/* ============================================================
   index.css — 메인 문제 선택 화면
   Entry 디자인 토큰을 따릅니다.
   ============================================================ */

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: NanumGothic, 'Nanum Gothic', 'Malgun Gothic', sans-serif;
    background: #f9f8f7;
    color: #2c313d;
    min-height: 100vh;
    letter-spacing: -0.3px;
}

/* ---------- Header ---------- */
header {
    background: #2c313d;
    color: #fff;
    padding: 14px 24px;
    font-size: 16px;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: -0.3px;
}
.beta-badge {
    display: inline-block;
    padding: 2px 8px;
    background: #fa5536;
    color: #fff;
    font-size: 10px;
    font-weight: bold;
    border-radius: 3px;
    letter-spacing: 1px;
    vertical-align: middle;
}

/* ---------- Beta notice bar ---------- */
.beta-notice {
    background: #ecf8ff;
    border-bottom: 1px solid #d6e9f4;
    color: #2c313d;
    padding: 10px 24px;
    font-size: 12px;
    line-height: 1.5;
    letter-spacing: -0.3px;
}
.beta-notice::before {
    content: 'BETA';
    display: inline-block;
    background: #fa5536;
    color: #fff;
    font-size: 10px;
    font-weight: bold;
    padding: 1px 6px;
    border-radius: 3px;
    margin-right: 8px;
    letter-spacing: 1px;
    vertical-align: middle;
}

/* ---------- Container ---------- */
.container {
    max-width: 960px;
    margin: 28px auto;
    padding: 0 16px;
}
h2 {
    font-size: 16px;
    font-weight: bold;
    margin-bottom: 16px;
    color: #2c313d;
    letter-spacing: -0.3px;
}

/* ---------- Problem grid / cards ---------- */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 12px;
}
.card {
    background: #fff;
    border-radius: 6px;
    padding: 20px 16px;
    text-align: center;
    border: 1px solid #d6e9f4;
    transition: border-color 0.15s, box-shadow 0.15s, transform 0.1s;
    text-decoration: none;
    color: inherit;
    display: block;
    position: relative;
}
.card:hover {
    border-color: #4f80ff;
    box-shadow: 0 4px 12px rgba(79,128,255,0.18);
    transform: translateY(-1px);
}
.card.solved {
    border-color: #32d27d;
    background: #f3fbf7;
}
.card.solved:hover {
    border-color: #28b36a;
    box-shadow: 0 4px 12px rgba(50,210,125,0.22);
}
.card-solved-badge {
    position: absolute;
    top: 8px;
    right: 8px;
    background: #32d27d;
    color: #fff;
    font-size: 10px;
    font-weight: bold;
    padding: 2px 7px;
    border-radius: 3px;
    letter-spacing: -0.2px;
}
.card-number {
    font-size: 30px;
    font-weight: bold;
    color: #4f80ff;
    margin-bottom: 6px;
    letter-spacing: -0.5px;
}
.card.solved .card-number { color: #28b36a; }
.card-title {
    font-size: 13px;
    color: #555;
    font-weight: bold;
    letter-spacing: -0.3px;
}
.card-difficulty {
    margin-top: 10px;
    font-size: 13px;
    letter-spacing: 2px;
}
.card-difficulty .star-filled { color: #ffcf5f; }
.card-difficulty .star-empty  { color: #e2e2e2; }

/* ---------- Empty state ---------- */
.empty {
    text-align: center;
    color: #8ba4b3;
    padding: 60px;
    font-size: 14px;
    background: #fff;
    border: 1px solid #d6e9f4;
    border-radius: 6px;
}

/* ---------- Free mode section ---------- */
.free-section {
    text-align: center;
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid #d6e9f4;
}
.free-link {
    display: inline-block;
    padding: 10px 24px;
    background: #fff;
    color: #4f80ff;
    border: 1px solid #4f80ff;
    border-radius: 4px;
    text-decoration: none;
    font-weight: bold;
    font-size: 13px;
    letter-spacing: -0.3px;
    transition: background 0.15s, color 0.15s;
}
.free-link:hover {
    background: #4f80ff;
    color: #fff;
}

/* ---------- Disclaimer footer ---------- */
.disclaimer {
    max-width: 960px;
    margin: 24px auto 32px;
    padding: 0 16px;
    text-align: center;
    font-size: 11px;
    line-height: 1.6;
    color: #8ba4b3;
    letter-spacing: -0.2px;
}
.disclaimer a {
    color: #8ba4b3;
    text-decoration: underline;
    text-underline-offset: 2px;
}
.disclaimer a:hover {
    color: #4f80ff;
}