:root {
    --brand: #EA580C;
    --brand-dark: #C2410C;
    --bg: #f7f7fb;
    --card: #ffffff;
    --text: #1f2330;
    --muted: #6b7280;
    --border: #e5e7eb;
    --success: #15803d;
    --error: #b91c1c;
    --radius: 14px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 20px;
    background: var(--card);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 10;
}

.brand { font-weight: 700; font-size: 18px; color: var(--brand); }
.topnav { display: flex; gap: 14px; }

.app { max-width: 920px; margin: 0 auto; padding: 24px 20px 64px; }

.link {
    background: none;
    border: none;
    color: var(--brand);
    font: inherit;
    cursor: pointer;
    padding: 4px 6px;
}
.link:hover { text-decoration: underline; }

button.primary {
    background: var(--brand);
    color: #fff;
    border: none;
    border-radius: 10px;
    padding: 11px 18px;
    font: inherit;
    font-weight: 600;
    cursor: pointer;
}
button.primary:hover { background: var(--brand-dark); }
button.primary:disabled { opacity: 0.5; cursor: default; }

button.ghost {
    background: var(--card);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 10px 16px;
    font: inherit;
    cursor: pointer;
}

.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    margin-bottom: 16px;
}

.card input[type="text"], .card input[type="date"] {
    width: 100%;
    padding: 11px 12px;
    margin: 6px 0;
    border: 1px solid var(--border);
    border-radius: 10px;
    font: inherit;
}

.muted { color: var(--muted); }
.error { color: var(--error); font-size: 14px; margin: 8px 0; }
.center { text-align: center; }
.row { display: flex; gap: 12px; align-items: center; }
.spread { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
h1 { font-size: 26px; margin: 6px 0 18px; }
h2 { font-size: 20px; margin: 0 0 12px; }

/* Auth */
.auth-wrap { max-width: 380px; margin: 48px auto; }
.auth-wrap input {
    width: 100%;
    padding: 11px 12px;
    margin: 6px 0;
    border: 1px solid var(--border);
    border-radius: 10px;
    font: inherit;
}
.auth-tabs { display: flex; gap: 8px; margin-bottom: 14px; }
.auth-tabs button { flex: 1; }
.auth-tabs button.active { background: var(--brand); color: #fff; border-color: var(--brand); }
.consent { font-size: 14px; color: var(--muted); margin: 8px 0; }
.consent label { display: flex; gap: 8px; align-items: flex-start; margin: 6px 0; }
.consent a { color: var(--brand); }

/* Course grid */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.course {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 18px;
    cursor: pointer;
    transition: box-shadow 0.15s, transform 0.15s;
}
.course:hover { box-shadow: 0 6px 18px rgba(0,0,0,0.08); transform: translateY(-2px); }
.course h3 { margin: 0 0 8px; font-size: 17px; }
.badge {
    display: inline-block;
    font-size: 12px;
    font-weight: 600;
    padding: 3px 9px;
    border-radius: 999px;
}
.badge.owned { background: #dcfce7; color: var(--success); }
.badge.locked { background: #f3f4f6; color: var(--muted); }

.taglist { list-style: none; padding: 0; margin: 10px 0; }
.taglist li { padding: 4px 0; color: var(--muted); font-size: 14px; }

/* Study */
.progressbar { height: 8px; background: var(--border); border-radius: 999px; overflow: hidden; }
.progressbar > div { height: 100%; background: var(--brand); }
.flashcard { min-height: 140px; font-size: 18px; line-height: 1.5; }
.grade-row { display: flex; gap: 10px; margin-top: 18px; }
.grade-row button { flex: 1; }
.grade-again { background: var(--error); }
.grade-easy { background: var(--brand-dark); }