:root {
    --bg: #ffffff;
    --fg: #101010;
    --muted: #666666;
    --line: #111111;
    --soft: #f6f6f6;
    --soft2: #eeeeee;
    --error: #111;
}
* { box-sizing: border-box; }
html { font-size: 16px; }
body {
    margin: 0;
    background: var(--bg);
    color: var(--fg);
    font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.45;
}
a { color: var(--fg); text-decoration-thickness: 1px; text-underline-offset: 0.2em; }
.top {
    position: sticky;
    top: 0;
    z-index: 10;
    background: rgba(255,255,255,0.96);
    border-bottom: 1px solid var(--line);
    padding: 0.9rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}
.brand { font-weight: 800; letter-spacing: .08em; text-transform: uppercase; text-decoration: none; }
.nav { display: flex; flex-wrap: wrap; gap: .55rem; justify-content: flex-end; }
.nav a {
    text-decoration: none;
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: .42rem .78rem;
    font-size: .92rem;
    background: #fff;
}
.nav a:hover { background: var(--fg); color: var(--bg); }
.main { width: min(1120px, 100%); margin: 0 auto; padding: 1rem; }
h1 { font-size: clamp(2rem, 8vw, 4.5rem); line-height: .94; letter-spacing: -.06em; margin: 2rem 0 1.2rem; }
h2 { font-size: 1.35rem; margin: 0 0 1rem; }
h3 { margin-top: 0; }
.card, .study-card {
    border: 1px solid var(--line);
    border-radius: 1.6rem;
    padding: clamp(1rem, 4vw, 2rem);
    margin: 1rem 0;
    background: #fff;
    box-shadow: 0 0 0 0 #000;
}
.study-card { min-height: 55vh; display: flex; flex-direction: column; justify-content: center; text-align: center; }
.study-card h2 { font-size: clamp(2rem, 10vw, 5rem); letter-spacing: -.06em; line-height: 1; margin: 1rem 0 2rem; }
.card-meta, .muted, small { color: var(--muted); }
.btn, button.btn, .time-btn {
    appearance: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: .4rem;
    min-height: 2.85rem;
    padding: .85rem 1.15rem;
    border-radius: 999px;
    border: 1px solid var(--line);
    background: var(--fg);
    color: var(--bg);
    text-decoration: none;
    font-weight: 700;
    cursor: pointer;
}
.btn.secondary { background: var(--bg); color: var(--fg); }
.btn:hover, .time-btn:hover { transform: translateY(-1px); }
.link-btn {
    border: 0;
    background: transparent;
    color: var(--fg);
    text-decoration: underline;
    cursor: pointer;
    padding: 0;
    font: inherit;
}
.danger-link {
    font-weight: 800;
    text-decoration-thickness: 2px;
}
.form-grid { display: grid; gap: 1rem; }
label { display: grid; gap: .35rem; font-weight: 700; }
input, textarea, select {
    width: 100%;
    border: 1px solid var(--line);
    border-radius: 1rem;
    padding: .85rem 1rem;
    background: #fff;
    color: var(--fg);
    font: inherit;
}
textarea { resize: vertical; }
.check { display: flex; align-items: center; gap: .6rem; }
.check input { width: auto; }
.interval-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .8rem; }
.time-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .75rem; }
.time-btn { aspect-ratio: 1.25 / 1; flex-direction: column; font-size: clamp(1.4rem, 6vw, 3rem); border-radius: 1.3rem; }
.time-btn span { font-size: .8rem; letter-spacing: .1em; text-transform: uppercase; }
.stats-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .75rem; }
.stat { border: 1px solid var(--line); border-radius: 1.2rem; padding: 1rem; background: var(--soft); }
.stat strong { display: block; font-size: clamp(1.7rem, 7vw, 3.5rem); line-height: 1; letter-spacing: -.06em; }
.stat span { color: var(--muted); font-size: .9rem; }
.notice { border: 1px solid var(--line); border-radius: 1rem; padding: .9rem 1rem; margin: 1rem 0; background: var(--soft); }
.notice.error { background: #fff; border-width: 2px; }
.notice.success { background: var(--soft2); }
.badge { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; padding: .3rem .65rem; margin: .15rem; font-size: .85rem; }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
table { border-collapse: collapse; width: 100%; min-width: 760px; }
th, td { border-bottom: 1px solid var(--line); padding: .75rem .55rem; text-align: left; vertical-align: top; }
th { font-size: .78rem; text-transform: uppercase; letter-spacing: .08em; }
tr.inactive { opacity: .45; }
.actions { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; }
.inline { display: inline; }
.filter-row { display: grid; gap: .65rem; grid-template-columns: 1fr; }
.trainer-status { display: flex; justify-content: space-between; align-items: center; gap: 1rem; margin: 1rem 0; }
.timer { font-size: 1.5rem; font-weight: 800; font-variant-numeric: tabular-nums; border: 1px solid var(--line); border-radius: 999px; padding: .35rem .8rem; }
.answer-panel { display: none; border-top: 1px solid var(--line); padding-top: 1.2rem; margin-top: 1.2rem; }
.revealed .answer-panel { display: block; }
.revealed .reveal { display: none; }
.answer-panel p { font-size: clamp(1.35rem, 5vw, 2.4rem); margin: .5rem 0 1.2rem; }
.answer-panel .notes { font-size: 1rem; color: var(--muted); }
.answer-actions { display: grid; grid-template-columns: 1fr 1fr; gap: .75rem; margin-top: 1rem; }
.abort-form { text-align: center; margin: 1rem; }
.login-card { max-width: 420px; margin-inline: auto; }
.footer { border-top: 1px solid var(--line); padding: 1rem; text-align: center; color: var(--muted); margin-top: 2rem; }
code { background: var(--soft); border: 1px solid var(--line); border-radius: .35rem; padding: .1rem .3rem; }
@media (min-width: 680px) {
    .main { padding: 1.5rem; }
    .stats-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
    .interval-grid { grid-template-columns: repeat(5, minmax(0, 1fr)); }
    .filter-row { grid-template-columns: 1fr 180px auto auto; align-items: end; }
}
@media (max-width: 620px) {
    .top { align-items: flex-start; flex-direction: column; }
    .nav { justify-content: flex-start; }
    .nav a { font-size: .85rem; padding: .36rem .62rem; }
    .time-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .card, .study-card { border-radius: 1.2rem; }
}