
.empty-state {
  background: var(--panel);
  backdrop-filter: blur(18px);
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.sidebar {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.brand,
.toolbar {
  padding: 20px;
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

h1,
h2,
.panel-subject {
  margin: 0;
  font-family: Georgia, serif;
  font-weight: 700;
}

.toolbar {
  display: grid;
  gap: 10px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

input,
textarea,
button {
  font: inherit;
}

input,
textarea {
  width: 100%;
  padding: 14px 16px;
  border-radius: 16px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.8);
}

textarea {
  resize: vertical;
}

.conversation-list {
  flex: 1;
  overflow: auto;
  padding: 12px;
}

.conversation-card {
  width: 100%;
  text-align: left;
  border: 1px solid transparent;
  background: transparent;
  border-radius: 18px;
  padding: 14px;
  display: grid;
  gap: 8px;
  transition: 0.2s ease;
  cursor: pointer;
}

.conversation-card:hover,
.conversation-card.active {
  background: rgba(255, 255, 255, 0.82);
  border-color: var(--line);
}

.conversation-card-top,
.conversation-card-bottom {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.conversation-card-subject {
  font-weight: 600;
}

.conversation-card-preview,
.conversation-card-meta,
.panel-meta,
.composer-hint {
  color: var(--muted);
  font-size: 14px;
}

.content {
  min-width: 0;
}

.empty-state,
.conversation-panel {
  min-height: calc(100vh - 40px);
}

.empty-state {
  display: grid;
  place-content: center;
  padding: 32px;
  text-align: center;
}

.conversation-panel {
  display: grid;
  grid-template-rows: auto 1fr auto auto;
  overflow: hidden;
}

.panel-header,
.composer,
.composer-tabs {
  padding: 20px 24px;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px solid var(--line);
}

.panel-actions,
.composer-footer {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.message-list {
  overflow: auto;
  padding: 24px;
  display: grid;
  gap: 14px;
}

.message {
  max-width: 75%;
  padding: 16px 18px;
  border-radius: 20px;
  box-shadow: 0 10px 30px rgba(26, 32, 41, 0.06);
}

.message.inbound {
  background: var(--inbound);
  justify-self: start;
}

.message.outbound {
  background: var(--outbound);
  justify-self: end;
}

.message.internal {
  background: var(--internal);
  justify-self: end;
}

.message-meta {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 8px;
}

.composer-tabs {
  display: flex;
  gap: 8px;
  border-top: 1px solid var(--line);
}

.tab-button,
.ghost-button,
.primary-button {
  border: none;
  border-radius: 999px;
  padding: 11px 16px;
  cursor: pointer;
}

.tab-button,
.ghost-button {
  background: rgba(24, 32, 43, 0.06);
  color: var(--text);
}

.tab-button.active,
.primary-button {
  background: var(--accent);
  color: #fff;
}

.primary-button:hover {
  background: var(--accent-dark);
}

.composer {
  display: grid;
  gap: 12px;
  border-top: 1px solid var(--line);
}

.composer-footer {
  justify-content: space-between;
}

.hidden {
  display: none;
}

@media (max-width: 980px) {
  .shell {
    grid-template-columns: 1fr;
    padding: 12px;
  }

  .sidebar,
  .empty-state,
  .conversation-panel {
    min-height: auto;
  }

  .message {
    max-width: 100%;
  }
}