html, body {
    width: 100%;
    height: 100%;
    height: var(--app-height, 100dvh);
    overflow: hidden;
    -webkit-text-size-adjust: 100%;
}

body {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* ---- Layout ---- */
.layout {
    display: grid;
    grid-template-columns: 280px minmax(0, 1fr);
    grid-template-rows: auto minmax(0, 1fr);
    width: 100%;
    flex: 1;
    min-height: 0;
    overflow: hidden;
}

/* ---- Topbar ---- */
.topbar {
    grid-column: 1 / -1;
    grid-row: 1;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 1.5rem;
    background: transparent; 
    border-bottom: none; 
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    min-height: auto;
    min-width: 0;
}


.menu-button {
    display: none;
    background: transparent;
    color: var(--ink);
    border: 1px solid var(--border);
    border-radius: 2px;
    padding: 0.4rem 0.65rem;
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    cursor: pointer;
    transition: border-color 0.2s, color 0.2s;
}
.menu-button:hover { border-color: var(--ink-muted); }

.drawer-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.45);
    z-index: 40;
    backdrop-filter: blur(2px);
}

/* ---- Sidebar ---- */
.sidebar {
    grid-column: 1;
    grid-row: 2;
    border-right: 1px solid var(--border);
    background: var(--bg-panel);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-width: 0;
    transition: background 0.3s ease;
}

.sidebar-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    justify-content: space-between;
}

.sidebar-title {
    font-size: 0.65rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.2em;
    color: var(--ink-dim);
}

.close-sidebar {
    display: none;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--ink-muted);
    border-radius: 2px;
    padding: 0.35rem 0.6rem;
    cursor: pointer;
    font-size: 0.68rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}
.close-sidebar:hover { color: var(--ink); border-color: var(--ink-muted); }

#session-list {
    flex: 1;
    overflow-y: auto;
    padding: 0.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    -webkit-overflow-scrolling: touch;
}

#session-list::-webkit-scrollbar,
#supporter-messages::-webkit-scrollbar { width: 3px; height: 3px; }
#session-list::-webkit-scrollbar-thumb,
#supporter-messages::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.session-item {
    width: 100%;
    text-align: left;
    background: transparent;
    border: 1px solid transparent;
    border-radius: 2px;
    padding: 0.7rem 0.75rem;
    cursor: pointer;
    color: var(--ink);
    font-size: 0.85rem;
    transition: background 0.15s, border-color 0.15s;
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
}
.session-item:hover { background: var(--surface-hover); border-color: var(--border); }
.session-item.selected { background: var(--surface-hover); border-color: var(--accent); }

.session-name {
    font-weight: 700;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: 0.85rem;
}

.session-meta {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.session-badge {
    font-size: 0.6rem;
    padding: 0.12rem 0.45rem;
    border-radius: 2px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.status-waiting { background: var(--status-waiting-bg); color: var(--status-waiting-ink); }
.status-active  { background: var(--status-active-bg);  color: var(--status-active-ink); }
.status-closed  { background: var(--status-closed-bg);  color: var(--status-closed-ink); }

.session-count { font-size: 0.7rem; color: var(--ink-dim); }
.session-id {
    font-size: 0.65rem;
    color: var(--ink-dim);
    letter-spacing: 0.04em;
}

.no-sessions {
    padding: 1.5rem 1rem;
    font-size: 0.82rem;
    color: var(--ink-dim);
    text-align: center;
    line-height: 1.6;
}

/* ---- Main panel ---- */
.main-panel {
    grid-column: 2;
    grid-row: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: stretch;
    overflow: hidden;
    min-width: 0;
    background: var(--bg);
    padding: 1rem;
}

.chat-shell {
    display: flex;
    flex-direction: column;
    width: min(860px, 100%);
    height: 100%;
    background: var(--bg-panel);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--border);
    border-radius: 3px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(26, 29, 34, 0.06);
    transition: background 0.3s ease, border-color 0.3s ease;
}

.main-header {
    display: flex;
    align-items: center;
    gap: 0.55rem;
    padding: 0.8rem 1rem;
    border-bottom: 1px solid var(--border);
    min-height: 50px;
    flex-shrink: 0;
}

.active-copy {
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
}

#active-session-name {
    font-weight: 700;
    font-size: 0.88rem;
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

#active-session-meta {
    font-size: 0.65rem;
    color: var(--ink-dim);
    white-space: nowrap;
    letter-spacing: 0.04em;
}

/* ---- Messages ---- */
#supporter-messages {
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    padding: 0.9rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    scroll-behavior: smooth;
    -webkit-overflow-scrolling: touch;
}

.empty-state {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--ink-dim);
    gap: 0.4rem;
    font-size: 0.85rem;
    text-align: center;
    padding: 1rem;
    line-height: 1.6;
}

.msg-wrap { display: flex; }
.msg-user-wrap { justify-content: flex-start; }
.msg-supporter-wrap { justify-content: flex-end; }

.msg-user, .msg-supporter {
    max-width: 78%;
    padding: 0.55rem 0.8rem;
    border-radius: 12px;
    font-size: 0.85rem;
    line-height: 1.55;
    overflow-wrap: anywhere;
}

.msg-user {
    background: var(--peer-bubble);
    color: var(--peer-bubble-ink);
    border-bottom-left-radius: 3px;
}

.msg-supporter {
    background: var(--own-bubble);
    color: var(--own-bubble-ink);
    border-bottom-right-radius: 3px;
}

.msg-label {
    display: block;
    font-size: 0.62rem;
    font-weight: 500;
    opacity: 0.7;
    margin-bottom: 2px;
    text-transform: uppercase;
    letter-spacing: 0.12em;
}

.msg-text { margin: 0; }

.msg-time {
    display: block;
    font-size: 0.6rem;
    opacity: 0.5;
    margin-top: 4px;
    text-align: right;
    letter-spacing: 0.04em;
}

.msg-system-wrap { display: flex; justify-content: center; margin: 0.25rem 0; }
.msg-system-text {
    font-size: 0.7rem;
    color: var(--ink-dim);
    background: var(--input-bg);
    padding: 0.25rem 0.75rem;
    border-radius: 2px;
    text-align: center;
    letter-spacing: 0.04em;
}

/* ---- Typing bubble ---- */
.typing-bubble {
    display: none;
    padding: 0 0.9rem 0.55rem;
    justify-content: flex-start;
    flex-shrink: 0;
}
.typing-bubble.visible { display: flex; }

.typing-bubble-inner {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    min-width: 48px;
    padding: 0.55rem 0.75rem;
    background: var(--peer-bubble);
    border-radius: 12px;
    border-bottom-left-radius: 3px;
}

.typing-dot {
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--ink-dim);
    animation: typing-bounce 1.1s infinite ease-in-out;
}
.typing-dot:nth-child(2) { animation-delay: 0.16s; }
.typing-dot:nth-child(3) { animation-delay: 0.32s; }

/* ---- Reply area ---- */
#reply-area {
    border-top: 1px solid var(--border);
    padding: 0.6rem 0.85rem max(0.75rem, env(safe-area-inset-bottom));
    display: none;
    flex-shrink: 0;
}
#reply-area.visible { display: flex; gap: 0.45rem; }

#reply-area input[type="text"] {
    flex: 1;
    min-width: 0;
    padding: 0.55rem 0.8rem;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 3px;
    color: var(--ink);
    font-size: 0.85rem;
    line-height: 1.25;
    outline: none;
    transition: border-color 0.2s;
}
#reply-area input[type="text"]:focus { border-color: var(--accent); }
#reply-area input[type="text"]::placeholder { color: var(--ink-dim); }

#reply-area button {
    padding: 0.55rem 0.9rem;
    background: var(--accent);
    color: var(--bg);
    border: none;
    border-radius: 3px;
    font-weight: 700;
    font-size: 0.78rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    cursor: pointer;
    transition: opacity 0.2s;
    white-space: nowrap;
}
#reply-area button:hover { opacity: 0.85; }

/* ---- Mobile ---- */
@media (max-width: 820px) {
    .layout {
        grid-template-columns: minmax(0, 1fr);
        grid-template-rows: auto minmax(0, 1fr);
    }

    .topbar { padding: 0 0.75rem; }
    .menu-button { display: inline-flex; }

    .drawer-backdrop.visible { display: block; }

    .sidebar {
        position: fixed;
        top: 0; left: 0; bottom: 0;
        height: 100%;
        height: var(--app-height, 100dvh);
        width: min(88vw, 320px);
        border-right: 1px solid var(--border);
        z-index: 50;
        transform: translateX(-102%);
        transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
        box-shadow: 12px 0 35px rgba(0, 0, 0, 0.25);
    }
    .sidebar.open { transform: translateX(0); }
    .close-sidebar { display: inline-flex; }

    .main-panel {
        grid-column: 1;
        grid-row: 2;
        padding: 0.65rem;
        align-items: stretch;
        justify-content: stretch;
    }

    .chat-shell {
        width: 100%;
        max-width: none;
        height: 100%;
    }

    .main-header { padding: 0.75rem 0.85rem; }
    .msg-user, .msg-supporter { max-width: 86%; }
    #reply-area.visible { gap: 0.4rem; }
    #reply-area button { padding-inline: 0.75rem; }
}

@media (max-width: 460px) {
    .nav-brand .brand-sub { display: none; }
    .nav-brand .brand-sep { display: none; }
    .main-panel { padding: 0.45rem; }
    .main-header { min-height: 46px; }
    #supporter-messages { padding: 0.75rem; }
    .theme-toggle { width: 20px; height: 20px; bottom: 1rem; right: 0.75rem; }
}

@keyframes typing-bounce {
    0%, 75%, 100% { transform: translateY(0); opacity: 0.45; }
    35% { transform: translateY(-4px); opacity: 1; }
}