html {
    background-color: lightgreen;
}

body {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    font-family: system-ui, sans-serif;
}

main {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    box-sizing: border-box;
    max-width: 100%;
    padding: 2rem 1rem;
}

/* photos never wider than the screen (the profile photo has width="600") */
img {
    max-width: 100%;
    height: auto;
}

/* Navbar */
.site-header {
    --nav-bg: rgb(255 255 255 / 0.75);
    --nav-text: #1e293b;
    --nav-muted: #475569;
    --nav-hover: rgb(15 23 42 / 0.08);
    --nav-active-bg: #2563eb;
    --nav-active-text: #fff;

    position: sticky;
    top: 0;
    z-index: 10;
    align-self: stretch;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem 1rem;
    padding: 0.6rem 1rem;
    background: var(--nav-bg);
    backdrop-filter: blur(8px);
    box-shadow: 0 1px 0 rgb(15 23 42 / 0.1), 0 4px 16px rgb(15 23 42 / 0.06);
}

.header-end {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.25rem 0.75rem;
}

.main-nav,
.lang-switch {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
}

.site-header a {
    padding: 0.45rem 0.9rem;
    border-radius: 999px;
    color: var(--nav-text);
    font-weight: 600;
    text-decoration: none;
    transition: background-color 0.15s ease, color 0.15s ease;
}

.lang-switch a {
    color: var(--nav-muted);
    font-size: 0.9rem;
    font-weight: 500;
}

.site-header a:hover {
    background: var(--nav-hover);
    color: var(--nav-text);
}

.site-header a.active {
    background: var(--nav-active-bg);
    color: var(--nav-active-text);
}

.site-header a:focus-visible,
.logout-form button:focus-visible {
    outline: 3px solid rgb(37 99 235 / 0.5);
    outline-offset: 2px;
}

.logout-form {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    margin: 0;
}

.user-name {
    max-width: 14rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    color: var(--nav-muted);
    font-size: 0.9rem;
}

.logout-form button {
    padding: 0.45rem 0.9rem;
    border: none;
    border-radius: 999px;
    background: transparent;
    color: var(--nav-text);
    font: 600 1rem/1.2 system-ui, sans-serif;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.logout-form button:hover {
    background: var(--nav-hover);
}

/* one-line notice under the header (message sent, login failed, ...) */
.flash {
    --flash-bg: #e0f2fe;
    --flash-text: #075985;

    box-sizing: border-box;
    width: min(40rem, calc(100% - 2rem));
    margin: 1rem 0 0;
    padding: 0.75rem 1rem;
    border-radius: 0.75rem;
    background: var(--flash-bg);
    color: var(--flash-text);
    font-weight: 600;
    text-align: center;
}

.flash-success { --flash-bg: #dcfce7; --flash-text: #166534; }
.flash-error   { --flash-bg: #fee2e2; --flash-text: #991b1b; }

#message-me-btn {
    --btn-bg: #2563eb;
    --btn-bg-hover: #1d4ed8;
    --btn-text: #fff;

    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.4rem;
    border: none;
    border-radius: 999px;
    background: var(--btn-bg);
    color: var(--btn-text);
    font: 600 1rem/1.2 system-ui, sans-serif;
    cursor: pointer;
    box-shadow: 0 2px 8px rgb(37 99 235 / 0.35);
    transition: background-color 0.2s ease, transform 0.15s ease, box-shadow 0.2s ease;
}

#message-me-btn:hover {
    background: var(--btn-bg-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 14px rgb(37 99 235 / 0.45);
}

#message-me-btn:active {
    transform: translateY(0) scale(0.98);
}

#message-me-btn:focus-visible {
    outline: 3px solid rgb(37 99 235 / 0.5);
    outline-offset: 3px;
}

#message-me-btn:disabled {
    background: #94a3b8;
    box-shadow: none;
    transform: none;
    cursor: not-allowed;
}

@media (prefers-color-scheme: dark) {
    .site-header {
        --nav-bg: rgb(15 23 42 / 0.85);
        --nav-text: #e2e8f0;
        --nav-muted: #94a3b8;
        --nav-hover: rgb(255 255 255 / 0.08);
        --nav-active-bg: #3b82f6;
        --nav-active-text: #0b1220;
    }

    #message-me-btn {
        --btn-bg: #3b82f6;
        --btn-bg-hover: #60a5fa;
        --btn-text: #0b1220;
    }
}

@media (prefers-reduced-motion: reduce) {
    #message-me-btn,
    .site-header a,
    .logout-form button { transition: none; }
}