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

:root {
    --black:       #000000;
    --bg:          #080808;
    --surface:     #0f0f0f;
    --surface-2:   #161616;
    --border:      rgba(255, 255, 255, 0.08);
    --border-focus: rgba(255, 255, 255, 0.2);
    --accent:      #4f8ef7;
    --accent-glow: rgba(79, 142, 247, 0.15);
    --text:        #f0f0f0;
    --text-2:      #888888;
    --text-3:      #444444;
    --danger:      #f75555;
    --success:     #3ecf8e;
    --radius-sm:   6px;
    --radius:      10px;
    --radius-lg:   14px;
}

html, body {
    height: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

[hidden] {
    display: none !important;
}

/* ─ Inputs ─────────────────────────────────────────────────────── */

input, textarea {
    display: block;
    width: 100%;
    padding: 0.6rem 0.85rem;
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 0.875rem;
    font-family: inherit;
    outline: none;
    transition: border-color 0.15s, background 0.15s;
    margin-bottom: 0.65rem;
}

input::placeholder, textarea::placeholder {
    color: var(--text-3);
}

input:focus, textarea:focus {
    border-color: var(--border-focus);
    background: #1a1a1a;
}

textarea {
    resize: vertical;
    line-height: 1.5;
}

/* ─ Buttons ─────────────────────────────────────────────────────── */

button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    padding: 0.55rem 1.1rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-family: inherit;
    font-weight: 500;
    cursor: pointer;
    transition: opacity 0.15s, background 0.15s;
    white-space: nowrap;
}

button:hover  { opacity: 0.88; }
button:active { opacity: 0.75; }
button:disabled { opacity: 0.35; cursor: default; }

button.secondary {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-2);
}

button.secondary:hover {
    border-color: var(--border-focus);
    color: var(--text);
    opacity: 1;
}

button.small {
    padding: 0.3rem 0.65rem;
    font-size: 0.75rem;
}

/* ─ Auth panel ──────────────────────────────────────────────────── */

#auth-panel {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 2rem 1rem;
}

.auth-card {
    width: 100%;
    max-width: 380px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 2.25rem 2rem;
}

#auth-panel h1 {
    font-size: 1.2rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    text-align: center;
    margin-bottom: 0.3rem;
}

.tagline {
    font-size: 0.72rem;
    color: var(--text-2);
    text-align: center;
    margin-bottom: 2rem;
    letter-spacing: 0.01em;
}

.auth-divider {
    height: 1px;
    background: var(--border);
    margin: 1.5rem 0;
}

#login-view h2,
#register-view h2 {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-2);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 1rem;
}

#login-view button[id$="-btn"],
#register-view button[id$="-btn"] {
    width: 100%;
    margin-top: 0.25rem;
    padding: 0.65rem;
}

.switch {
    font-size: 0.8rem;
    color: var(--text-2);
    text-align: center;
    margin-top: 1.1rem;
}

.switch a {
    color: var(--accent);
    text-decoration: none;
}

.switch a:hover { text-decoration: underline; }

.error {
    font-size: 0.8rem;
    color: var(--danger);
    text-align: center;
    margin-top: 0.75rem;
    min-height: 1.2em;
}

/* ─ App panel ───────────────────────────────────────────────────── */

#app-panel {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

#app-panel > header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0 1.5rem;
    height: 52px;
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
    background: var(--black);
}

.logo {
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-right: auto;
}

#logged-in-as {
    font-size: 0.78rem;
    color: var(--text-2);
}

#app-panel > main {
    display: grid;
    grid-template-columns: 340px 1fr;
    flex: 1;
    overflow: hidden;
}

/* ─ Compose panel ───────────────────────────────────────────────── */

#compose-section {
    border-right: 1px solid var(--border);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0;
    overflow-y: auto;
    background: var(--surface);
}

#compose-section h2 {
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-2);
    text-transform: uppercase;
    letter-spacing: 0.07em;
    margin-bottom: 1.1rem;
}

#send-btn {
    width: 100%;
    margin-top: 0.25rem;
}

#send-status {
    font-size: 0.75rem;
    color: var(--text-2);
    margin-top: 0.65rem;
    min-height: 1.1em;
}

/* ─ Inbox panel ─────────────────────────────────────────────────── */

#inbox-section {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background: var(--bg);
}

#inbox-section h2 {
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-2);
    text-transform: uppercase;
    letter-spacing: 0.07em;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1.1rem;
    flex-shrink: 0;
}

#inbox-status {
    font-size: 0.75rem;
    color: var(--text-2);
    margin-bottom: 0.5rem;
    flex-shrink: 0;
}

/* ─ Message list ─────────────────────────────────────────────────── */

#message-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    overflow-y: auto;
    flex: 1;
    padding-right: 0.25rem;
}

#message-list::-webkit-scrollbar        { width: 4px; }
#message-list::-webkit-scrollbar-track  { background: transparent; }
#message-list::-webkit-scrollbar-thumb  { background: var(--border); border-radius: 4px; }

#message-list li {
    border-radius: var(--radius);
    padding: 0.85rem 1rem;
    transition: border-color 0.15s;
}

#message-list li.msg-received {
    background: var(--surface);
    border: 1px solid var(--border);
}

#message-list li.msg-received:hover {
    border-color: var(--border-focus);
}

#message-list li.msg-sent {
    background: transparent;
    border: 1px solid var(--border);
    opacity: 0.6;
}

#message-list li.msg-sent:hover {
    opacity: 0.85;
    border-color: var(--border-focus);
}

.msg-body-sent {
    font-size: 0.78rem;
    font-style: italic;
    color: var(--text-2);
}

.msg-meta {
    font-size: 0.72rem;
    color: var(--text-2);
    display: flex;
    justify-content: space-between;
    gap: 0.5rem;
    margin-bottom: 0.45rem;
}

.msg-body {
    font-size: 0.85rem;
    line-height: 1.55;
    word-break: break-word;
    color: var(--text);
}

.msg-body.muted {
    color: var(--text-2);
    font-style: italic;
}

.msg-chain {
    margin-top: 0.5rem;
    font-size: 0.7rem;
    color: var(--text-2);
    display: flex;
    align-items: center;
    gap: 0.35rem;
}

.msg-chain code {
    font-family: 'SF Mono', 'Fira Code', monospace;
    font-size: 0.68rem;
    color: var(--accent);
    background: var(--accent-glow);
    padding: 0.1rem 0.35rem;
    border-radius: 4px;
}

.msg-actions {
    display: flex;
    justify-content: flex-end;
    gap: 0.4rem;
    margin-top: 0.6rem;
}

.msg-delete:hover {
    border-color: #e5484d;
    color: #e5484d;
    opacity: 1;
}

.li-empty {
    color: var(--text-3);
    font-size: 0.82rem;
    text-align: center;
    padding: 2rem 0;
}

/* ─ Responsive ───────────────────────────────────────────────────── */

@media (max-width: 700px) {
    #app-panel > main {
        grid-template-columns: 1fr;
        grid-template-rows: auto 1fr;
        overflow: auto;
    }

    #compose-section {
        border-right: none;
        border-bottom: 1px solid var(--border);
    }

    #inbox-section {
        overflow: visible;
    }

    #message-list {
        overflow: visible;
    }
}