/* ── Tadao Ando Agent — Ando-Inspired UI ──
   Concrete grays, sharp edges, generous whitespace (ma),
   light/shadow effects, clean sans-serif typography. */

/* ── CSS Custom Properties ─────────────────────────────────────────── */
:root {
    --color-bg:       #f5f5f3;   /* warm concrete light */
    --color-surface:  #ffffff;
    --color-text:     #1a1a1a;
    --color-text-sub: #666666;
    --color-border:   #e0ddd8;

    /* Ando concrete palette */
    --color-concrete-dark: #2a2a2a;
    --color-concrete-mid:  #555555;
    --color-concrete-light:#999999;

    /* Message bubbles */
    --color-user-bg:   var(--color-surface);
    --color-assistant-bg: #e8e6e1;   /* warm concrete */

    /* Accent */
    --color-accent:  var(--color-concrete-dark);

    /* Spacing */
    --space-xs:  4px;
    --space-sm:  8px;
    --space-md:  16px;
    --space-lg:  24px;
    --space-xl:  40px;

    /* Typography */
    --font-sans: 'Helvetica Neue', 'Hiragino Sans', 'Noto Sans CJK SC',
                 'PingFang SC', 'Microsoft YaHei', sans-serif;

    /* No rounded corners — Ando doesn't use curves frivolously */
    --radius: 0px;
}

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

html, body {
    height: 100%;
    font-family: var(--font-sans);
    font-size: 15px;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

/* ── App Layout ────────────────────────────────────────────────────── */
#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
    max-width: 900px;
    margin: 0 auto;
    position: relative;
}

/* ── Header ────────────────────────────────────────────────────────── */
.header {
    border-bottom: 1px solid var(--color-border);
    background: var(--color-surface);
    position: sticky;
    top: 0;
    z-index: 10;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-sm) var(--space-lg);
}

.header-title {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.header-name {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: var(--color-concrete-dark);
}

.header-sub {
    font-size: 0.75rem;
    font-weight: 400;
    color: var(--color-concrete-light);
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

/* ── Icon Button ───────────────────────────────────────────────────── */
.btn-icon {
    background: none;
    border: 1px solid transparent;
    border-radius: var(--radius);
    color: var(--color-concrete-mid);
    cursor: pointer;
    padding: var(--space-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.15s, border-color 0.15s;
}

.btn-icon:hover {
    color: var(--color-concrete-dark);
    border-color: var(--color-border);
}

/* ── Chat Container ────────────────────────────────────────────────── */
.chat-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* ── Messages ──────────────────────────────────────────────────────── */
.messages {
    flex: 1;
    overflow-y: auto;
    padding: var(--space-lg);
    scroll-behavior: smooth;
}

/* Welcome Message */
.welcome {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--space-lg);
    min-height: 40vh;
    text-align: left;
}

.welcome-portrait {
    width: 96px;
    height: 96px;
    object-fit: cover;
    object-position: center top;
    box-shadow: 3px 3px 16px rgba(0, 0, 0, 0.2);
    flex-shrink: 0;
}

.welcome-text {
    padding: var(--space-lg);
    border-left: 2px solid var(--color-concrete-dark);
    max-width: 400px;
}

.welcome-text p {
    font-style: italic;
    font-size: 1.1rem;
    color: var(--color-concrete-dark);
    line-height: 1.8;
}

.welcome-sub {
    margin-top: var(--space-sm);
    font-style: normal;
    font-size: 0.85rem;
    color: var(--color-concrete-light);
}

/* Message Bubbles */
.message {
    margin-bottom: var(--space-md);
    display: flex;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to   { opacity: 1; transform: translateY(0); }
}

.message.user {
    justify-content: flex-end;
}

.message.assistant {
    justify-content: flex-start;
}

.message-bubble {
    max-width: 75%;
    padding: var(--space-md) var(--space-lg);
    line-height: 1.7;
    font-size: 0.95rem;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.message.user .message-bubble {
    background: var(--color-user-bg);
    border: 1px solid var(--color-border);
    color: var(--color-text);
}

.message.assistant .message-bubble {
    background: var(--color-assistant-bg);
    border-left: 2px solid var(--color-concrete-dark);
    color: var(--color-text);
}

/* Typing indicator */
.typing-indicator {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-lg);
    color: var(--color-concrete-light);
    font-size: 0.85rem;
}

.typing-bar {
    width: 40px;
    height: 2px;
    background: var(--color-concrete-light);
    position: relative;
    overflow: hidden;
}

.typing-bar::after {
    content: '';
    position: absolute;
    left: -20px;
    top: 0;
    width: 20px;
    height: 100%;
    background: var(--color-concrete-dark);
    animation: typingSweep 1.2s ease-in-out infinite;
}

@keyframes typingSweep {
    0%   { left: -20px; }
    100% { left: 40px; }
}

/* ── Chat Input ────────────────────────────────────────────────────── */
.chat-input-area {
    border-top: 1px solid var(--color-border);
    background: var(--color-surface);
    padding: var(--space-md) var(--space-lg);
}

.chat-form {
    display: flex;
    gap: var(--space-sm);
}

.chat-form input {
    flex: 1;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--space-md);
    font-size: 0.95rem;
    font-family: var(--font-sans);
    color: var(--color-text);
    background: var(--color-bg);
    outline: none;
    transition: border-color 0.15s;
}

.chat-form input:focus {
    border-color: var(--color-concrete-mid);
}

.chat-form input::placeholder {
    color: var(--color-concrete-light);
}

.btn-send {
    border: none;
    border-radius: var(--radius);
    background: var(--color-concrete-dark);
    color: var(--color-surface);
    cursor: pointer;
    padding: var(--space-md);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s;
}

.btn-send:hover {
    background: var(--color-concrete-mid);
}

.btn-send:disabled {
    background: var(--color-concrete-light);
    cursor: not-allowed;
}

/* ── Settings Panel ────────────────────────────────────────────────── */
.settings-panel {
    position: fixed;
    top: 0;
    right: 0;
    width: 380px;
    max-width: 90vw;
    height: 100vh;
    background: var(--color-surface);
    border-left: 1px solid var(--color-border);
    box-shadow: -4px 0 24px rgba(0, 0, 0, 0.08);
    z-index: 100;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    transition: transform 0.25s ease;
}

.settings-panel.hidden {
    transform: translateX(100%);
}

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

.settings-header h2 {
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.02em;
}

.settings-section {
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
}

.settings-section h3 {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-concrete-light);
    margin-bottom: var(--space-md);
}

/* Upload form */
.upload-form {
    display: flex;
    gap: var(--space-sm);
    align-items: center;
}

.upload-form input[type="file"] {
    flex: 1;
    font-size: 0.85rem;
    font-family: var(--font-sans);
}

.upload-status {
    margin-top: var(--space-sm);
    font-size: 0.8rem;
    color: var(--color-concrete-light);
}

/* Source list */
.source-list {
    list-style: none;
    margin-bottom: var(--space-md);
    max-height: 300px;
    overflow-y: auto;
}

.source-list li {
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--color-border);
    font-size: 0.85rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.source-list .source-meta {
    color: var(--color-concrete-light);
    font-size: 0.75rem;
}

.source-list .source-delete {
    background: none;
    border: none;
    color: var(--color-concrete-light);
    cursor: pointer;
    padding: var(--space-xs) var(--space-sm);
    font-size: 0.8rem;
    transition: color 0.15s;
}

.source-list .source-delete:hover {
    color: #cc3333;
}

.source-empty {
    color: var(--color-concrete-light);
    font-style: italic;
}

/* Small button */
.btn-small {
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    background: var(--color-bg);
    color: var(--color-concrete-mid);
    cursor: pointer;
    padding: var(--space-sm) var(--space-md);
    font-size: 0.8rem;
    font-family: var(--font-sans);
    transition: background 0.15s, color 0.15s;
}

.btn-small:hover {
    background: var(--color-concrete-dark);
    color: var(--color-surface);
}

/* ── Error Message ─────────────────────────────────────────────────── */
.message.error .message-bubble {
    background: #fff0f0;
    border-left: 2px solid #cc3333;
    color: #991111;
}

/* ── Responsive ────────────────────────────────────────────────────── */
@media (max-width: 640px) {
    .header-inner {
        padding: var(--space-sm) var(--space-md);
    }

    .welcome {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }

    .welcome-portrait {
        width: 72px;
        height: 72px;
    }

    .welcome-text {
        border-left: none;
        border-top: 2px solid var(--color-concrete-dark);
    }

    .messages {
        padding: var(--space-md);
    }

    .message-bubble {
        max-width: 90%;
    }

    .chat-input-area {
        padding: var(--space-sm) var(--space-md);
    }
}