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

:root {
  --bg: #ede6d6;
  --paper: #e4d9c4;
  --ink: #261810;
  --ink-mid: #4a3018;
  --ink-light: #5c3d20;
  --ink-dim: #7a6050;
  --terracotta: #b05840;
  --sage: #6e8050;
  --blue: #5c7888;
  --gold: #a8882e;
  --font-mono: 'Courier Prime', 'Courier New', Courier, monospace;
  --font-serif: 'EB Garamond', Georgia, serif;
}

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

/* subtle paper grain */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.04'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 900;
  opacity: 0.5;
}

/* Layout */
#app {
  display: flex;
  flex-direction: column;
  height: 100dvh;
  max-width: 760px;
  margin: 0 auto;
  padding: 0 1.5rem;
  position: relative;
  z-index: 1;
}

/* Header */
#header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 1.5rem 0 1rem;
  border-bottom: 1px solid var(--ink-dim);
  flex-shrink: 0;
}

#title-block {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.title-text {
  font-family: var(--font-serif);
  font-size: 3rem;
  font-weight: 400;
  font-style: italic;
  letter-spacing: 0.18em;
  color: var(--ink);
  text-transform: lowercase;
}

.subtitle-text {
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.22em;
  color: var(--ink-light);
  text-transform: uppercase;
}

.btn-ghost {
  background: none;
  border: none;
  border-bottom: 1px solid var(--ink-dim);
  color: var(--ink-light);
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.15em;
  padding: 0.2rem 0;
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s;
  text-transform: uppercase;
}

.btn-ghost:hover {
  color: var(--ink-mid);
  border-color: var(--ink-mid);
}

#header-btns {
  display: flex;
  gap: 1.25rem;
  align-items: baseline;
}

/* How this works overlay */
#how-overlay {
  position: fixed;
  inset: 0;
  background: rgba(237, 230, 214, 0.97);
  z-index: 500;
  display: flex;
  overflow: hidden;
}

#how-overlay.hidden {
  display: none;
}

#how-panel {
  width: 100%;
  max-width: 620px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

#how-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  border-bottom: 1px solid var(--ink-dim);
  padding-bottom: 0.75rem;
}

#how-header h2 {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 400;
  font-style: italic;
  letter-spacing: 0.2em;
  color: var(--ink);
  text-transform: lowercase;
}

#close-how {
  background: none;
  border: none;
  color: var(--ink-light);
  font-family: var(--font-mono);
  font-size: 1rem;
  cursor: pointer;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0;
}

#close-how:hover { color: var(--ink); }

#how-body {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

#how-body p {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ink-mid);
}

#how-body p em {
  color: var(--ink);
}

.how-credit a {
  color: var(--ink-mid);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.how-credit a:hover {
  color: var(--ink);
}

.how-credit {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: var(--ink-dim);
  border-top: 1px solid var(--ink-dim);
  padding-top: 1rem;
  margin-top: 0.5rem;
}

/* Ocean visualization */
#ocean-vis {
  height: 80px;
  flex-shrink: 0;
  overflow: hidden;
  position: relative;
}

#wave-canvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* Conversation */
#conversation-wrap {
  flex: 1;
  overflow-y: auto;
  padding: 1.5rem 0 0.5rem;
  scrollbar-width: thin;
  scrollbar-color: var(--ink-dim) transparent;
}

#conversation-wrap::-webkit-scrollbar {
  width: 3px;
}

#conversation-wrap::-webkit-scrollbar-thumb {
  background: var(--ink-dim);
}

#messages {
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

/* Message blocks */
.message-block {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

.msg-label {
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.28em;
  color: var(--ink-dim);
  text-transform: uppercase;
}

.msg-human-text {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--ink-mid);
}

.msg-morse {
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 2.1;
  color: var(--ink-dim);
  letter-spacing: 0.06em;
  word-break: break-all;
  min-height: 1.4em;
}

.msg-ocean-morse {
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 2.1;
  color: var(--ink-light);
  letter-spacing: 0.06em;
  word-break: break-all;
  min-height: 1.4em;
}

.msg-ocean-text {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ink);
  font-style: italic;
  opacity: 0;
  transition: opacity 1.2s ease-in;
}

.msg-ocean-text.revealed {
  opacity: 1;
}

/* Status */
#status-wrap {
  flex-shrink: 0;
  border-top: 1px solid var(--paper);
  padding-top: 0.45rem;
  min-height: 1.8rem;
}

#status-text {
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.2em;
  color: var(--ink-dim);
  text-transform: uppercase;
}

#status-text.active {
  color: var(--terracotta);
}

/* Input */
#input-wrap {
  flex-shrink: 0;
  padding: 0.4rem 0 1.5rem;
}

#input-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

#cursor-symbol {
  color: var(--ink-dim);
  font-family: var(--font-serif);
  font-size: 1.1rem;
  flex-shrink: 0;
  font-style: italic;
}

#user-input {
  flex: 1;
  background: none;
  border: none;
  border-bottom: 1px solid var(--ink-dim);
  color: var(--ink);
  font-family: var(--font-serif);
  font-size: 1rem;
  padding: 0.35rem 0.15rem;
  outline: none;
  caret-color: var(--terracotta);
  min-width: 0;
}

#user-input::placeholder {
  color: var(--ink-dim);
  font-style: italic;
}

#user-input:focus {
  border-bottom-color: var(--ink-mid);
}

#user-input:disabled {
  opacity: 0.35;
}

#send-btn {
  background: none;
  border: none;
  border-bottom: 1px solid var(--ink-dim);
  color: var(--ink-light);
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.18em;
  padding: 0.35rem 0;
  cursor: pointer;
  flex-shrink: 0;
  transition: color 0.2s, border-color 0.2s;
  text-transform: uppercase;
}

#send-btn:hover:not(:disabled) {
  color: var(--ink-mid);
  border-color: var(--ink-mid);
}

#send-btn:disabled {
  opacity: 0.22;
  cursor: not-allowed;
}

/* Archive overlay */
#archive-overlay {
  position: fixed;
  inset: 0;
  background: rgba(237, 230, 214, 0.97);
  z-index: 500;
  display: flex;
  overflow: hidden;
}

#archive-overlay.hidden {
  display: none;
}

#archive-panel {
  width: 100%;
  max-width: 760px;
  margin: 0 auto;
  padding: 1.5rem 1.5rem 2rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

#archive-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  border-bottom: 1px solid var(--ink-dim);
  padding-bottom: 0.75rem;
  flex-shrink: 0;
}

#archive-header h2 {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 400;
  font-style: italic;
  letter-spacing: 0.2em;
  color: var(--ink);
  text-transform: lowercase;
}

#close-archive {
  background: none;
  border: none;
  color: var(--ink-light);
  font-family: var(--font-mono);
  font-size: 1rem;
  cursor: pointer;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0;
}

#close-archive:hover {
  color: var(--ink);
}

#archive-count {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--ink-dim);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  flex-shrink: 0;
}

#archive-entries {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.archive-entry {
  border-left: 1px solid var(--ink-dim);
  padding: 0.4rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

.entry-date {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--ink-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.entry-human {
  font-family: var(--font-serif);
  font-size: 1rem;
  color: var(--ink-mid);
  line-height: 1.55;
}

.entry-human::before {
  content: '— ';
  color: var(--ink-dim);
}

.entry-ocean {
  font-family: var(--font-serif);
  font-size: 1rem;
  color: var(--ink);
  font-style: italic;
  line-height: 1.7;
}

/* Intro */
#intro-msg {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--ink-dim);
  letter-spacing: 0.2em;
  text-align: center;
  margin-top: 3.5rem;
  text-transform: uppercase;
}

/* Animations */
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.pulsing {
  animation: pulse 2s ease-in-out infinite;
}

/* Responsive */
@media (max-width: 540px) {
  .title-text { font-size: 1.2rem; }
  #ocean-vis { height: 60px; }
  #user-input { font-size: 1rem; }
  #app { padding: 0 1rem; }
}