*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --bg: #d8e6fb;
  --bg2: #eef4ff;
  --surface: rgba(255,255,255,.72);
  --surface-strong: rgba(255,255,255,.86);
  --surface-soft: rgba(255,255,255,.5);
  --border: rgba(157, 182, 219, .38);
  --border-strong: rgba(118, 150, 198, .45);
  --accent: #3e8fff;
  --accent2: #79c7ff;
  --text: #18314f;
  --sub: rgba(24,49,79,.82);
  --muted: rgba(24,49,79,.58);
  --link: #1f6fff;
  --easy: #2fba88;
  --green: #2fba88;
  --shadow: 0 26px 60px rgba(79, 107, 148, .18);
  --shadow-soft: 0 12px 28px rgba(108, 138, 176, .14);
  --glass-blur: blur(16px);
  --glass-saturate: saturate(180%);
  --highlight: inset 0 1px 0 rgba(255,255,255,.82);
}
html { font-size: 14px; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at 12% 18%, rgba(255,255,255,.92), transparent 28%),
    radial-gradient(circle at 82% 12%, rgba(130,205,255,.32), transparent 24%),
    radial-gradient(circle at 50% 100%, rgba(121,167,255,.16), transparent 40%),
    linear-gradient(160deg, var(--bg2), var(--bg));
  color: var(--text); min-height: 100vh;
  position: relative;
}
body::before {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(120deg, rgba(255,255,255,.08), transparent 35%, rgba(255,255,255,.04) 60%, transparent 72%),
    radial-gradient(circle at 20% 20%, rgba(255,255,255,.18), transparent 18%),
    radial-gradient(circle at 78% 24%, rgba(255,255,255,.1), transparent 16%);
  opacity: .75;
  z-index: -1;
}

/* NAV */
.nav {
  height: 74px;
  background: rgba(255,255,255,.76);
  border-bottom: 1px solid rgba(160, 186, 220, .3);
  box-shadow: var(--highlight), 0 10px 28px rgba(120, 149, 183, .14);
  backdrop-filter: var(--glass-saturate) var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-saturate) var(--glass-blur);
  display: flex; align-items: center; padding: 0 28px; gap: 18px;
  position: sticky; top: 0; z-index: 100;
  will-change: transform;
  transform: translateZ(0);
  backface-visibility: hidden;
}
.nav-brand { display: flex; flex-direction: column; gap: 2px; }
.nav-logo {
  font-family: 'Bangers', cursive; font-size: 30px; letter-spacing: 3px;
  color: var(--text); text-transform: uppercase; line-height: 1;
  text-shadow: 0 1px 0 rgba(255,255,255,.8), 0 8px 18px rgba(62,143,255,.1);
}
.nav-logo span { color: var(--accent); }
.nav-tagline { font-size: 10px; color: var(--muted); letter-spacing: 1.5px; text-transform: uppercase; font-weight: 600; }
.nav-right { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.nav-stats { font-size: 13px; color: var(--sub); font-weight: 600; letter-spacing: .5px; }
.nav-stats b { color: var(--accent); font-family: 'Bangers', cursive; font-size: 20px; letter-spacing: 1px; }
.reset-btn {
  border: 1px solid var(--border); background: var(--surface-strong); color: var(--sub);
  padding: 8px 14px; border-radius: 999px; cursor: pointer; font-size: 11px;
  font-weight: 800; text-transform: uppercase; letter-spacing: 1px;
  box-shadow: var(--highlight), var(--shadow-soft); transition: all .18s ease;
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.reset-btn:hover { border-color: rgba(229,57,53,.35); color: #d63c51; transform: translateY(-1px); box-shadow: var(--highlight), 0 16px 34px rgba(127, 147, 174, .18); }

/* SETTINGS DROPDOWN */
.settings-wrap { position: relative; }
.settings-gear {
  border: 1px solid var(--border); background: var(--surface-strong); color: var(--sub);
  width: 38px; height: 38px; border-radius: 999px; cursor: pointer;
  font-size: 16px; box-shadow: var(--highlight), var(--shadow-soft); transition: all .18s ease;
  display: flex; align-items: center; justify-content: center;
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.settings-gear:hover { border-color: rgba(62,143,255,.35); color: var(--accent); transform: translateY(-1px); }
.settings-dropdown {
  display: none; position: absolute; right: 0; top: calc(100% + 6px);
  background: rgba(255,255,255,.9); border: 1px solid var(--border); border-radius: 20px;
  box-shadow: var(--highlight), 0 24px 50px rgba(92, 117, 153, .2); min-width: 180px; z-index: 200;
  backdrop-filter: var(--glass-saturate) blur(24px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(24px);
  overflow: hidden;
}
.settings-dropdown.open { display: block; }
.settings-dropdown button {
  display: block; width: 100%; text-align: left;
  padding: 12px 18px; background: none; border: none; border-bottom: 1px solid rgba(255,255,255,.42);
  cursor: pointer; font-size: 12px; font-weight: 600; color: var(--sub);
  letter-spacing: .4px; transition: background .18s ease, color .18s ease;
}
.settings-dropdown button:last-child { border-bottom: none; }
.settings-dropdown button:hover { background: rgba(255,255,255,.24); color: var(--accent); }
.settings-dropdown .danger:hover { background: rgba(255,89,89,.1); color: #e53935; }

/* AUTH BUTTON */
.auth-btn {
  border: 1px solid rgba(62,143,255,.2); background: linear-gradient(180deg, rgba(255,255,255,.96), rgba(238,246,255,.92)); color: var(--accent);
  padding: 8px 14px; border-radius: 999px; cursor: pointer; font-size: 11px;
  font-weight: 700; letter-spacing: .5px; text-transform: uppercase;
  box-shadow: var(--highlight), 0 16px 28px rgba(62,143,255,.14); transition: all .18s ease; white-space: nowrap;
  backdrop-filter: var(--glass-saturate) blur(18px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(18px);
}
.auth-btn:hover { background: linear-gradient(180deg, rgba(109,184,255,.72), rgba(62,143,255,.9)); color: #fff; transform: translateY(-1px); }
.auth-btn.signed-in { border-color: rgba(255,255,255,.42); color: var(--sub); }
.auth-btn.signed-in:hover { background: linear-gradient(180deg, rgba(255,127,127,.72), rgba(229,57,53,.9)); border-color: rgba(229,57,53,.2); color: #fff; }

/* SIGN-IN MODAL */
.signin-modal {
  display: none; position: fixed; inset: 0; background: rgba(20,32,55,.24);
  z-index: 1000; align-items: center; justify-content: center;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}
.signin-modal.open { display: flex; }
.signin-box {
  background: rgba(255,255,255,.88); border: 1px solid var(--border); border-radius: 28px;
  box-shadow: var(--highlight), 0 30px 70px rgba(82, 108, 144, .24); padding: 32px 28px; min-width: 280px; text-align: center;
  backdrop-filter: var(--glass-saturate) blur(26px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(26px);
}
.signin-title { font-family: 'Bangers', cursive; font-size: 24px; letter-spacing: 2px; margin-bottom: 6px; }
.signin-sub { font-size: 12px; color: var(--muted); margin-bottom: 24px; }
.signin-providers { display: flex; flex-direction: column; gap: 10px; }
.signin-provider-btn {
  display: flex; align-items: center; gap: 10px; padding: 10px 16px;
  border: 1px solid var(--border); border-radius: 18px; background: rgba(255,255,255,.78);
  cursor: pointer; font-size: 13px; font-weight: 600; color: #333;
  box-shadow: var(--highlight), var(--shadow-soft); transition: all .18s ease;
}
.signin-provider-btn:hover { border-color: rgba(62,143,255,.35); color: var(--accent); transform: translateY(-1px); }
.signin-provider-btn svg { flex-shrink: 0; }
.signin-cancel { margin-top: 16px; font-size: 12px; color: var(--muted); cursor: pointer; background: none; border: none; }
.signin-cancel:hover { color: #e53935; }

/* CONTAINER */
.container { max-width: 1200px; margin: 0 auto; padding: 28px 24px; }
.section-hidden { display: none !important; }

/* LIST TABS */
.list-tabs {
  display: flex;
  border: 1px solid var(--border); border-radius: 28px;
  margin-bottom: 24px;
  box-shadow: var(--highlight), 0 22px 44px rgba(103, 132, 168, .14);
  overflow: hidden;
  background: rgba(255,255,255,.64);
  backdrop-filter: var(--glass-saturate) blur(22px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(22px);
  contain: paint;
}
.list-tab {
  flex: 1; padding: 14px 8px; text-align: center;
  font-family: 'Bangers', cursive; font-size: 17px; letter-spacing: 1.5px;
  text-transform: uppercase; cursor: pointer;
  border: none; background: transparent; color: rgba(24,49,79,.62); transition: all .18s ease;
  border-right: 1px solid rgba(157,182,219,.24);
}
.list-tab:last-child { border-right: none; }
.list-tab.on { background: linear-gradient(180deg, rgba(113,165,255,.92), rgba(78,139,241,.92)); color: #fff; text-shadow: 0 1px 8px rgba(13,63,132,.24); }
.list-tab:hover:not(.on) { background: rgba(255,255,255,.36); color: var(--accent); }

/* OVERVIEW */
.overview-panel {
  display: flex; flex-direction: column; gap: 18px; margin-bottom: 18px;
}
.overview-hero,
.overview-block,
.stat-card,
.sheet-stat-card {
  background: rgba(255,255,255,.72); border: 1px solid var(--border); border-radius: 30px;
  box-shadow: var(--highlight), 0 24px 48px rgba(99, 123, 156, .15);
  backdrop-filter: var(--glass-saturate) blur(24px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(24px);
}
.overview-hero {
  display: grid; grid-template-columns: minmax(0, 1.6fr) 220px; gap: 20px; align-items: center;
  padding: 28px;
}
.overview-kicker,
.stat-label {
  font-size: 11px; font-weight: 900; letter-spacing: 1.6px; text-transform: uppercase; color: var(--muted);
}
.overview-copy h1 {
  font-family: 'Bangers', cursive; font-size: 44px; line-height: .95; letter-spacing: 2px; margin: 10px 0 14px;
}
.overview-copy p {
  max-width: 600px; font-size: 15px; line-height: 1.6; color: var(--sub);
}
.overview-ring-wrap { display: flex; justify-content: center; }
.overview-ring {
  --pct: 0;
  width: 180px; aspect-ratio: 1; border-radius: 50%;
  background: conic-gradient(var(--accent) calc(var(--pct) * 1%), rgba(255,255,255,.25) 0);
  display: grid; place-items: center;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.42), 0 20px 40px rgba(62,143,255,.16);
}
.overview-ring-inner {
  width: calc(100% - 22px); height: calc(100% - 22px); border-radius: 50%;
  background: rgba(255,255,255,.88); display: flex; flex-direction: column; align-items: center; justify-content: center;
  text-align: center; box-shadow: inset 0 1px 0 rgba(255,255,255,.8);
}
.overview-ring-inner strong {
  font-family: 'Bangers', cursive; font-size: 42px; line-height: 1; letter-spacing: 2px;
}
.overview-ring-inner span {
  margin-top: 6px; font-size: 11px; letter-spacing: 1.4px; text-transform: uppercase; color: var(--muted);
}
.overview-cards,
.sheet-stats-grid {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; margin-bottom: 16px;
}
.stat-card,
.sheet-stat-card {
  padding: 18px 20px;
}
.stat-card strong,
.sheet-stat-card strong {
  display: block; margin: 10px 0 4px; font-family: 'Bangers', cursive; font-size: 30px; letter-spacing: 1.5px;
}
.stat-meta {
  display: block; color: var(--sub); line-height: 1.5; font-size: 12px;
}
.overview-split {
  display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr); gap: 18px;
}
.overview-block {
  padding: 22px;
}
.overview-block-head {
  display: flex; justify-content: space-between; gap: 12px; align-items: end; margin-bottom: 16px;
}
.overview-block-head h2 {
  font-family: 'Bangers', cursive; font-size: 28px; letter-spacing: 1.5px;
}
.overview-block-head span {
  color: var(--muted); font-size: 12px; text-align: right;
}
.sheet-progress-list,
.topic-stat-list {
  display: grid; gap: 12px;
}
.sheet-progress-card {
  border: 1px solid var(--border); background: rgba(255,255,255,.54); border-radius: 24px;
  padding: 16px; text-align: left; cursor: pointer; color: inherit;
  box-shadow: var(--highlight), var(--shadow-soft); transition: transform .18s ease, border-color .18s ease;
}
.sheet-progress-card:hover,
.topic-stat-card:hover {
  transform: translateY(-1px); border-color: rgba(62,143,255,.3);
}
.sheet-progress-top,
.sheet-progress-foot,
.topic-stat-card {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.sheet-progress-top strong,
.topic-stat-card strong {
  font-size: 14px; color: var(--text);
}
.sheet-progress-top span,
.sheet-progress-foot span,
.topic-stat-card span {
  font-size: 12px; color: var(--sub);
}
.mini-track {
  height: 10px; border-radius: 999px; overflow: hidden; margin: 12px 0 10px;
  background: rgba(226,236,252,.9); border: 1px solid rgba(173,196,230,.34);
}
.mini-fill {
  height: 100%; width: 0;
  background: linear-gradient(90deg, var(--accent), var(--accent2), #8be0ff);
  border-radius: inherit;
}
.topic-stat-card {
  border: 1px solid var(--border); border-radius: 22px; padding: 14px 16px;
  background: rgba(255,255,255,.56); box-shadow: var(--highlight), var(--shadow-soft);
  transition: transform .18s ease, border-color .18s ease;
}
.topic-stat-card b {
  font-family: 'Bangers', cursive; font-size: 24px; letter-spacing: 1px; color: var(--accent);
}

/* SHEET STATS */
.sheet-stats-grid {
  margin-top: 2px;
}

/* PROGRESS */
.progress-section {
  background: rgba(255,255,255,.72); border: 1px solid var(--border); border-radius: 28px;
  padding: 16px 20px; margin-bottom: 16px;
  box-shadow: var(--highlight), 0 18px 40px rgba(109, 135, 169, .14);
  backdrop-filter: var(--glass-saturate) blur(22px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(22px);
  contain: paint;
}
.prog-label {
  font-family: 'Bangers', cursive; font-size: 20px; letter-spacing: 2px;
  color: var(--text); margin-bottom: 10px; text-transform: uppercase;
}
.prog-track {
  height: 14px; background: rgba(226,236,252,.9); border-radius: 999px; overflow: hidden;
  border: 1px solid rgba(173,196,230,.34);
}
.prog-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent2), #8be0ff);
  border-radius: 999px; transition: width .6s ease; width: 0;
  box-shadow: 0 0 18px rgba(62,143,255,.35);
}

/* FILTER BAR */
.filter-bar { display: flex; gap: 10px; margin-bottom: 16px; flex-wrap: wrap; align-items: center; }
.f-search { flex: 1; min-width: 180px; max-width: 280px; position: relative; }
.f-search svg { position: absolute; left: 10px; top: 50%; transform: translateY(-50%); color: var(--muted); pointer-events: none; }
.f-search input {
  width: 100%; background: rgba(255,255,255,.84); border: 1px solid var(--border); border-radius: 18px;
  padding: 8px 10px 8px 30px; color: var(--text); font-size: 13px; font-weight: 600;
  outline: none; transition: border-color .15s, background .15s, box-shadow .15s; box-shadow: var(--highlight), var(--shadow-soft);
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.f-search input:focus { border-color: rgba(62,143,255,.36); background: rgba(255,255,255,.46); box-shadow: var(--highlight), 0 14px 34px rgba(62,143,255,.12); }
.f-search input::placeholder { color: var(--muted); font-weight: 400; }
.f-select {
  background: rgba(255,255,255,.84); border: 1px solid var(--border); border-radius: 18px;
  padding: 8px 28px 8px 12px; color: var(--text); font-size: 13px; font-weight: 600;
  cursor: pointer; outline: none; transition: border-color .15s;
  -webkit-appearance: none; appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath fill='%23999' d='M0 0l5 6 5-6z'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 10px center;
  box-shadow: var(--highlight), var(--shadow-soft);
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.f-select:focus { border-color: rgba(62,143,255,.36); }
.f-select option { background: #fff; }
.status-tabs { display: flex; background: rgba(255,255,255,.72); border: 1px solid var(--border); border-radius: 18px; overflow: hidden; box-shadow: var(--highlight), var(--shadow-soft); backdrop-filter: var(--glass-saturate) blur(16px); -webkit-backdrop-filter: var(--glass-saturate) blur(16px); }
.s-tab {
  padding: 8px 18px; font-family: 'Bangers', cursive; font-size: 16px; letter-spacing: 1px;
  text-transform: uppercase; cursor: pointer; border: none; background: none;
  color: rgba(24,49,79,.62); border-right: 1px solid rgba(157,182,219,.24); transition: all .18s ease;
}
.s-tab:last-child { border-right: none; }
.s-tab:hover:not(.on) { color: var(--text); background: rgba(255,255,255,.36); }
.s-tab.on { background: linear-gradient(180deg, rgba(113,165,255,.92), rgba(78,139,241,.92)); color: #fff; font-weight: 900; }

/* PROBLEM TABLE */
.ptable {
  background: rgba(255,255,255,.72); border: 1px solid var(--border); border-radius: 30px; overflow: hidden;
  box-shadow: var(--highlight), 0 30px 55px rgba(99, 123, 156, .15);
  backdrop-filter: var(--glass-saturate) blur(26px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(26px);
  contain: paint;
}
.pt-header {
  display: grid; grid-template-columns: 48px 36px 1fr 170px 100px;
  padding: 14px 20px; border-bottom: 1px solid rgba(173,196,230,.24);
  font-size: 10px; font-weight: 900; text-transform: uppercase; letter-spacing: 1.5px; color: rgba(24,49,79,.52);
  background: rgba(246,250,255,.72);
}

/* TOPIC GROUP */
.tg-header {
  display: flex; align-items: center; gap: 12px; padding: 13px 20px;
  border-left: 6px solid; border-bottom: 1px solid rgba(173,196,230,.18);
  cursor: pointer; user-select: none; transition: filter .18s ease, background .18s ease;
}
.tg-header:hover { filter: brightness(.98); }
.tg-arrow { font-size: 11px; transition: transform .2s; display: inline-block; }
.tg-arrow.col { transform: rotate(-90deg); }
.tg-name {
  font-family: 'Bangers', cursive; font-size: 22px; letter-spacing: 2px; text-transform: uppercase;
}
.tg-count { font-size: 12px; color: var(--sub); font-weight: 700; letter-spacing: .5px; }
.tg-rows.hidden { display: none; }

/* PROBLEM ROW */
.p-row {
  display: grid; grid-template-columns: 48px 36px 1fr 170px 100px;
  padding: 0 20px; min-height: 54px; align-items: center;
  border-bottom: 1px solid rgba(173,196,230,.18); transition: background .18s ease, transform .18s ease;
  border-left: 4px solid transparent;
}
.p-row:last-child { border-bottom: none; }
.p-row:hover { background: rgba(255,255,255,.42); }
.p-row.solved .p-name,
.p-row.solved .p-name-plain { text-decoration: line-through; text-decoration-color: rgba(23,48,79,.22); color: rgba(23,48,79,.38); }

/* ROW NUM */
.p-rownum { font-size: 11px; color: var(--muted); font-weight: 700; }

/* CHECKBOX */
.p-chk {
  width: 20px; height: 20px; border: 1px solid rgba(165,190,226,.54); border-radius: 999px;
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  transition: all .18s ease; flex-shrink: 0; box-shadow: var(--highlight), 0 8px 20px rgba(110, 136, 169, .16);
  background: rgba(255,255,255,.88);
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.p-chk:hover { border-color: var(--accent); }
.p-chk.on { border-color: rgba(62,143,255,.28); box-shadow: 0 8px 20px rgba(62,143,255,.2); }
.p-chk.on::after { content: '\2713'; font-size: 12px; color: #fff; font-weight: 900; }

/* TITLE */
.p-title-cell { display: flex; align-items: center; gap: 8px; min-width: 0; overflow: hidden; }
.p-name {
  font-size: 14px; font-weight: 600; color: var(--link); text-decoration: none;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.p-name:hover { text-decoration: underline; }
.p-name-plain { font-size: 14px; font-weight: 600; color: var(--text); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.p-ext { color: rgba(24,49,79,.34); font-size: 13px; text-decoration: none; flex-shrink: 0; transition: color .1s; }
.p-ext:hover { color: rgba(24,49,79,.7); }

/* TOPIC CHIP */
.topic-chip {
  display: inline-block; padding: 5px 11px; border-radius: 999px; border: 1px solid;
  font-size: 11px; font-weight: 800; text-transform: uppercase; letter-spacing: .8px;
  white-space: nowrap; max-width: 160px; overflow: hidden; text-overflow: ellipsis;
  box-shadow: inset 0 1px 0 rgba(255,255,255,.35);
}

/* SOLVE BUTTON */
.solve-btn {
  display: inline-block; font-size: 11px; font-weight: 900;
  font-family: 'Bangers', cursive; letter-spacing: 1.5px; text-transform: uppercase;
  text-decoration: none; border: 1px solid; border-radius: 999px;
  padding: 7px 14px; transition: all .18s ease; white-space: nowrap;
  box-shadow: inset 0 1px 0 rgba(255,255,255,.45), 0 10px 24px rgba(97, 127, 164, .14);
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.solve-btn:hover { transform: translateY(-1px); box-shadow: inset 0 1px 0 rgba(255,255,255,.45), 0 14px 28px rgba(97, 127, 164, .18); filter: brightness(.98); }
.no-solve { color: var(--muted); font-size: 13px; }

/* NOTES BUTTON */
.p-action { display: flex; align-items: center; gap: 8px; }
.notes-btn {
  width: 28px; height: 28px; border: 1px solid var(--border); border-radius: 999px;
  background: rgba(255,255,255,.84); color: var(--muted); cursor: pointer; font-size: 13px; line-height: 1;
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--highlight), var(--shadow-soft); transition: all .18s ease; flex-shrink: 0; padding: 0;
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.notes-btn:hover { border-color: rgba(62,143,255,.36); color: var(--accent); transform: translateY(-1px); }
.notes-btn.has-note { border-color: rgba(240,182,46,.34); color: #c98a00; background: rgba(255,245,204,.5); box-shadow: inset 0 1px 0 rgba(255,255,255,.5), 0 10px 24px rgba(201,138,0,.12); }
.notes-btn.has-note:hover { filter: brightness(.92); }

/* NOTES MODAL */
.note-modal {
  position: fixed; inset: 0; background: rgba(20,32,55,.24); z-index: 1000;
  display: flex; align-items: center; justify-content: center; padding: 20px;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}
.note-modal-box {
  background: rgba(255,255,255,.9); border: 1px solid var(--border); border-radius: 30px;
  box-shadow: var(--highlight), 0 35px 80px rgba(83, 108, 144, .24); width: 100%; max-width: 560px;
  display: flex; flex-direction: column; gap: 16px; padding: 24px;
  backdrop-filter: var(--glass-saturate) blur(30px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(30px);
}
.note-modal-title {
  font-family: 'Bangers', cursive; font-size: 18px; letter-spacing: 1.5px;
  color: var(--text); text-transform: uppercase; line-height: 1.3;
}
.note-textarea {
  width: 100%; min-height: 160px; padding: 14px 16px; border: 1px solid var(--border);
  border-radius: 24px; font-size: 14px; font-family: inherit; resize: vertical;
  line-height: 1.6; outline: none; box-shadow: inset 2px 2px 0 #eee;
  color: var(--text); background: rgba(255,255,255,.9);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.45), 0 10px 24px rgba(112, 135, 166, .12);
  backdrop-filter: var(--glass-saturate) blur(20px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(20px);
}
.note-textarea:focus { border-color: rgba(62,143,255,.35); box-shadow: inset 0 1px 0 rgba(255,255,255,.45), 0 14px 32px rgba(62,143,255,.12); }
.note-modal-btns { display: flex; gap: 10px; justify-content: flex-end; }
.note-save-btn {
  font-family: 'Bangers', cursive; font-size: 16px; letter-spacing: 1.5px;
  text-transform: uppercase; border: 1px solid rgba(62,143,255,.2); background: linear-gradient(180deg, rgba(119,195,255,.72), rgba(62,143,255,.9));
  color: #fff; padding: 10px 22px; border-radius: 999px; cursor: pointer;
  box-shadow: inset 0 1px 0 rgba(255,255,255,.28), 0 14px 30px rgba(62,143,255,.2); transition: all .18s ease;
}
.note-save-btn:hover { transform: translateY(-1px); box-shadow: inset 0 1px 0 rgba(255,255,255,.28), 0 18px 34px rgba(62,143,255,.24); filter: brightness(.98); }
.note-close-btn {
  font-family: 'Bangers', cursive; font-size: 16px; letter-spacing: 1.5px;
  text-transform: uppercase; border: 1px solid var(--border); background: rgba(255,255,255,.88);
  color: var(--sub); padding: 10px 22px; border-radius: 999px; cursor: pointer;
  box-shadow: var(--highlight), var(--shadow-soft); transition: all .18s ease;
  backdrop-filter: var(--glass-saturate) blur(16px);
  -webkit-backdrop-filter: var(--glass-saturate) blur(16px);
}
.note-close-btn:hover { border-color: rgba(229,57,53,.24); color: #e53935; transform: translateY(-1px); }

/* EMPTY */
.empty-msg {
  text-align: center; padding: 60px 20px;
  font-family: 'Bangers', cursive; font-size: 28px; letter-spacing: 3px;
  color: var(--muted); text-transform: uppercase;
}

/* RESPONSIVE */
@media (max-width: 900px) {
  .overview-cards,
  .sheet-stats-grid,
  .overview-split { grid-template-columns: 1fr 1fr; }
  .overview-split { gap: 14px; }
  .pt-header { grid-template-columns: 44px 30px 1fr 100px; }
  .pt-header span:nth-child(4) { display: none; }
  .p-row { grid-template-columns: 44px 30px 1fr 100px; }
  .p-row .p-topic { display: none; }
}

@media (max-width: 768px) {
  .nav { padding: 0 16px; height: 58px; gap: 10px; }
  .nav-tagline { display: none; }
  .nav-logo { font-size: 24px; letter-spacing: 2px; }

  .container { padding: 16px 12px; }

  .list-tabs { overflow-x: auto; flex-wrap: nowrap; -webkit-overflow-scrolling: touch; scroll-snap-type: x mandatory; }
  .list-tab { flex-shrink: 0; font-size: 13px; padding: 12px 10px; scroll-snap-align: start; }
  .overview-hero { grid-template-columns: 1fr; padding: 22px 18px; }
  .overview-copy h1 { font-size: 36px; }
  .overview-ring { width: 160px; }
  .overview-cards,
  .sheet-stats-grid,
  .overview-split { grid-template-columns: 1fr; }
  .overview-block-head { flex-direction: column; align-items: flex-start; }
  .overview-block-head span { text-align: left; }

  .filter-bar { gap: 8px; }
  .f-search { max-width: 100%; flex: 1 1 180px; }

  .auth-btn { font-size: 10px; padding: 5px 10px; letter-spacing: 0; }
}

@media (max-width: 540px) {
  .nav { padding: 0 12px; gap: 8px; }
  .nav-logo { font-size: 20px; }
  .nav-stats { display: none; }
  .auth-btn { max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

  .list-tab { font-size: 11px; padding: 11px 8px; letter-spacing: .5px; }
  .overview-copy h1 { font-size: 30px; }
  .overview-copy p { font-size: 13px; }
  .overview-block { padding: 18px 16px; }
  .overview-ring { width: 140px; }
  .stat-card strong,
  .sheet-stat-card strong { font-size: 26px; }
  .topic-stat-card { align-items: flex-start; }
  .topic-stat-card b { font-size: 20px; }

  .tg-header { padding: 11px 14px; gap: 10px; }
  .tg-name { font-size: 18px; }

  .pt-header { display: none; }
  .p-row { grid-template-columns: 44px 1fr auto; padding: 0 14px; min-height: 56px; }
  .p-rownum { display: none; }
  .p-topic { display: none; }
  .p-action { flex-direction: column; gap: 4px; align-items: flex-end; }
  .solve-btn { display: none; } /* title link already opens problem */
  .no-solve { display: none; }

  .filter-bar { flex-direction: column; align-items: stretch; gap: 8px; }
  .f-search { max-width: 100%; flex: 0 0 auto; }
  .f-select { width: 100%; flex: 0 0 auto; }
  .status-tabs { width: 100%; }
  .s-tab { flex: 1; text-align: center; padding: 10px 4px; }

  .progress-section { padding: 12px 14px; }
  .prog-label { font-size: 17px; }

  .signin-box { padding: 24px 18px; margin: 0 12px; min-width: 0; width: 100%; }

  .note-modal-box { padding: 18px; }
}

/* DARK THEME */
body.dark {
  --bg: #030303;
  --bg2: #0a0a0d;
  --surface: rgba(16,16,18,.76);
  --surface-strong: rgba(22,22,26,.9);
  --surface-soft: rgba(255,255,255,.06);
  --border: rgba(255,255,255,.1);
  --border-strong: rgba(255,255,255,.14);
  --accent: #7cf7ff;
  --accent2: #b78cff;
  --easy: #7dff8f;
  --green: #7dff8f;
  --text: #f5f7fb;
  --sub: rgba(245,247,251,.78);
  --muted: rgba(245,247,251,.48);
  --link: #8fe6ff;
  --shadow: 0 28px 72px rgba(0,0,0,.5);
  --shadow-soft: 0 12px 34px rgba(0,0,0,.36);
  background:
    radial-gradient(circle at 18% 18%, rgba(124,247,255,.1), transparent 22%),
    radial-gradient(circle at 82% 16%, rgba(183,140,255,.12), transparent 20%),
    radial-gradient(circle at 50% 100%, rgba(125,255,143,.08), transparent 32%),
    linear-gradient(155deg, var(--bg2), var(--bg));
}
body.dark::before {
  background:
    linear-gradient(120deg, rgba(255,255,255,.04), transparent 32%, rgba(255,255,255,.015) 60%, transparent 75%),
    radial-gradient(circle at 22% 24%, rgba(124,247,255,.05), transparent 18%),
    radial-gradient(circle at 78% 24%, rgba(183,140,255,.05), transparent 18%);
}
body.dark .nav,
body.dark .progress-section,
body.dark .ptable,
body.dark .signin-box,
body.dark .note-modal-box,
body.dark .settings-dropdown,
body.dark .f-search input,
body.dark .f-select,
body.dark .status-tabs,
body.dark .notes-btn,
body.dark .reset-btn,
body.dark .settings-gear,
body.dark .note-close-btn,
body.dark .signin-provider-btn {
  background: rgba(16,16,18,.74);
  border-color: rgba(255,255,255,.08);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.06), var(--shadow-soft);
}
body.dark .nav {
  background: rgba(10,10,12,.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}
body.dark .nav-stats,
body.dark .settings-dropdown button,
body.dark .p-rownum,
body.dark .tg-count,
body.dark .pt-header,
body.dark .s-tab,
body.dark .list-tab { color: rgba(237,245,255,.72); }
body.dark .auth-btn {
  border-color: rgba(124,247,255,.22);
  background: linear-gradient(180deg, rgba(18,33,36,.96), rgba(10,18,20,.96));
  color: var(--accent);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.06), 0 0 0 1px rgba(124,247,255,.08), 0 16px 30px rgba(0,0,0,.34);
}
body.dark .list-tabs {
  background: rgba(12,12,14,.94);
  border-color: rgba(255,255,255,.08);
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
}
body.dark .overview-hero,
body.dark .overview-block,
body.dark .sheet-stat-card,
body.dark .stat-card,
body.dark .sheet-progress-card,
body.dark .topic-stat-card {
  background: rgba(12,12,14,.96);
  border-color: rgba(255,255,255,.08);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.06), var(--shadow-soft);
}
body.dark .progress-section,
body.dark .ptable {
  background: rgba(12,12,14,.96);
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
}
body.dark .overview-ring {
  background: conic-gradient(var(--accent) calc(var(--pct) * 1%), rgba(255,255,255,.08) 0);
}
body.dark .overview-ring-inner {
  background: rgba(8,8,10,.94);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.06);
}
body.dark .list-tab { color: var(--muted); border-right-color: rgba(255,255,255,.06); }
body.dark .list-tab:hover:not(.on) { background: rgba(255,255,255,.05); color: var(--accent); }
body.dark .list-tab.on,
body.dark .s-tab.on,
body.dark .note-save-btn {
  background: linear-gradient(135deg, rgba(124,247,255,.22), rgba(183,140,255,.22));
  border-color: rgba(124,247,255,.18);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.1), 0 0 0 1px rgba(124,247,255,.08), 0 18px 34px rgba(0,0,0,.34);
}
body.dark .list-tab.on,
body.dark .s-tab.on { color: #fff; }
body.dark .f-search input::placeholder { color: var(--muted); }
body.dark .f-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath fill='%237cf7ff' d='M0 0l5 6 5-6z'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 10px center;
}
body.dark .f-select option { background: #111214; color: #edf5ff; }
body.dark .pt-header { background: rgba(255,255,255,.03); border-bottom-color: rgba(255,255,255,.07); }
body.dark .tg-header { border-bottom-color: rgba(255,255,255,.07); }
body.dark .p-row { border-bottom-color: rgba(255,255,255,.07); }
body.dark .p-row:hover { background: rgba(255,255,255,.05); }
body.dark .p-row.solved .p-name,
body.dark .p-row.solved .p-name-plain { color: rgba(237,245,255,.34); text-decoration-color: rgba(237,245,255,.18); }
body.dark .p-ext { color: rgba(237,245,255,.28); }
body.dark .p-ext:hover { color: rgba(237,245,255,.72); }
body.dark .note-textarea {
  background: rgba(8,8,10,.9);
  border-color: rgba(255,255,255,.08);
  color: var(--text);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.06), 0 12px 28px rgba(0,0,0,.2);
}
body.dark .auth-btn:hover {
  background: linear-gradient(135deg, rgba(124,247,255,.18), rgba(183,140,255,.18));
  color: #fff;
}
body.dark .auth-btn.signed-in {
  border-color: rgba(255,255,255,.08);
  color: var(--sub);
}
body.dark .auth-btn.signed-in:hover {
  background: linear-gradient(135deg, rgba(255,94,140,.26), rgba(255,168,76,.2));
  border-color: rgba(255,94,140,.18);
}
body.dark .nav-logo {
  color: #fff;
  text-shadow: 0 0 22px rgba(124,247,255,.16);
}
body.dark .nav-logo span,
body.dark .nav-stats b {
  color: var(--accent);
  text-shadow: 0 0 16px rgba(124,247,255,.18);
}
body.dark .settings-gear:hover,
body.dark .notes-btn:hover,
body.dark .p-chk:hover,
body.dark .settings-dropdown button:hover {
  color: var(--accent);
  border-color: rgba(124,247,255,.18);
}
body.dark .notes-btn.has-note {
  border-color: rgba(255,186,92,.22);
  color: #ffbe5c;
  background: rgba(38,25,10,.88);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.04), 0 10px 24px rgba(0,0,0,.3);
}
body.dark .topic-stat-card b { color: var(--accent); }
body.dark .solve-btn {
  box-shadow: inset 0 1px 0 rgba(255,255,255,.08), 0 12px 28px rgba(0,0,0,.3);
}