:root {
    color-scheme: light;
    --bg: #ffffff;
    --surface: #f6f7f9;
    --text: #1d2330;
    --muted: #6b7280;
    --faint: #c4c8d0;
    --line: #e5e7eb;
    --accent: #2563eb;
    --free: #e6f4ea;
    --free-text: #14532d;
    --busy: #f1d5d5;
    --busy-text: #7f1d1d;
    --radius: 10px;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        color-scheme: dark;
        --bg: #12151b;
        --surface: #1a1e26;
        --text: #e6e8ec;
        --muted: #9aa1ad;
        --faint: #4b515c;
        --line: #2a2f39;
        --accent: #60a5fa;
        --free: #173323;
        --free-text: #a7e3bb;
        --busy: #3d1f22;
        --busy-text: #f5b5b5;
    }
}

:root[data-theme="dark"] {
    color-scheme: dark;
    --bg: #12151b;
    --surface: #1a1e26;
    --text: #e6e8ec;
    --muted: #9aa1ad;
    --faint: #4b515c;
    --line: #2a2f39;
    --accent: #60a5fa;
    --free: #173323;
    --free-text: #a7e3bb;
    --busy: #3d1f22;
    --busy-text: #f5b5b5;
}

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

html,
body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font: 15px/1.4 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
}

.cal {
    max-width: 1100px;
    margin: 0 auto;
    padding: 16px;
}

.cal-head {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 16px;
}

.cal-title {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: -0.01em;
}

.cal-nav {
    display: flex;
    gap: 6px;
}

.cal-btn {
    min-width: 40px;
    height: 36px;
    padding: 0 12px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text);
    font: inherit;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.15s, border-color 0.15s;
}

.cal-btn:hover:not(:disabled) {
    border-color: var(--accent);
}

.cal-btn:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.cal-btn:disabled {
    opacity: 0.4;
    cursor: default;
}

.cal-btn-today {
    font-size: 0.875rem;
}

.cal-months {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 16px;
}

.cal-month {
    width: 100%;
    border-collapse: separate;
    border-spacing: 3px;
    padding: 10px 8px 8px;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    table-layout: fixed;
}

.cal-month caption {
    padding: 0 0 8px;
    font-weight: 600;
    text-align: left;
    padding-left: 4px;
}

.cal-month th {
    padding: 2px 0 4px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--muted);
    text-align: center;
}

.cal-month th.we {
    color: var(--text);
}

.cal-month .kw {
    width: 2.2em;
    font-size: 0.6875rem;
    font-weight: 400;
    color: var(--faint);
}

.cal-month td {
    height: 34px;
    padding: 0;
    text-align: center;
    font-size: 0.875rem;
    font-variant-numeric: tabular-nums;
    border-radius: 6px;
}

.day.free {
    background: var(--free);
    color: var(--free-text);
}

.day.full {
    background: var(--busy);
    color: var(--busy-text);
}

/* changeover days: morning half (top-left) = night before, evening half = night after */
.day.dep {
    background: linear-gradient(135deg, var(--busy) 50%, var(--free) 50%);
    color: var(--text);
}

.day.arr {
    background: linear-gradient(135deg, var(--free) 50%, var(--busy) 50%);
    color: var(--text);
}

.day.past,
.day.na {
    color: var(--faint);
}

.day.today span {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    box-shadow: 0 0 0 2px var(--accent);
    font-weight: 600;
}

.cal-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 20px;
    margin: 16px 0 0;
    padding: 0;
    list-style: none;
    font-size: 0.8125rem;
    color: var(--muted);
}

.cal-legend li {
    display: flex;
    align-items: center;
    gap: 8px;
}

.sw {
    width: 16px;
    height: 16px;
    border-radius: 4px;
    border: 1px solid var(--line);
}

.sw-free { background: var(--free); }
.sw-full { background: var(--busy); }
.sw-dep { background: linear-gradient(135deg, var(--busy) 50%, var(--free) 50%); }
.sw-arr { background: linear-gradient(135deg, var(--free) 50%, var(--busy) 50%); }

.cal-error {
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--surface);
    color: var(--muted);
}

@media (max-width: 400px) {
    .cal-month .kw {
        display: none;
    }
}

@media (prefers-reduced-motion: reduce) {
    .cal-btn {
        transition: none;
    }
}