:root {
    --bg: #f5f5f7;
    --card: #ffffff;
    --ink: #1d1d1f;
    --muted: #6b7280;
    --line: #e5e7eb;
    --primary: #4f46e5;
    --primary-ink: #ffffff;
    --danger: #dc2626;
    --overdue: #dc2626;
    --today: #d97706;
    --upcoming: #059669;
    --radius: 14px;
    --shadow: 0 1px 3px rgba(0, 0, 0, .08), 0 1px 2px rgba(0, 0, 0, .04);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #0b0b0f;
        --card: #17171c;
        --ink: #f4f4f5;
        --muted: #9ca3af;
        --line: #2a2a31;
        --primary: #6366f1;
    }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--ink);
    line-height: 1.5;
    padding-bottom: env(safe-area-inset-bottom);
}

h1, h2, h3 { margin: 0 0 .4em; line-height: 1.2; }
a { color: var(--primary); }

.brand { font-weight: 700; font-size: 1.25rem; }
.subtitle { color: var(--muted); margin-top: -.3em; }

/* ---------- Buttons ---------- */
.btn {
    font: inherit;
    border: 1px solid transparent;
    border-radius: 10px;
    padding: .55em .9em;
    cursor: pointer;
    background: var(--card);
    color: var(--ink);
    border-color: var(--line);
    transition: filter .15s ease, opacity .15s ease;
}
.btn:hover { filter: brightness(.97); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn-primary { background: var(--primary); color: var(--primary-ink); border-color: var(--primary); }
.btn-ghost { background: transparent; }
.btn-danger { color: var(--danger); }
.btn-done { color: var(--upcoming); border-color: currentColor; }
.btn-postpone { color: var(--today); border-color: currentColor; }

/* ---------- Auth pages ---------- */
.auth-page {
    display: grid;
    place-items: center;
    min-height: 100vh;
    padding: 1rem;
}
.auth-card {
    background: var(--card);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 380px;
    text-align: center;
}
.auth-card form { text-align: left; display: grid; gap: 1rem; margin-top: 1.5rem; }
.auth-card label { display: grid; gap: .35rem; font-weight: 600; font-size: .9rem; }
.auth-card small { font-weight: 400; color: var(--muted); }
input[type=email], input[type=password], input[type=text], input[type=number], input[type=date] {
    font: inherit;
    padding: .6em .7em;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: var(--bg);
    color: var(--ink);
    width: 100%;
}
input:focus { outline: 2px solid var(--primary); outline-offset: 1px; }
.switch { margin-top: 1.25rem; color: var(--muted); font-size: .9rem; }

/* ---------- Alerts ---------- */
.alert { padding: .7em .9em; border-radius: 10px; margin-bottom: 1rem; font-size: .92rem; }
.alert-error { background: #fee2e2; color: #991b1b; }
.alert-info { background: #e0e7ff; color: #3730a3; }
@media (prefers-color-scheme: dark) {
    .alert-error { background: #3f1d1d; color: #fca5a5; }
    .alert-info { background: #1e1b4b; color: #c7d2fe; }
}

/* ---------- App shell ---------- */
.topbar {
    background: var(--card);
    border-bottom: 1px solid var(--line);
    position: sticky;
    top: 0;
    z-index: 10;
    padding-top: env(safe-area-inset-top);
}
.topbar-inner {
    max-width: 720px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: .5rem;
    padding: .7rem 1rem;
}
.topbar-actions { display: flex; align-items: center; gap: .5rem; flex-wrap: wrap; }
.user-email { color: var(--muted); font-size: .85rem; }
.inline { display: inline; margin: 0; }

.container { max-width: 720px; margin: 0 auto; padding: 1rem 1rem 4rem; }

.card {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.1rem;
    margin-bottom: 1rem;
}

/* ---------- Add form ---------- */
.task-form {
    display: flex;
    flex-wrap: wrap;
    gap: .75rem;
    align-items: end;
}
.field { display: grid; gap: .3rem; flex: 1 1 100%; }
.field label { font-weight: 600; font-size: .85rem; }
.field-sm { flex: 1 1 120px; }
.task-form .btn-primary { flex: 1 1 100%; }
.form-error { color: var(--danger); font-size: .88rem; margin: .5rem 0 0; }

@media (min-width: 520px) {
    .field { flex: 2 1 200px; }
    .task-form .btn-primary { flex: 0 0 auto; }
}

/* ---------- Task list ---------- */
.task-group { margin-top: 1.5rem; }
.task-group > h2 { font-size: 1rem; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }

.task {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    justify-content: space-between;
    border-left: 4px solid var(--line);
}
.task-overdue { border-left-color: var(--overdue); }
.task-today { border-left-color: var(--today); }
.task-upcoming { border-left-color: var(--upcoming); }
.task-main { min-width: 0; }
.task-title { font-size: 1.05rem; word-break: break-word; }
.task-meta { color: var(--muted); font-size: .85rem; margin: 0; }
.task-actions { display: flex; flex-wrap: wrap; gap: .4rem; justify-content: flex-end; }
.task-actions .btn { padding: .4em .6em; font-size: .9rem; }

.empty { text-align: center; color: var(--muted); padding: 2rem; }

.badge {
    display: inline-block;
    font-size: .72rem;
    padding: .1em .5em;
    border-radius: 999px;
    background: var(--line);
    color: var(--muted);
    margin-left: .4em;
    vertical-align: middle;
}

/* ---------- Toast ---------- */
#toast {
    position: fixed;
    left: 50%;
    bottom: calc(1rem + env(safe-area-inset-bottom));
    transform: translateX(-50%) translateY(200%);
    background: var(--ink);
    color: var(--bg);
    padding: .7em 1.1em;
    border-radius: 999px;
    font-size: .9rem;
    box-shadow: var(--shadow);
    transition: transform .25s ease;
    z-index: 50;
    max-width: 90vw;
}
#toast.show { transform: translateX(-50%) translateY(0); }