/* ── Reset / base ─────────────────────────────────────────── */

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

:root {
    --accent:        #1a73e8;
    --accent-hover:  #1558b0;
    --bg:            #e8e8e8;
    --surface:       #ffffff;
    --text-muted:    #555;
    --radius:        8px;
    --fab-size:      3.25rem;
    --ease:          0.22s ease;
}

body {
    margin: 0;
    padding: 0;
    font-family: system-ui, -apple-system, sans-serif;
    background: var(--bg);
}

/* ── Loading overlay ──────────────────────────────────────── */

#loading {
    position: fixed;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    background: var(--surface);
    z-index: 100;
    transition: opacity var(--ease);
}

#loading.hidden {
    opacity: 0;
    pointer-events: none;
}

.spinner {
    width: 2.5rem;
    height: 2.5rem;
    border: 3px solid #ddd;
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.75s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

#loading p {
    margin: 0;
    color: var(--text-muted);
    font-size: 0.875rem;
    letter-spacing: 0.01em;
}

/* ── PDF object ───────────────────────────────────────────── */

#pdf-viewer {
    display: block;
    width: 100%;
    height: 100vh;
    border: none;
}

/* ── Fallback ─────────────────────────────────────────────── */

.fallback {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    gap: 1.25rem;
    text-align: center;
    padding: 2rem;
    background: var(--surface);
}

.fallback [data-icon] {
    font-size: 3rem;
    line-height: 1;
    user-select: none;
}

.fallback p {
    margin: 0;
    color: var(--text-muted);
    font-size: 1rem;
    max-width: 28ch;
    line-height: 1.5;
}

/* ── Shared button ────────────────────────────────────────── */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.7rem 1.4rem;
    background: var(--accent);
    color: #fff;
    border-radius: var(--radius);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: background var(--ease), transform var(--ease);
}

.btn:hover  { background: var(--accent-hover); }
.btn:active { transform: scale(0.97); }

/* ── Floating Download Button (FAB) ───────────────────────── */

#fab {
    position: fixed;
    bottom: 1.5rem;
    right: 1.5rem;
    z-index: 200;
    width: var(--fab-size);
    height: var(--fab-size);
    border-radius: 50%;
    background: var(--accent);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.22);
    text-decoration: none;
    transition: background var(--ease), transform var(--ease), box-shadow var(--ease), opacity var(--ease);
    /* Start hidden; JS fades it in after load */
    opacity: 0;
    pointer-events: none;
}

#fab.visible {
    opacity: 1;
    pointer-events: auto;
}

#fab:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.28);
}

#fab:active {
    transform: translateY(0);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.18);
}

#fab svg {
    width: 1.2rem;
    height: 1.2rem;
    pointer-events: none;
    flex-shrink: 0;
}

/* Tooltip */
#fab::before {
    content: attr(aria-label);
    position: absolute;
    right: calc(100% + 0.6rem);
    background: rgba(0, 0, 0, 0.72);
    color: #fff;
    font-size: 0.76rem;
    white-space: nowrap;
    padding: 0.3rem 0.65rem;
    border-radius: 4px;
    pointer-events: none;
    opacity: 0;
    transition: opacity var(--ease);
}

#fab:hover::before {
    opacity: 1;
}