* { box-sizing: border-box; }

/* =========================
   Theme variables
   ========================= */
:root{
  /* Light theme */
  --bg: #ffffff;
  --text: #111111;
  --muted: #5b6472;

  --panel: #ffffff;

  --border: #e3e6ea;
  --border-strong: #c7cfe0;

  --link: #2c4b8a;

  --btn-bg: #111827;
  --btn-text: #ffffff;
  --btn-border: #111827;

  --btn-secondary-bg: transparent;
  --btn-secondary-text: #111827;

  /* Default code style (used in lectures) */
  --code-bg: #f3f4f6;
  --code-text: #1f2328;

  --thead-bg: #fafafa;
  --table-border: #ececec;

  --alert-bg: #fff3f3;
  --alert-border: #ffd0d0;
  --alert-text: #8a1f1f;

  --flash-bg: #f7f7f7;
  --flash-border: #e0e0e0;

  --flash-info-bg: #eef6ff;
  --flash-info-border: #cfe6ff;

  --flash-ok-bg: #eefbf1;
  --flash-ok-border: #c9f2d2;

  --flash-bad-bg: #fff3f3;
  --flash-bad-border: #ffd0d0;

  --shadow-card: 0 2px 6px rgba(0,0,0,0.05);
}

:root[data-theme="dark"]{
  /* Global dark (lectures already look good with this) */
  --bg: #0b0f16;
  --text: #e8eefc;
  --muted: #a7b0c3;

  --panel: #121826;

  --border: #273044;
  --border-strong: #3a4661;

  --link: #c8d2ea;

  --btn-bg: #e8eefc;
  --btn-text: #0b0f16;
  --btn-border: #3a4661;

  --btn-secondary-bg: transparent;
  --btn-secondary-text: #e8eefc;

  --code-bg: #0d1117;
  --code-text: #e6edf3;

  --thead-bg: #0f1523;
  --table-border: #232c40;

  --alert-bg: #2a0f15;
  --alert-border: #5a2430;
  --alert-text: #ffd0d0;

  --flash-bg: #0f1523;
  --flash-border: #273044;

  --flash-info-bg: #0b1a2a;
  --flash-info-border: #204462;

  --flash-ok-bg: #0b2414;
  --flash-ok-border: #1e4b2a;

  --flash-bad-bg: #2a0f15;
  --flash-bad-border: #5a2430;

  --shadow-card: 0 4px 14px rgba(0,0,0,0.55);
}

/* =========================
   Base layout
   ========================= */
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  line-height: 1.4;
  background: var(--bg);
  color: var(--text);
}

/* Keep your dark background vibe globally (lectures OK) */
:root[data-theme="dark"] body {
  background:
    radial-gradient(1200px 600px at 25% -10%, rgba(88, 166, 255, 0.10), transparent 60%),
    radial-gradient(900px 500px at 85% 0%, rgba(163, 113, 247, 0.08), transparent 55%),
    var(--bg);
}

a { color: inherit; text-decoration: none; }

.container { max-width: 980px; margin: 0 auto; padding: 16px; }

.header {
  border-bottom: 1px solid var(--border);
  background: var(--panel);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header__inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.logo { font-weight: 700; }

.nav a { margin-left: 12px; color: var(--link); }
.nav a:hover { text-decoration: underline; }

.footer {
  border-top: 1px solid var(--border);
  margin-top: 32px;
  padding: 16px 0;
  color: var(--muted);
}

.muted { color: var(--muted); }

/* =========================
   Page header (title + filter)
   ========================= */
.page-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin: 8px 0 10px;
}

.page-title { margin: 0; font-size: 40px; letter-spacing: -0.5px; }
.page-subtitle { margin: 8px 0 0; max-width: 680px; }
.btn-link { color: var(--link); text-decoration: underline; font-size: 14px; }

/* =========================
   Filter + tasks list
   ========================= */
.filter {
  margin: 12px 0 16px;
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
}

.filter select {
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
}

.task-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

/* Card */
.task-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

.task-card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(0,0,0,0.15);
}

.task-card__top { display: flex; align-items: start; justify-content: space-between; gap: 10px; }
.task-card__title { margin: 0; font-size: 18px; color: var(--text); }
.task-card__desc { margin: 10px 0 0; color: var(--muted); }

/* Task page header row */
.task-header { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }

/* Row of small pills (e.g. level + solved/attempted) */
.badge-row { display: inline-flex; gap: 8px; align-items: center; flex-wrap: wrap; justify-content: flex-end; }

/* =========================
   Difficulty badge (FIX: different colors)
   ========================= */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  font-size: 12px;
  color: var(--text);
  background: rgba(127,127,127,0.10);
  white-space: nowrap;
}

.badge::before{
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: var(--border-strong);
}

/* Level colors by class from task.html */
.badge-easy    { border-color: rgba(46, 160, 67, 0.35); background: rgba(46, 160, 67, 0.10); }
.badge-easy::before { background: #2ea043; }

.badge-medium  { border-color: rgba(245, 158, 11, 0.45); background: rgba(245, 158, 11, 0.14); }
.badge-medium::before { background: #f59e0b; }

.badge-hard    { border-color: rgba(248, 81, 73, 0.35); background: rgba(248, 81, 73, 0.10); }
.badge-hard::before { background: #f85149; }

.badge-advanced { border-color: rgba(163, 113, 247, 0.35); background: rgba(163, 113, 247, 0.10); }
.badge-advanced::before { background: #a371f7; }

/* Status badges */
.badge-solved { border-color: rgba(46, 160, 67, 0.55); background: rgba(46, 160, 67, 0.18); }
.badge-solved::before { background: #2ea043; }

.badge-attempted { border-color: rgba(245, 158, 11, 0.55); background: rgba(245, 158, 11, 0.18); }
.badge-attempted::before { background: #f59e0b; }

/* =========================
   Code / SQL input
   ========================= */
/* Default .code used everywhere */
.code {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 12px 14px;
  border-radius: 10px;
  overflow: auto;
  border: 1px solid var(--border);
  font-size: 14px;
  line-height: 1.55;
}

/* ✅ Task page: restore "black" SQL block in LIGHT theme only */
:root:not([data-theme="dark"]) .task-header ~ .code,
:root:not([data-theme="dark"]) .task-header ~ h3 + .code,
:root:not([data-theme="dark"]) .task-header ~ pre.code {
  background: #0f172a;   /* near-black */
  color: #e5e7eb;
  border-color: #0f172a;
}

/* Ensure inline spacing for code blocks on tasks */
.task-header ~ pre.code { margin: 10px 0 18px; }

/* SQL form */
.sql-form textarea {
  width: 100%;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  padding: 10px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
}

/* =========================
   Less aggressive dark theme for TASKS ONLY
   (lectures untouched)
   ========================= */
/* We detect task page by presence of .task-header and adjust nearby blocks */
:root[data-theme="dark"] .task-header ~ p,
:root[data-theme="dark"] .task-header ~ h3,
:root[data-theme="dark"] .task-header ~ .muted {
  color: var(--text);
}

/* Softer panels around task inputs/results (without changing lecture blocks) */
:root[data-theme="dark"] .task-header ~ pre.code,
:root[data-theme="dark"] .task-header ~ .sql-form textarea,
:root[data-theme="dark"] .task-header ~ .table-wrap {
  background: #121a2a;                /* softer than near-black */
  border-color: rgba(255,255,255,0.12);
}

/* Code blocks on tasks in dark: slightly lighter + less contrast */
:root[data-theme="dark"] .task-header ~ pre.code {
  color: #d7deea;
}

/* Textarea in tasks dark: calm */
:root[data-theme="dark"] .task-header ~ .sql-form textarea {
  background: #111a29;
  color: #e8eefc;
}

/* Table wrap in tasks dark */
.table-wrap {
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--panel);
}

:root[data-theme="dark"] .task-header ~ .table-wrap {
  background: #121a2a;
}

/* A bit less heavy shadow on task page elements (softer look) */
:root[data-theme="dark"] .task-header ~ pre.code,
:root[data-theme="dark"] .task-header ~ .table-wrap,
:root[data-theme="dark"] .task-header ~ .sql-form textarea {
  box-shadow: 0 10px 26px rgba(0,0,0,0.28);
}

/* Form actions */
.form-actions { display: flex; gap: 10px; margin-top: 10px; flex-wrap: wrap; }

button {
  padding: 9px 12px;
  border: 1px solid var(--btn-border);
  border-radius: 10px;
  background: var(--btn-bg);
  color: var(--btn-text);
  cursor: pointer;
}

button.secondary {
  background: transparent;
  color: var(--btn-secondary-text);
  border-color: var(--btn-border);
}

button:hover { opacity: 0.92; }

/* =========================
   Landing blocks (homepage)
   ========================= */
.btn{
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 14px;
  border: 1px solid var(--btn-border);
  border-radius: 12px;
  background: var(--btn-bg);
  color: var(--btn-text);
  cursor: pointer;
  font-weight: 600;
}

.btn.secondary{
  background: transparent;
  color: var(--btn-secondary-text);
  border-color: var(--btn-border);
}

.btn:hover{ opacity: 0.92; }

.hero{
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  padding: 22px;
  margin: 14px 0 18px;
}

.hero__inner{ max-width: 820px; }

.hero__title{
  margin: 0;
  font-size: 42px;
  letter-spacing: -0.6px;
  line-height: 1.12;
}

.hero__subtitle{ margin: 12px 0 0; color: var(--muted); font-size: 16px; }

.hero__benefits{
  margin: 14px 0 0;
  padding-left: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  color: var(--text);
  list-style: none;
}

.hero__cta{ margin-top: 16px; display: flex; gap: 10px; flex-wrap: wrap; }

.hero__try{
  display: inline-block;
  margin-top: 14px;
  color: var(--link);
  text-decoration: underline;
  font-size: 14px;
}

.section{ margin: 22px 0; }
.section__title{ margin: 0 0 10px; font-size: 24px; }
.section__note{ margin: 10px 0 0; }

.seg-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
}

.seg-card{
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  padding: 14px;
  transition: transform 0.15s ease, border-color 0.15s ease;
}

.seg-card:hover{ border-color: var(--border-strong); transform: translateY(-1px); }
.seg-card__title{ font-weight: 700; }
.seg-card__desc{ color: var(--muted); margin-top: 6px; }

.how-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
}

.how-card{
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  padding: 14px;
  display: flex;
  gap: 12px;
}

.how-card__num{ font-size: 18px; }
.how-card__title{ font-weight: 700; }
.how-card__desc{ color: var(--muted); margin-top: 4px; }

.rec-list{ display: grid; gap: 10px; margin: 10px 0 14px; }

.rec-item{
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  padding: 12px 14px;
  display: flex;
  gap: 10px;
  align-items: center;
}

.rec-item:hover{ border-color: var(--border-strong); }
.rec-item__title{ font-weight: 700; }
.rec-item__arrow{ margin-left: auto; color: var(--muted); }

.checks{
  margin: 8px 0 0;
  padding-left: 0;
  display: grid;
  gap: 6px;
  list-style: none;
}

.final-cta{
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--panel);
  box-shadow: var(--shadow-card);
  padding: 18px;
  margin: 26px 0 10px;
}

.final-cta__title{ margin: 0 0 8px; }

@media (max-width: 560px){
  .hero{ padding: 18px; }
  .hero__title{ font-size: 32px; }
}

/* =========================
   Alerts / flash messages
   ========================= */
.alert {
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--alert-bg);
  border: 1px solid var(--alert-border);
  color: var(--alert-text);
}

.flash-list { margin: 10px 0; display: grid; gap: 8px; }

.flash {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--flash-border);
  background: var(--flash-bg);
  color: var(--text);
}

.flash--info { border-color: var(--flash-info-border); background: var(--flash-info-bg); }
.flash--ok   { border-color: var(--flash-ok-border);   background: var(--flash-ok-bg); }
.flash--bad  { border-color: var(--flash-bad-border);  background: var(--flash-bad-bg); }

/* =========================
   Tables (general)
   ========================= */
table { width: 100%; border-collapse: collapse; }

th, td {
  padding: 10px;
  border-bottom: 1px solid var(--table-border);
  text-align: left;
  font-size: 14px;
  color: var(--text);
}

thead th {
  background: var(--thead-bg);
  border-bottom: 1px solid var(--table-border);
}

/* =========================
   Lectures (do not "redesign" here)
   Keep stable / readable as you said OK
   ========================= */
.lecture { max-width: 900px; }
.lecture h1, .lecture h2, .lecture h3 { color: var(--text); }
.lecture p, .lecture li { color: var(--text); line-height: 1.65; }
.lecture hr { border: 0; border-top: 1px solid var(--border); margin: 22px 0; }

pre.sql {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 12px 14px;
  border-radius: 10px;
  overflow-x: auto;
  font-size: 14px;
  line-height: 1.55;
  margin: 14px 0;
  border: 1px solid var(--border);
}

pre.sql code {
  background: transparent;
  border: 0;
  padding: 0;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  white-space: pre;
}

/* Result block used in some lecture templates */
.result { margin: 10px 0 18px; }
.result__title { font-size: 13px; color: var(--muted); margin: 8px 0 6px; }
.result table {
  width: 100%;
  border-collapse: collapse;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
}

.result th, .result td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--table-border);
}

/* =========================
   Theme toggle button
   ========================= */
.theme-toggle{
  margin-left: 12px;
  padding: 6px 10px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  cursor: pointer;
}
.theme-toggle:hover{ opacity: 0.9; }


/* =========================
   Auth forms / header user
   ========================= */
.auth-form {
  max-width: 520px;
  margin: 18px 0;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
}

.form-row { display: flex; flex-direction: column; gap: 6px; margin-bottom: 12px; }

.auth-form label { font-weight: 600; }

.auth-form input[type="text"],
.auth-form input[type="email"],
.auth-form input[type="password"] {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
}

.nav-user { color: var(--muted); margin-left: 10px; }
.nav-logout { display: inline; margin: 0 0 0 8px; }
.nav-logout button { padding: 6px 10px; border-radius: 10px; }


/* Progress UI */
.nav-progress{
  margin-left: 10px;
  font-size: 0.9rem;
  opacity: 0.9;
}

.progress-bar{
  width: 100%;
  height: 10px;
  border-radius: 999px;
  background: rgba(0,0,0,0.08);
  overflow: hidden;
  margin: 10px 0 16px;
}
[data-theme="dark"] .progress-bar{
  background: rgba(255,255,255,0.12);
}
.progress-bar__fill{
  height: 100%;
  background: rgba(0,0,0,0.35);
}
[data-theme="dark"] .progress-bar__fill{
  background: rgba(255,255,255,0.35);
}

/* Anchor offset for sticky header */
:root{ --anchor-offset: 88px; }
.section{ scroll-margin-top: var(--anchor-offset); }

/* Slightly smaller sticky header on mobile */
@media (max-width: 768px){
  :root{ --anchor-offset: 64px; }
}