:root {
  --pink: #ff7eb6;
  --pink-soft: #ffe0ef;
  --peach: #ffb86b;
  --yellow: #ffe066;
  --mint: #5ed6a0;
  --sky: #6fc8ff;
  --purple: #b39dd2;
  --ink: #3a2e3f;
  --muted: #8a7d90;
  --bg: #fff7fb;
  --card: #ffffff;
  --shadow: 0 6px 20px rgba(255, 126, 182, 0.18);
  --radius: 18px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background:
    radial-gradient(1200px 500px at 80% -10%, var(--pink-soft), transparent),
    radial-gradient(900px 500px at -10% 110%, #e3f6ff, transparent),
    var(--bg);
  color: var(--ink);
  font-family: system-ui, -apple-system, "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

.app {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px 64px;
}

/* Header */
.topbar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 4px;
  position: sticky;
  top: 0;
  background: linear-gradient(var(--bg), rgba(255, 247, 251, 0.85));
  backdrop-filter: blur(6px);
  z-index: 10;
}
.brand {
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--pink);
  display: flex;
  align-items: center;
  gap: 6px;
}
.spacer { flex: 1; }

.btn {
  appearance: none;
  border: none;
  border-radius: 999px;
  padding: 12px 20px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  background: linear-gradient(135deg, var(--pink), var(--peach));
  color: #fff;
  box-shadow: var(--shadow);
  transition: transform .08s ease, filter .15s ease;
}
.btn:hover { filter: brightness(1.05); }
.btn:active { transform: translateY(1px) scale(.99); }
.btn:disabled { opacity: .6; cursor: default; }
.btn.secondary {
  background: #fff;
  color: var(--pink);
  border: 2px solid var(--pink-soft);
  box-shadow: none;
}
.btn.ghost {
  background: transparent;
  color: var(--muted);
  box-shadow: none;
  padding: 8px 12px;
}
.btn.small { padding: 8px 14px; font-size: .9rem; }
.btn.danger { background: linear-gradient(135deg, #ff8a8a, #ff5d73); }

.nav-menu { position: relative; }
.nav-menu-btn {
  list-style: none;
  cursor: pointer;
  border: none;
  background: linear-gradient(135deg, var(--pink), var(--peach));
  color: #fff;
  border-radius: 999px;
  padding: 9px 16px;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1;
  user-select: none;
  box-shadow: var(--shadow);
  transition: filter .15s ease;
}
.nav-menu-btn:hover { filter: brightness(1.05); }
.nav-menu-btn::-webkit-details-marker { display: none; }
.nav-menu-drop {
  position: absolute;
  right: 0;
  top: calc(100% + 6px);
  background: var(--card);
  border-radius: 14px;
  box-shadow: var(--shadow);
  min-width: 150px;
  overflow: hidden;
  z-index: 20;
  display: flex;
  flex-direction: column;
}
.menu-item {
  background: none;
  border: none;
  padding: 12px 18px;
  text-align: left;
  cursor: pointer;
  font-size: .95rem;
  font-family: inherit;
  font-weight: 600;
  color: var(--ink);
}
.menu-item:hover { background: var(--pink-soft); }

/* Cards */
.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  margin: 16px 0;
}
h1 { font-size: 1.5rem; margin: 8px 0 16px; }
h2 { font-size: 1.2rem; margin: 0 0 12px; }

label { display: block; font-weight: 600; margin: 14px 0 6px; font-size: .95rem; }
input[type="text"], input[type="email"], input[type="password"], textarea {
  width: 100%;
  padding: 13px 14px;
  border: 2px solid var(--pink-soft);
  border-radius: 14px;
  font-size: 1rem;
  font-family: inherit;
  background: #fffdfe;
}
input:focus, textarea:focus { outline: none; border-color: var(--pink); }
textarea { resize: vertical; min-height: 90px; }

.msg { margin: 12px 0; padding: 10px 14px; border-radius: 12px; font-weight: 600; }
.msg.error { background: #ffe3e8; color: #c2304a; }
.msg.ok { background: #e2fbef; color: #1f8a5b; }

/* Login screen */
.login-wrap { max-width: 420px; margin: 8vh auto 0; }
.login-hero { text-align: center; margin-bottom: 8px; }
.login-hero .big-logo {
  width: 76px; height: 76px; margin: 0 auto 10px;
  background: linear-gradient(135deg, var(--pink), var(--peach));
  border-radius: 50%; display: grid; place-items: center;
  font-size: 2rem; color: #fff; box-shadow: var(--shadow);
}

/* Homework list */
.hw-list { display: grid; gap: 14px; }
.hw-item {
  display: flex; align-items: center; gap: 14px;
  background: var(--card); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 12px; cursor: pointer;
  border: 2px solid transparent; transition: border-color .15s ease;
}
.hw-item:hover { border-color: var(--pink-soft); }
.hw-thumb {
  width: 64px; height: 64px; border-radius: 14px; object-fit: cover;
  background: var(--pink-soft); flex: none;
}
.hw-meta { flex: 1; min-width: 0; }
.hw-title { font-weight: 700; }
.hw-sub { color: var(--muted); font-size: .85rem; }

.badge {
  display: inline-block; padding: 4px 12px; border-radius: 999px;
  font-size: .8rem; font-weight: 800;
}
.badge.submitted { background: var(--yellow); color: #7a5b00; }
.badge.marked { background: var(--mint); color: #0c5a3a; }
.badge.new { background: var(--pink); color: #fff; margin-left: 6px; }

.notif-dot {
  display: inline-grid; place-items: center; min-width: 22px; height: 22px;
  padding: 0 6px; border-radius: 999px; background: var(--pink); color: #fff;
  font-size: .75rem; font-weight: 800; margin-left: 6px;
}

.empty { text-align: center; color: var(--muted); padding: 32px 12px; }

.tabs { display: flex; gap: 8px; margin: 8px 0 4px; }
.tab {
  border: none; background: #fff; color: var(--muted);
  border-radius: 999px; padding: 10px 18px; font-weight: 700; cursor: pointer;
  box-shadow: var(--shadow);
}
.tab.active { background: linear-gradient(135deg, var(--pink), var(--peach)); color: #fff; }

/* Marking editor */
.tools {
  display: flex; flex-wrap: wrap; gap: 8px; align-items: center;
  position: sticky; top: 62px; z-index: 9;
  background: rgba(255, 247, 251, 0.92); backdrop-filter: blur(6px);
  padding: 10px 4px; margin: 0 -4px;
}
.tool {
  border: 2px solid var(--pink-soft); background: #fff; color: var(--ink);
  border-radius: 12px; padding: 9px 16px; font-weight: 700; cursor: pointer;
}
.stamp-btn { padding: 9px 13px; font-size: 1.1rem; }
.tool-divider { width: 1px; background: var(--pink-soft); align-self: stretch; margin: 2px 4px; }
.tool.active { background: var(--pink); color: #fff; border-color: var(--pink); }
.canvas-wrap {
  border-radius: 14px; overflow: auto; background: #faf3f7;
  border: 2px solid var(--pink-soft); max-width: 100%;
}
canvas { display: block; max-width: 100%; touch-action: none; }

.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.student-row {
  display: flex; align-items: center; gap: 10px; padding: 10px 0;
  border-bottom: 1px solid var(--pink-soft);
}
.student-row .name { font-weight: 700; flex: 1; }
.student-row.inactive { opacity: .55; }

.spin { text-align: center; color: var(--muted); padding: 28px; }
img.full { width: 100%; border-radius: 14px; border: 2px solid var(--pink-soft); }