/* ==========================================================================
   CppPractice — Premium Design System
   Palette: deep navy / indigo / violet base with electric-blue, cyan,
   emerald, amber, coral, pink, teal accents. Dark + light themes.
   ========================================================================== */

/* ---------- Tokens ---------- */
:root {
  --c-indigo: #6366f1;
  --c-indigo-strong: #4f46e5;
  --c-violet: #8b5cf6;
  --c-blue: #3b82f6;
  --c-cyan: #22d3ee;
  --c-sky: #38bdf8;
  --c-emerald: #10b981;
  --c-teal: #14b8a6;
  --c-amber: #f59e0b;
  --c-orange: #f97316;
  --c-coral: #fb7185;
  --c-pink: #ec4899;
  --c-fuchsia: #d946ef;
  --c-rose: #f43f5e;
  --c-lime: #a3e635;

  --grad-brand: linear-gradient(135deg, #6366f1 0%, #8b5cf6 45%, #22d3ee 100%);
  --grad-brand-soft: linear-gradient(135deg, rgba(99,102,241,.18), rgba(34,211,238,.14));
  --grad-emerald: linear-gradient(135deg, #059669, #34d399);
  --grad-amber: linear-gradient(135deg, #d97706, #fbbf24);
  --grad-coral: linear-gradient(135deg, #e11d48, #fb7185);
  --grad-violet: linear-gradient(135deg, #7c3aed, #c084fc);

  --radius-xs: 8px;
  --radius-sm: 12px;
  --radius: 16px;
  --radius-lg: 22px;
  --radius-pill: 999px;

  --shadow-sm: 0 1px 2px rgba(2,6,23,.35);
  --shadow: 0 10px 30px -12px rgba(2,6,23,.55);
  --shadow-lg: 0 30px 60px -22px rgba(2,6,23,.7);
  --shadow-glow: 0 0 0 1px rgba(99,102,241,.35), 0 18px 50px -18px rgba(99,102,241,.65);

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'Fira Code', 'JetBrains Mono', 'Cascadia Code', Consolas, monospace;

  --nav-h: 68px;
  --ease: cubic-bezier(.22, 1, .36, 1);
}

/* Dark theme (default) */
:root, [data-theme="dark"] {
  --bg-0: #060a18;
  --bg-1: #0a1029;
  --bg-2: #0e1633;
  --panel: rgba(20, 27, 58, .62);
  --panel-solid: #101a3d;
  --panel-2: rgba(30, 39, 78, .5);
  --border: rgba(148, 163, 224, .16);
  --border-strong: rgba(148, 163, 224, .3);
  --text: #eef1ff;
  --text-soft: #c3cbe6;
  --muted: #8d99bd;
  --faint: #64709a;
  --input-bg: rgba(8, 13, 33, .7);
  --code-bg: #0a0f24;
  --code-line: rgba(148,163,224,.08);
  --selection: rgba(99,102,241,.35);
  --scroll-thumb: rgba(148,163,224,.28);
  color-scheme: dark;
}

/* Light theme */
[data-theme="light"] {
  --bg-0: #f4f6ff;
  --bg-1: #eef1fc;
  --bg-2: #e6ebfb;
  --panel: rgba(255, 255, 255, .82);
  --panel-solid: #ffffff;
  --panel-2: rgba(238, 242, 255, .85);
  --border: rgba(51, 65, 120, .14);
  --border-strong: rgba(51, 65, 120, .26);
  --text: #131a35;
  --text-soft: #2c3557;
  --muted: #5a6588;
  --faint: #7c87a8;
  --input-bg: rgba(255, 255, 255, .9);
  --code-bg: #f7f9ff;
  --code-line: rgba(51,65,120,.07);
  --selection: rgba(99,102,241,.22);
  --scroll-thumb: rgba(51,65,120,.28);
  --shadow: 0 10px 30px -14px rgba(30, 41, 90, .28);
  --shadow-lg: 0 28px 60px -26px rgba(30, 41, 90, .4);
  color-scheme: light;
}

/* ---------- Reset ---------- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg-0);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  min-height: 100vh;
}
h1, h2, h3, h4 { line-height: 1.2; margin: 0 0 .4em; letter-spacing: -.02em; font-weight: 800; }
p { margin: 0 0 1em; }
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font-family: inherit; font-size: inherit; color: inherit; }
code, pre, kbd { font-family: var(--font-mono); }
::selection { background: var(--selection); }
img { max-width: 100%; }

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--scroll-thumb); border-radius: 99px; border: 2px solid transparent; background-clip: content-box; }
::-webkit-scrollbar-thumb:hover { background: var(--border-strong); background-clip: content-box; }

/* ---------- Ambient background ---------- */
.bg-field {
  position: fixed; inset: 0; z-index: -2; overflow: hidden;
  background:
    radial-gradient(1100px 620px at 12% -8%, rgba(99,102,241,.22), transparent 60%),
    radial-gradient(900px 520px at 92% 4%, rgba(34,211,238,.16), transparent 60%),
    radial-gradient(900px 700px at 50% 108%, rgba(139,92,246,.16), transparent 62%),
    linear-gradient(180deg, var(--bg-0), var(--bg-1) 55%, var(--bg-0));
}
.bg-grid {
  position: fixed; inset: 0; z-index: -1; pointer-events: none; opacity: .5;
  background-image: linear-gradient(var(--code-line) 1px, transparent 1px),
                    linear-gradient(90deg, var(--code-line) 1px, transparent 1px);
  background-size: 46px 46px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 30%, #000 20%, transparent 78%);
}
.orb { position: fixed; border-radius: 50%; filter: blur(70px); opacity: .5; z-index: -1; pointer-events: none; animation: float 22s ease-in-out infinite; }
.orb-1 { width: 380px; height: 380px; background: rgba(99,102,241,.5); top: -90px; left: -60px; }
.orb-2 { width: 300px; height: 300px; background: rgba(34,211,238,.42); top: 22%; right: -80px; animation-delay: -6s; }
.orb-3 { width: 320px; height: 320px; background: rgba(168,85,247,.42); bottom: 6%; left: 18%; animation-delay: -12s; }
@keyframes float {
  0%,100% { transform: translate3d(0,0,0) scale(1); }
  50% { transform: translate3d(24px,-32px,0) scale(1.08); }
}

/* ---------- Layout ---------- */
.container { width: min(1220px, 100% - 2.4rem); margin-inline: auto; }
.app-main { min-height: calc(100vh - var(--nav-h) - 220px); padding-bottom: 4rem; }

/* ---------- Navbar ---------- */
.navbar {
  position: sticky; top: 0; z-index: 80; height: var(--nav-h);
  display: flex; align-items: center;
  background: color-mix(in srgb, var(--bg-0) 78%, transparent);
  backdrop-filter: blur(18px) saturate(1.4);
  border-bottom: 1px solid var(--border);
}
.nav-container { width: min(1400px, 100% - 2rem); margin-inline: auto; display: flex; align-items: center; gap: 1rem; }
.nav-logo { display: flex; align-items: center; gap: .6rem; font-weight: 800; font-size: 1.05rem; white-space: nowrap; }
.logo-badge {
  display: grid; place-items: center; width: 40px; height: 40px; border-radius: 12px;
  background: var(--grad-brand); color: #fff; font-family: var(--font-mono); font-weight: 700; font-size: .82rem;
  box-shadow: 0 8px 22px -8px rgba(99,102,241,.9); letter-spacing: -.5px;
}
.logo-text .dot { background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; color: transparent; }
.nav-links { display: flex; align-items: center; gap: .15rem; margin-left: auto; flex-wrap: wrap; }
.nav-link {
  padding: .5rem .8rem; border-radius: var(--radius-sm); color: var(--muted); font-weight: 600; font-size: .9rem;
  transition: color .2s, background .2s; white-space: nowrap;
}
.nav-link:hover { color: var(--text); background: var(--panel-2); }
.nav-link.active { color: var(--text); background: var(--grad-brand-soft); box-shadow: inset 0 0 0 1px var(--border-strong); }
.nav-actions { display: flex; align-items: center; gap: .5rem; }
.icon-btn {
  display: grid; place-items: center; width: 40px; height: 40px; border-radius: 12px;
  background: var(--panel); border: 1px solid var(--border); cursor: pointer; transition: transform .2s, border-color .2s, background .2s;
  font-size: 1rem;
}
.icon-btn:hover { transform: translateY(-2px); border-color: var(--border-strong); background: var(--panel-2); }
.nav-burger { display: none; }

/* ---------- Buttons ---------- */
.btn {
  --btn-bg: var(--panel); --btn-fg: var(--text); --btn-bd: var(--border);
  display: inline-flex; align-items: center; justify-content: center; gap: .5rem;
  padding: .68rem 1.15rem; border-radius: var(--radius-sm); border: 1px solid var(--btn-bd);
  background: var(--btn-bg); color: var(--btn-fg); font-weight: 650; font-size: .92rem;
  cursor: pointer; transition: transform .18s var(--ease), box-shadow .2s, background .2s, border-color .2s, opacity .2s;
  text-align: center; white-space: nowrap; user-select: none;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn:disabled { opacity: .55; cursor: not-allowed; transform: none !important; }
.btn:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, [tabindex]:focus-visible {
  outline: 2px solid var(--c-cyan); outline-offset: 2px;
}
.btn-primary { background: var(--grad-brand); color: #fff; border-color: transparent; box-shadow: 0 12px 30px -14px rgba(99,102,241,.95); }
.btn-primary:hover { box-shadow: 0 18px 40px -16px rgba(99,102,241,1); }
.btn-success { background: var(--grad-emerald); color: #04120c; border-color: transparent; box-shadow: 0 12px 30px -16px rgba(16,185,129,.9); }
.btn-danger { background: var(--grad-coral); color: #fff; border-color: transparent; }
.btn-outline { background: transparent; border-color: var(--border-strong); color: var(--text-soft); }
.btn-outline:hover { background: var(--panel-2); color: var(--text); }
.btn-ghost { background: transparent; border-color: transparent; color: var(--muted); }
.btn-ghost:hover { background: var(--panel-2); color: var(--text); }
.btn-large { padding: .9rem 1.6rem; font-size: 1rem; border-radius: var(--radius); }
.btn-small { padding: .42rem .78rem; font-size: .82rem; border-radius: var(--radius-xs); }
.btn-block { width: 100%; }

/* ---------- Cards / surfaces ---------- */
.card {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg);
  backdrop-filter: blur(14px); box-shadow: var(--shadow); position: relative;
}
.card-pad { padding: 1.4rem; }
.card-hover { transition: transform .3s var(--ease), border-color .3s, box-shadow .3s; }
.card-hover:hover { transform: translateY(-6px); border-color: var(--border-strong); box-shadow: var(--shadow-lg); }

.glass { background: var(--panel); backdrop-filter: blur(14px); border: 1px solid var(--border); }

/* ---------- Section headers ---------- */
.section { padding: 3.2rem 0; }
.section-head { margin-bottom: 1.8rem; }
.eyebrow {
  display: inline-flex; align-items: center; gap: .5rem; font-size: .74rem; font-weight: 700;
  letter-spacing: .14em; text-transform: uppercase; color: var(--c-cyan); margin-bottom: .6rem;
}
.eyebrow::before { content: ''; width: 26px; height: 2px; background: var(--grad-brand); border-radius: 2px; }
.section-title { font-size: clamp(1.5rem, 3vw, 2.15rem); }
.section-subtitle { color: var(--muted); max-width: 62ch; margin: 0; }
.gradient-text { background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* ---------- Hero ---------- */
.hero { padding: 4rem 0 2rem; position: relative; }
.hero-grid { display: grid; grid-template-columns: 1.05fr .95fr; gap: 3rem; align-items: center; }
.hero h1 { font-size: clamp(2.1rem, 5vw, 3.5rem); margin-bottom: .7rem; }
.hero .lead { font-size: clamp(1rem, 1.6vw, 1.18rem); color: var(--text-soft); max-width: 54ch; }
.hero-badge {
  display: inline-flex; align-items: center; gap: .55rem; padding: .42rem .9rem; border-radius: var(--radius-pill);
  background: var(--grad-brand-soft); border: 1px solid var(--border-strong); font-size: .82rem; font-weight: 600;
  color: var(--text-soft); margin-bottom: 1.1rem;
}
.pulse-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--c-emerald); box-shadow: 0 0 0 0 rgba(16,185,129,.6); animation: pulse 2s infinite; }
@keyframes pulse { 70% { box-shadow: 0 0 0 10px rgba(16,185,129,0); } 100% { box-shadow: 0 0 0 0 rgba(16,185,129,0); } }
.hero-buttons { display: flex; gap: .8rem; flex-wrap: wrap; margin-top: 1.5rem; }
.hero-meta { display: flex; gap: 1.6rem; margin-top: 1.8rem; flex-wrap: wrap; }
.hero-meta .m { display: flex; flex-direction: column; }
.hero-meta .m b { font-size: 1.35rem; font-weight: 800; }
.hero-meta .m span { font-size: .78rem; color: var(--muted); text-transform: uppercase; letter-spacing: .08em; }

/* 3D code card */
.hero-visual { perspective: 1400px; }
.tilt-wrap { transform-style: preserve-3d; transition: transform .35s var(--ease); }
.code-window {
  border-radius: var(--radius-lg); overflow: hidden; border: 1px solid var(--border-strong);
  background: var(--code-bg); box-shadow: var(--shadow-lg), 0 0 60px -30px rgba(99,102,241,.9);
  transform: rotateY(-11deg) rotateX(5deg);
}
.code-window-bar { display: flex; align-items: center; gap: .5rem; padding: .7rem .9rem; border-bottom: 1px solid var(--border); background: var(--panel-2); }
.dots { display: flex; gap: .4rem; }
.dot { width: 11px; height: 11px; border-radius: 50%; }
.dot.red { background: #ff5f57; } .dot.yellow { background: #febc2e; } .dot.green { background: #28c840; }
.code-window-bar .file { margin-left: .4rem; font-family: var(--font-mono); font-size: .78rem; color: var(--muted); }
.code-body { padding: 1rem 1.2rem; font-family: var(--font-mono); font-size: .84rem; line-height: 1.75; overflow-x: auto; }
.code-body .ln { white-space: pre; }
.tok-key { color: #c084fc; } .tok-fn { color: #60a5fa; } .tok-str { color: #34d399; }
.tok-num { color: #fbbf24; } .tok-com { color: #64748b; font-style: italic; } .tok-type { color: #22d3ee; }
.floating-chips { position: absolute; display: flex; gap: .5rem; }
.chip {
  padding: .38rem .72rem; border-radius: var(--radius-pill); font-size: .76rem; font-weight: 700;
  background: var(--panel-solid); border: 1px solid var(--border-strong); box-shadow: var(--shadow);
}
.chip.emerald { color: #6ee7b7; border-color: rgba(16,185,129,.5); }
.chip.amber { color: #fcd34d; border-color: rgba(245,158,11,.5); }
.chip.rose { color: #fda4af; border-color: rgba(244,63,94,.5); }
.chip.cyan { color: #67e8f9; border-color: rgba(34,211,238,.5); }

/* ---------- Stat cards ---------- */
.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 1rem; }
.stat-card { padding: 1.1rem 1.2rem; border-radius: var(--radius); background: var(--panel); border: 1px solid var(--border); transition: transform .3s var(--ease), border-color .3s; }
.stat-card:hover { transform: translateY(-4px); border-color: var(--border-strong); }
.stat-card .k { font-size: .76rem; text-transform: uppercase; letter-spacing: .09em; color: var(--muted); font-weight: 700; }
.stat-card .v { font-size: 1.7rem; font-weight: 800; margin-top: .2rem; }

/* ---------- Badges ---------- */
.badge {
  display: inline-flex; align-items: center; gap: .35rem; padding: .2rem .62rem; border-radius: var(--radius-pill);
  font-size: .74rem; font-weight: 700; letter-spacing: .02em; border: 1px solid transparent; white-space: nowrap;
}
.badge-easy { background: rgba(16,185,129,.15); color: #34d399; border-color: rgba(16,185,129,.35); }
.badge-medium { background: rgba(245,158,11,.15); color: #fbbf24; border-color: rgba(245,158,11,.35); }
.badge-hard { background: rgba(244,63,94,.15); color: #fb7185; border-color: rgba(244,63,94,.35); }
.badge-neutral { background: var(--panel-2); color: var(--muted); border-color: var(--border); }
.badge-brand { background: var(--grad-brand-soft); color: var(--text-soft); border-color: var(--border-strong); }
.badge-dot { width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
[data-theme="light"] .badge-easy { color: #047857; } [data-theme="light"] .badge-medium { color: #b45309; } [data-theme="light"] .badge-hard { color: #be123c; }

/* accent chips for category tags */
.tag { display: inline-flex; align-items: center; gap: .35rem; padding: .18rem .55rem; border-radius: var(--radius-xs); font-size: .72rem; font-weight: 650; background: var(--panel-2); border: 1px solid var(--border); color: var(--muted); }
.tag i { width: 7px; height: 7px; border-radius: 2px; display: inline-block; }

/* ---------- Forms ---------- */
.field { display: flex; flex-direction: column; gap: .4rem; }
.label { font-size: .8rem; font-weight: 650; color: var(--text-soft); }
.input, .select, .textarea {
  width: 100%; padding: .64rem .8rem; border-radius: var(--radius-sm); background: var(--input-bg);
  border: 1px solid var(--border); color: var(--text); transition: border-color .2s, box-shadow .2s;
}
.input::placeholder, .textarea::placeholder { color: var(--faint); }
.input:focus, .select:focus, .textarea:focus { border-color: var(--c-indigo); box-shadow: 0 0 0 3px rgba(99,102,241,.22); outline: none; }
.select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 18px) 52%, calc(100% - 13px) 52%; background-size: 5px 5px, 5px 5px; background-repeat: no-repeat; padding-right: 2.2rem; }
.textarea { font-family: var(--font-mono); resize: vertical; }
.search-wrap { position: relative; flex: 1; min-width: 220px; }
.search-wrap .search-icon { position: absolute; left: .8rem; top: 50%; transform: translateY(-50%); color: var(--faint); pointer-events: none; }
.search-wrap .input { padding-left: 2.3rem; }

.toolbar { display: flex; gap: .7rem; flex-wrap: wrap; align-items: center; }
.seg { display: inline-flex; padding: .25rem; gap: .2rem; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-pill); }
.seg button { padding: .38rem .8rem; border-radius: var(--radius-pill); border: none; background: transparent; color: var(--muted); font-weight: 650; font-size: .82rem; cursor: pointer; transition: .2s; }
.seg button.active { background: var(--grad-brand); color: #fff; }
.seg button:hover:not(.active) { color: var(--text); }

/* ---------- Problem list ---------- */
.problem-list { display: flex; flex-direction: column; gap: .55rem; }
.problem-row {
  display: grid; grid-template-columns: 74px 1fr auto; gap: 1rem; align-items: center;
  padding: .85rem 1.1rem; border-radius: var(--radius); background: var(--panel); border: 1px solid var(--border);
  cursor: pointer; transition: transform .2s var(--ease), border-color .2s, background .2s, box-shadow .2s; text-decoration: none;
}
.problem-row:hover { transform: translateX(5px); border-color: var(--border-strong); box-shadow: var(--shadow); background: var(--panel-2); }
.problem-row .pid { font-family: var(--font-mono); font-size: .82rem; color: var(--muted); font-weight: 600; }
.problem-row .ptitle { font-weight: 650; color: var(--text); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.problem-row .pmeta { display: flex; align-items: center; gap: .5rem; flex-wrap: wrap; justify-content: flex-end; }
.problem-row.is-solved { border-left: 3px solid var(--c-emerald); }
.problem-row.is-solved .pid::before { content: '✓ '; color: var(--c-emerald); }
.problem-row.is-bookmarked { border-right: 3px solid var(--c-amber); }

.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(270px, 1fr)); gap: 1rem; }
.problem-card {
  padding: 1.1rem; border-radius: var(--radius); background: var(--panel); border: 1px solid var(--border);
  cursor: pointer; transition: transform .3s var(--ease), border-color .3s, box-shadow .3s; position: relative; overflow: hidden;
}
.problem-card::after { content: ''; position: absolute; inset: 0 auto 0 0; width: 3px; background: var(--grad-brand); opacity: 0; transition: opacity .3s; }
.problem-card:hover { transform: translateY(-6px); border-color: var(--border-strong); box-shadow: var(--shadow-lg); }
.problem-card:hover::after { opacity: 1; }
.problem-card h3 { font-size: 1rem; margin: .5rem 0 .4rem; }
.problem-card .excerpt { color: var(--muted); font-size: .85rem; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; margin-bottom: .8rem; }
.problem-card .foot { display: flex; align-items: center; justify-content: space-between; gap: .5rem; }
.problem-card.is-solved { border-color: rgba(16,185,129,.45); }

/* ---------- Pagination ---------- */
.pagination { display: flex; align-items: center; justify-content: center; gap: .35rem; flex-wrap: wrap; margin-top: 1.6rem; }
.page-btn { min-width: 38px; height: 38px; padding: 0 .6rem; border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--panel); color: var(--text-soft); font-weight: 650; cursor: pointer; transition: .2s; }
.page-btn:hover:not(:disabled) { border-color: var(--border-strong); background: var(--panel-2); color: var(--text); }
.page-btn.active { background: var(--grad-brand); color: #fff; border-color: transparent; }
.page-btn:disabled { opacity: .4; cursor: not-allowed; }
.page-info { color: var(--muted); font-size: .85rem; margin: 0 .5rem; }

/* ---------- Workspace (problem page) ---------- */
.workspace { display: grid; gap: 1rem; grid-template-columns: minmax(320px, 1.05fr) minmax(360px, 1.25fr) minmax(320px, 1.05fr); align-items: start; }
.panel { border-radius: var(--radius-lg); border: 1px solid var(--border); background: var(--panel); backdrop-filter: blur(14px); box-shadow: var(--shadow); display: flex; flex-direction: column; overflow: hidden; }
.panel-head { display: flex; align-items: center; gap: .6rem; padding: .8rem 1rem; border-bottom: 1px solid var(--border); background: var(--panel-2); }
.panel-head .title { font-weight: 700; font-size: .92rem; display: flex; align-items: center; gap: .45rem; }
.panel-head .spacer { margin-left: auto; }
.panel-body { padding: 1rem 1.1rem; overflow: auto; }

.statement-panel .panel-body { max-height: calc(100vh - var(--nav-h) - 130px); }
.statement h1 { font-size: 1.35rem; margin: .3rem 0 .5rem; }
.stmt-block { margin: 1rem 0; }
.stmt-block h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .1em; color: var(--c-cyan); margin-bottom: .35rem; }
.stmt-block p { color: var(--text-soft); margin: 0; }
.io-grid { display: grid; grid-template-columns: 1fr 1fr; gap: .8rem; }
.sample-box { border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--code-bg); overflow: hidden; }
.sample-box .sb-head { display: flex; align-items: center; gap: .5rem; padding: .45rem .7rem; border-bottom: 1px solid var(--border); font-size: .74rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.sample-box .sb-head .spacer { margin-left: auto; }
.sample-box pre { margin: 0; padding: .7rem .8rem; font-size: .84rem; white-space: pre-wrap; word-break: break-word; color: var(--text-soft); max-height: 220px; overflow: auto; }
.copy-mini { border: 1px solid var(--border); background: var(--panel); color: var(--muted); border-radius: 6px; padding: .18rem .45rem; font-size: .7rem; cursor: pointer; font-weight: 650; }
.copy-mini:hover { color: var(--text); border-color: var(--border-strong); }

.exec-panel .run-error { color: var(--c-coral); }
.run-bar { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; padding: .9rem 1.1rem; border-bottom: 1px solid var(--border); }
.run-bar .grow { flex: 1; }

.status-pill { display: inline-flex; align-items: center; gap: .45rem; padding: .3rem .7rem; border-radius: var(--radius-pill); font-size: .78rem; font-weight: 700; border: 1px solid var(--border); background: var(--panel-2); color: var(--muted); }
.status-pill.idle { color: var(--muted); }
.status-pill.queued, .status-pill.compiling, .status-pill.running { color: #67e8f9; border-color: rgba(34,211,238,.4); background: rgba(34,211,238,.1); }
.status-pill.accepted { color: #34d399; border-color: rgba(16,185,129,.45); background: rgba(16,185,129,.1); }
.status-pill.wrong_answer, .status-pill.runtime_error, .status-pill.compilation_error, .status-pill.time_limit_exceeded, .status-pill.internal_error { color: #fb7185; border-color: rgba(244,63,94,.45); background: rgba(244,63,94,.1); }
.status-pill .spin { width: 12px; height: 12px; border-radius: 50%; border: 2px solid currentColor; border-right-color: transparent; animation: spin .7s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

.console-tabs { display: flex; gap: .2rem; padding: .5rem .7rem 0; border-bottom: 1px solid var(--border); }
.console-tab { padding: .45rem .85rem; border: none; background: transparent; color: var(--muted); font-weight: 650; font-size: .82rem; cursor: pointer; border-bottom: 2px solid transparent; border-radius: 6px 6px 0 0; }
.console-tab.active { color: var(--text); border-bottom-color: var(--c-indigo); background: var(--panel-2); }
.console-tab .dotmark { display: inline-block; width: 6px; height: 6px; border-radius: 50%; margin-left: .35rem; background: var(--c-coral); }
.console {
  font-family: var(--font-mono); font-size: .84rem; line-height: 1.65; padding: .85rem 1rem;
  min-height: 130px; max-height: 260px; overflow: auto; white-space: pre-wrap; word-break: break-word;
  background: var(--code-bg); color: var(--text-soft); margin: 0;
}
.console.err { color: #fda4af; }
.console.empty { color: var(--faint); font-style: italic; }
.metric-row { display: flex; gap: 1.2rem; flex-wrap: wrap; padding: .6rem 1.1rem; border-top: 1px solid var(--border); font-size: .8rem; color: var(--muted); }
.metric-row b { color: var(--text-soft); font-family: var(--font-mono); font-weight: 650; }

.test-results { display: flex; flex-direction: column; gap: .4rem; padding: .7rem 1.1rem; }
.test-item { display: flex; align-items: center; gap: .6rem; font-size: .84rem; padding: .4rem .6rem; border-radius: var(--radius-xs); background: var(--panel-2); border: 1px solid var(--border); }
.test-item .mark { width: 20px; height: 20px; border-radius: 50%; display: grid; place-items: center; font-size: .7rem; font-weight: 800; color: #04120c; }
.test-item.pass .mark { background: var(--c-emerald); }
.test-item.fail .mark { background: var(--c-coral); color: #fff; }
.test-item.skip .mark { background: var(--c-amber); }
.test-item .tname { flex: 1; }
.test-item .tnote { color: var(--muted); font-size: .78rem; }

.io-field { padding: .7rem 1.1rem; border-top: 1px solid var(--border); }
.io-field .head { display: flex; align-items: center; gap: .5rem; margin-bottom: .4rem; }
.io-field .head .t { font-size: .78rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.io-field textarea { width: 100%; min-height: 72px; font-family: var(--font-mono); font-size: .84rem; background: var(--code-bg); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: .6rem .7rem; color: var(--text); resize: vertical; }
.io-field textarea:focus { outline: none; border-color: var(--c-indigo); box-shadow: 0 0 0 3px rgba(99,102,241,.2); }

/* editor panel */
.editor-panel .editor-shell { flex: 1; min-height: 340px; display: flex; flex-direction: column; }
.monaco-host { flex: 1; min-height: 340px; width: 100%; }
.editor-fallback { flex: 1; width: 100%; min-height: 340px; border: none; background: var(--code-bg); color: var(--text); font-family: var(--font-mono); font-size: 14px; line-height: 1.6; padding: .8rem 1rem; resize: none; outline: none; tab-size: 4; }
.editor-toolbar { display: flex; align-items: center; gap: .4rem; padding: .5rem .7rem; border-bottom: 1px solid var(--border); flex-wrap: wrap; }
.editor-toolbar .grow { flex: 1; }
.mini-btn { border: 1px solid var(--border); background: var(--panel); color: var(--muted); border-radius: var(--radius-xs); padding: .32rem .55rem; font-size: .76rem; font-weight: 650; cursor: pointer; transition: .18s; display: inline-flex; align-items: center; gap: .3rem; }
.mini-btn:hover { color: var(--text); border-color: var(--border-strong); background: var(--panel-2); }
.mini-btn.danger:hover { color: #fb7185; border-color: rgba(244,63,94,.5); }

/* resizer */
.resizer { width: 10px; cursor: col-resize; align-self: stretch; display: flex; align-items: center; justify-content: center; }
.resizer::before { content: ''; width: 3px; height: 46px; border-radius: 3px; background: var(--border); transition: background .2s; }
.resizer:hover::before, .resizer.dragging::before { background: var(--c-indigo); }

.problem-nav { display: flex; align-items: center; gap: .6rem; justify-content: space-between; }
.problem-nav .pn-btn { flex: 1; }
.pn-label { text-align: center; font-size: .78rem; color: var(--muted); font-family: var(--font-mono); }

/* mobile tabs for workspace */
.mobile-tabs { display: none; gap: .3rem; padding: .3rem; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-pill); margin-bottom: .8rem; }
.mobile-tabs button { flex: 1; padding: .5rem; border-radius: var(--radius-pill); border: none; background: transparent; color: var(--muted); font-weight: 650; cursor: pointer; }
.mobile-tabs button.active { background: var(--grad-brand); color: #fff; }

/* ---------- Progress ---------- */
.progress-hero { display: grid; grid-template-columns: auto 1fr; gap: 2rem; align-items: center; }
.ring-wrap { position: relative; width: 168px; height: 168px; }
.ring-wrap svg { transform: rotate(-90deg); }
.ring-bg { fill: none; stroke: var(--panel-2); stroke-width: 12; }
.ring-fill { fill: none; stroke: url(#ringGrad); stroke-width: 12; stroke-linecap: round; transition: stroke-dashoffset .9s var(--ease); }
.ring-center { position: absolute; inset: 0; display: grid; place-items: center; text-align: center; }
.ring-center .big { font-size: 2rem; font-weight: 800; }
.ring-center .sub { font-size: .74rem; color: var(--muted); text-transform: uppercase; letter-spacing: .08em; }
.meter { height: 10px; border-radius: 99px; background: var(--panel-2); overflow: hidden; }
.meter > span { display: block; height: 100%; border-radius: 99px; background: var(--grad-brand); transition: width .8s var(--ease); }
.meter.easy > span { background: var(--grad-emerald); }
.meter.medium > span { background: var(--grad-amber); }
.meter.hard > span { background: var(--grad-coral); }

.bar-track { display: grid; gap: .7rem; }
.bar-row { display: grid; grid-template-columns: 150px 1fr auto; gap: .8rem; align-items: center; }
.bar-row .bl { font-size: .84rem; color: var(--text-soft); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.bar-row .bv { font-family: var(--font-mono); font-size: .82rem; color: var(--muted); }

/* ---------- Tables ---------- */
.table { width: 100%; border-collapse: collapse; font-size: .88rem; }
.table th { text-align: left; padding: .6rem .7rem; color: var(--muted); font-size: .74rem; text-transform: uppercase; letter-spacing: .08em; border-bottom: 1px solid var(--border); }
.table td { padding: .6rem .7rem; border-bottom: 1px solid var(--border); color: var(--text-soft); }
.table tr:hover td { background: var(--panel-2); }
/* Horizontally scrollable wrapper for wide tables (privacy policy keys) */
.table-wrap { overflow-x: auto; }
.table-wrap .table { min-width: 460px; }

/* ---------- Toast ---------- */
.toast-stack { position: fixed; right: 1.1rem; bottom: 1.1rem; z-index: 200; display: flex; flex-direction: column; gap: .6rem; max-width: min(360px, 90vw); }
.toast {
  display: flex; gap: .65rem; align-items: flex-start; padding: .8rem .95rem; border-radius: var(--radius);
  background: var(--panel-solid); border: 1px solid var(--border-strong); box-shadow: var(--shadow-lg);
  animation: toastIn .3s var(--ease); font-size: .88rem;
}
.toast.leaving { animation: toastOut .25s var(--ease) forwards; }
.toast .ico { font-size: 1.05rem; line-height: 1.3; }
.toast.success { border-left: 3px solid var(--c-emerald); }
.toast.error { border-left: 3px solid var(--c-coral); }
.toast.info { border-left: 3px solid var(--c-cyan); }
.toast.warn { border-left: 3px solid var(--c-amber); }
@keyframes toastIn { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: none; } }
@keyframes toastOut { to { opacity: 0; transform: translateX(30px); } }

/* ---------- Loading / empty ---------- */
.skeleton { background: linear-gradient(90deg, var(--panel-2) 25%, var(--border) 37%, var(--panel-2) 63%); background-size: 400% 100%; animation: shimmer 1.4s ease infinite; border-radius: var(--radius-sm); }
@keyframes shimmer { 0% { background-position: 100% 0; } 100% { background-position: -100% 0; } }
.spinner { width: 34px; height: 34px; border-radius: 50%; border: 3px solid var(--border); border-top-color: var(--c-indigo); animation: spin .8s linear infinite; }
.center-box { display: grid; place-items: center; padding: 3rem 1rem; text-align: center; gap: 1rem; }
.empty-state { display: grid; place-items: center; gap: .6rem; padding: 3rem 1rem; text-align: center; color: var(--muted); }
.empty-state .emoji { font-size: 2.6rem; }
.empty-state h3 { color: var(--text); margin: 0; }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--border); background: color-mix(in srgb, var(--bg-0) 70%, transparent); padding: 2.4rem 0 1.6rem; margin-top: 3rem; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 1.6rem; }
.footer h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .1em; color: var(--muted); margin-bottom: .7rem; }
.footer a { display: block; color: var(--text-soft); font-size: .88rem; padding: .18rem 0; transition: color .2s; }
.footer a:hover { color: var(--c-cyan); }
.footer-bottom { display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap; margin-top: 1.8rem; padding-top: 1.1rem; border-top: 1px solid var(--border); color: var(--faint); font-size: .82rem; }

/* ---------- Utilities ---------- */
.row { display: flex; gap: .7rem; align-items: center; flex-wrap: wrap; }
.between { display: flex; gap: .7rem; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1rem; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 1rem; }
.mt-1 { margin-top: .5rem; } .mt-2 { margin-top: 1rem; } .mt-3 { margin-top: 1.6rem; }
.mb-0 { margin-bottom: 0; } .mb-1 { margin-bottom: .5rem; } .mb-2 { margin-bottom: 1rem; } .mb-3 { margin-bottom: 1.6rem; }
.muted { color: var(--muted); } .small { font-size: .82rem; } .mono { font-family: var(--font-mono); }
.hidden { display: none !important; }
.divider { height: 1px; background: var(--border); margin: 1.2rem 0; border: 0; }
kbd { background: var(--panel-2); border: 1px solid var(--border-strong); border-bottom-width: 2px; border-radius: 6px; padding: .1rem .4rem; font-size: .78rem; }
.pill-list { display: flex; gap: .4rem; flex-wrap: wrap; }
.anchor-offset { scroll-margin-top: calc(var(--nav-h) + 16px); }
.hero-code-note { font-size: .8rem; color: var(--muted); margin-top: .8rem; }

/* reveal on scroll */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s var(--ease), transform .6s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 1180px) {
  .workspace { grid-template-columns: 1fr 1fr; }
  .workspace .editor-panel { grid-column: 1 / -1; }
}
@media (max-width: 960px) {
  .hero-grid { grid-template-columns: 1fr; gap: 2rem; }
  .hero-visual { max-width: 520px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .progress-hero { grid-template-columns: 1fr; justify-items: center; text-align: center; }
}
@media (max-width: 820px) {
  .nav-burger { display: grid; }
  .nav-links {
    position: absolute; top: var(--nav-h); left: 0; right: 0; flex-direction: column; align-items: stretch;
    background: var(--panel-solid); border-bottom: 1px solid var(--border); padding: .6rem; gap: .2rem;
    transform: translateY(-12px); opacity: 0; pointer-events: none; transition: .25s var(--ease); margin-left: 0;
  }
  .nav-links.open { transform: none; opacity: 1; pointer-events: auto; }
  .workspace { grid-template-columns: 1fr; }
  .mobile-tabs { display: flex; }
  .workspace[data-mobile="statement"] .exec-panel,
  .workspace[data-mobile="statement"] .editor-panel { display: none; }
  .workspace[data-mobile="run"] .statement-panel,
  .workspace[data-mobile="run"] .editor-panel { display: none; }
  .workspace[data-mobile="code"] .statement-panel,
  .workspace[data-mobile="code"] .exec-panel { display: none; }
  .statement-panel .panel-body { max-height: none; }
  .problem-row { grid-template-columns: 60px 1fr; }
  .problem-row .pmeta { grid-column: 2; justify-content: flex-start; }
  .bar-row { grid-template-columns: 110px 1fr auto; }
  .io-grid { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .container { width: calc(100% - 1.6rem); }
  .card-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-meta { gap: 1.1rem; }
  .section { padding: 2.2rem 0; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; transition-duration: .001ms !important; scroll-behavior: auto !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ==========================================================================
   Advertising (opt-in — see js/ads.js)
   Nothing here is visible unless a publisher id is configured *and* the visitor
   accepted advertising cookies, because js/core.js then emits no markup at all.
   ========================================================================== */
.ad-section { padding-top: .5rem; }

.ad-slot {
  display: block;
  margin: 0 auto;
  max-width: 970px;
  /* Reserve room so a filling unit cannot shove the page around. */
  min-height: 120px;
  padding: .7rem .8rem .9rem;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: var(--panel-2);
  text-align: center;
}

.ad-label {
  display: block;
  margin-bottom: .45rem;
  font-size: .62rem;
  font-weight: 700;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--faint);
}

.ad-slot ins.adsbygoogle { display: block; }

/* ==========================================================================
   Advertising consent card — only rendered when ads are configured
   ========================================================================== */
#consentHost {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 400;
  padding: .8rem;
  pointer-events: none;
}
#consentHost[hidden] { display: none; }

.consent-card {
  pointer-events: auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: .9rem 1.2rem;
  max-width: 1000px;
  margin: 0 auto;
  padding: .95rem 1.1rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  background: var(--panel-solid);
  box-shadow: var(--shadow-lg);
}

.consent-text { flex: 1 1 26rem; min-width: 0; }
.consent-text strong { display: block; margin-bottom: .25rem; }
.consent-actions { display: flex; flex-wrap: wrap; gap: .5rem; }

@media (max-width: 560px) {
  .consent-card { padding: .85rem; }
  .consent-actions { width: 100%; }
  .consent-actions .btn { flex: 1 1 auto; }
}