:root {
  --bg: #161824;
  --bg-elevated: #1e2032;
  --bg-hover: rgba(247, 85, 85, 0.1);
  --border: #282c48;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --accent: #f75555;
  --accent-dim: rgba(247, 85, 85, 0.12);
  --accent-soft: rgba(247, 85, 85, 0.05);
  --accent-glow: rgba(247, 85, 85, 0.35);
  --success: #4ade80;
  --success-bg: rgba(74, 222, 128, 0.12);
  --error: #ff7878;
  --error-bg: rgba(255, 120, 120, 0.12);
  --warning: #facc15;
  --radius: 8px;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --transition-theme: 0.35s ease;

  /* Syntax Highlighting Tokens (Dark Mode - Ultra High Contrast & Super Readable) */
  --cm-bg: #111320;
  --cm-gutter-bg: #0d0f1a;
  --cm-gutter-border: #1e2238;
  --cm-gutter-num: #64748b;
  --cm-cursor: #ff79c6;
  --cm-selection: rgba(255, 121, 198, 0.25);
  --cm-active-line: rgba(255, 255, 255, 0.04);

  --syn-keyword: #ff79c6;       /* Bright Glowing Neon Pink for def, return, if, for, import */
  --syn-builtin: #00e5ff;       /* Electric Bright Cyan for print, len, range, int, str, sum */
  --syn-atom: #ff9e64;          /* Bright Peach for True, False, None */
  --syn-def: #ffe600;           /* Glowing Gold/Yellow for function names def sum_list */
  --syn-string: #50fa7b;        /* Neon Lime Green for strings */
  --syn-string-2: #86efac;      /* Light Mint Green */
  --syn-number: #ffb86c;        /* Bright Amber/Orange for numbers */
  --syn-comment: #94a3b8;       /* Crisp Bright Slate Gray for comments (italics) */
  --syn-operator: #ff79c6;      /* Bright Coral/Pink for operators */
  --syn-property: #80d4ff;      /* Sky Blue for .read_csv, .groupby, .head */
  --syn-variable: #f8f8f2;      /* Pure Bright Crisp White for variables */
  --syn-variable-2: #ffb86c;    /* Bright Gold for parameters */
  --syn-bracket: #cbd5e1;       /* Light Steel for brackets () [] {} */
  --syn-bracket-match-bg: rgba(0, 229, 255, 0.25);
  --syn-bracket-match-border: #00e5ff;
}

[data-theme="light"] {
  --bg: #f8fafc;
  --bg-elevated: #ffffff;
  --bg-hover: rgba(217, 53, 53, 0.08);
  --border: #cbd5e1;
  --text: #0f172a;
  --text-muted: #64748b;
  --text-dim: #94a3b8;
  --accent: #d93535;
  --accent-dim: rgba(217, 53, 53, 0.09);
  --accent-soft: rgba(217, 53, 53, 0.04);
  --accent-glow: rgba(217, 53, 53, 0.22);
  --success: #15803d;
  --success-bg: rgba(21, 128, 61, 0.1);
  --error: #dc2626;
  --error-bg: rgba(220, 38, 38, 0.1);
  --warning: #b45309;

  /* Syntax Highlighting Tokens (Light Mode - Crisp & High Contrast) */
  --cm-bg: #ffffff;
  --cm-gutter-bg: #f8fafc;
  --cm-gutter-border: #e2e8f0;
  --cm-gutter-num: #94a3b8;
  --cm-cursor: #d93535;
  --cm-selection: rgba(217, 53, 53, 0.15);
  --cm-active-line: rgba(0, 0, 0, 0.03);

  --syn-keyword: #d92662;       /* Crimson Magenta */
  --syn-builtin: #0284c7;       /* Rich Deep Blue */
  --syn-atom: #c2410c;          /* Warm Terracotta */
  --syn-def: #7c3aed;           /* Royal Violet */
  --syn-string: #15803d;        /* Deep Emerald */
  --syn-string-2: #166534;      /* Dark Green */
  --syn-number: #b45309;        /* Deep Amber */
  --syn-comment: #64748b;       /* Muted Slate Gray (italics) */
  --syn-operator: #e11d48;      /* Rose Red */
  --syn-property: #0369a1;      /* Ocean Blue */
  --syn-variable: #0f172a;      /* Deep Slate */
  --syn-variable-2: #be123c;    /* Deep Rose */
  --syn-bracket: #475569;       /* Slate */
  --syn-bracket-match-bg: rgba(2, 132, 199, 0.18);
  --syn-bracket-match-border: #0284c7;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  background-image:
    radial-gradient(ellipse 60% 50% at 20% 10%, var(--accent-soft) 0%, transparent 60%),
    radial-gradient(ellipse 50% 40% at 80% 90%, var(--accent-soft) 0%, transparent 60%);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition-theme), color var(--transition-theme);
}

/* Header */
.header {
  display: flex;
  align-items: center;
  gap: 2.25rem;
  padding: 18px 48px;
  background: transparent;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  transition:
    background-color var(--transition-theme),
    border-color var(--transition-theme),
    color var(--transition-theme);
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.1rem;
}

.logo-icon {
  color: var(--accent);
  font-size: 1rem;
  text-shadow: 0 0 12px var(--accent-glow);
}

.logo-text {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 17px;
  font-weight: 500;
}

.nav-tabs {
  display: flex;
  gap: 0.25rem;
}

.header-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 12px;
}

.tab {
  background: none;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 6px 13px;
  border-radius: 999px;
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.tab:hover,
.tab.active {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.runtime-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-muted);
}

.theme-toggle {
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0;
  outline: none;
  transition:
    border-color var(--transition-theme),
    background var(--transition-theme),
    transform 0.15s;
}

.theme-toggle:hover {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.theme-toggle:active {
  transform: scale(0.94);
}

.t-icon {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition:
    transform 0.35s cubic-bezier(.4, 0, .2, 1),
    opacity 0.25s ease;
}

.t-icon svg {
  width: 16px;
  height: 16px;
}

.t-icon.icon-moon {
  transform: translateY(0) rotate(0deg);
  opacity: 1;
}

.t-icon.icon-sun {
  transform: translateY(110%) rotate(-30deg);
  opacity: 0;
}

[data-theme="light"] .t-icon.icon-moon {
  transform: translateY(-110%) rotate(30deg);
  opacity: 0;
}

[data-theme="light"] .t-icon.icon-sun {
  transform: translateY(0) rotate(0deg);
  opacity: 1;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
}

.status-dot.loading { background: var(--warning); animation: pulse 1.2s infinite; }
.status-dot.ready { background: var(--accent); box-shadow: 0 0 8px var(--accent-glow); }
.status-dot.error { background: var(--error); }

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

/* Main layout */
.main { flex: 1; overflow: hidden; min-height: 0; }

.tab-panel { display: none; height: 100%; }
.tab-panel.active {
  display: flex;
  animation: panelIn 0.28s cubic-bezier(.4, 0, .2, 1);
}

@keyframes panelIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Practice layout */
#tab-practice { gap: 0; }

.task-sidebar {
  width: 320px;
  flex-shrink: 0;
  border-right: 1px solid var(--border);
  background: var(--bg);
  overflow-y: auto;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.sidebar-header h2 {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  text-transform: lowercase;
}

.task-card {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  animation: cardIn 0.3s cubic-bezier(.4, 0, .2, 1);
}

@keyframes cardIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.task-meta { display: flex; gap: 0.5rem; flex-wrap: wrap; }

.badge {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  font-family: var(--font-mono);
  background: var(--accent-dim);
  color: var(--accent);
}

.badge.easy { background: var(--success-bg); color: var(--success); }
.badge.medium { background: rgba(255, 211, 122, 0.1); color: var(--warning); }
.badge.hard { background: var(--error-bg); color: var(--error); }
.badge.badge-muted { background: var(--accent-soft); color: var(--text-muted); }

#task-title { font-size: 1.05rem; line-height: 1.4; }

.task-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
  white-space: pre-wrap;
}

.task-hint {
  font-size: 0.8rem;
  color: var(--warning);
  background: rgba(255, 211, 122, 0.08);
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius);
  border-left: 3px solid var(--warning);
}

.task-sample {
  font-size: 0.8rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.6rem 0.75rem;
}

.task-sample-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
}

.task-sample-header code {
  display: inline-block;
  margin-top: 0.25rem;
}

.task-sample pre {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  overflow-x: auto;
  margin-top: 0.4rem;
  color: var(--text-muted);
}

.editor-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

.editor-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.toolbar-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.toolbar-actions {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.snippet-select {
  min-width: 136px;
  height: 33px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0 0.65rem;
  outline: none;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.snippet-select:hover,
.snippet-select:focus {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.snippet-select option {
  background: var(--bg-elevated);
  color: var(--text);
}

/* CodeMirror Custom Syntax Highlighting Theme */
.code-editor { flex: 1; overflow: hidden; }

.code-editor .CodeMirror {
  height: 100% !important;
  font-family: var(--font-mono);
  font-size: 14.5px;
  line-height: 1.65;
  background: var(--cm-bg);
  color: var(--syn-variable);
  letter-spacing: 0.15px;
}

.code-editor .CodeMirror-gutters {
  background: var(--cm-gutter-bg);
  border-right: 1px solid var(--cm-gutter-border);
}

.code-editor .CodeMirror-linenumber {
  color: var(--cm-gutter-num);
  font-size: 13px;
  padding: 0 8px 0 5px;
}

.code-editor .CodeMirror-cursor {
  border-left: 2px solid var(--cm-cursor);
}

.code-editor .CodeMirror-selected {
  background: var(--cm-selection) !important;
}

.code-editor .CodeMirror-activeline-background {
  background: var(--cm-active-line);
}

.code-editor .CodeMirror-matchingbracket {
  background: var(--syn-bracket-match-bg) !important;
  border-bottom: 2px solid var(--syn-bracket-match-border);
  color: var(--syn-builtin) !important;
  font-weight: 600;
}

/* Comprehensive Syntax Tokens (Overriding .cm-s-default defaults like #708 purple) */
.cm-s-default .cm-keyword,
.CodeMirror .cm-keyword,
.code-editor .cm-keyword {
  color: var(--syn-keyword) !important;
  font-weight: 600;
}

.cm-s-default .cm-builtin,
.CodeMirror .cm-builtin,
.code-editor .cm-builtin {
  color: var(--syn-builtin) !important;
  font-weight: 500;
}

.cm-s-default .cm-atom,
.CodeMirror .cm-atom,
.code-editor .cm-atom {
  color: var(--syn-atom) !important;
  font-weight: 600;
}

.cm-s-default .cm-def,
.CodeMirror .cm-def,
.code-editor .cm-def {
  color: var(--syn-def) !important;
  font-weight: 600;
}

.cm-s-default .cm-string,
.CodeMirror .cm-string,
.code-editor .cm-string {
  color: var(--syn-string) !important;
}

.cm-s-default .cm-string-2,
.CodeMirror .cm-string-2,
.code-editor .cm-string-2 {
  color: var(--syn-string-2) !important;
}

.cm-s-default .cm-number,
.CodeMirror .cm-number,
.code-editor .cm-number {
  color: var(--syn-number) !important;
  font-weight: 500;
}

.cm-s-default .cm-comment,
.CodeMirror .cm-comment,
.code-editor .cm-comment {
  color: var(--syn-comment) !important;
  font-style: italic;
}

.cm-s-default .cm-operator,
.CodeMirror .cm-operator,
.code-editor .cm-operator {
  color: var(--syn-operator) !important;
  font-weight: 500;
}

.cm-s-default .cm-property,
.CodeMirror .cm-property,
.code-editor .cm-property {
  color: var(--syn-property) !important;
}

.cm-s-default .cm-variable,
.CodeMirror .cm-variable,
.code-editor .cm-variable {
  color: var(--syn-variable) !important;
}

.cm-s-default .cm-variable-2,
.CodeMirror .cm-variable-2,
.code-editor .cm-variable-2 {
  color: var(--syn-variable-2) !important;
}

.cm-s-default .cm-punctuation,
.cm-s-default .cm-bracket,
.cm-s-default .cm-delimiter,
.CodeMirror .cm-punctuation,
.CodeMirror .cm-bracket,
.CodeMirror .cm-delimiter,
.code-editor .cm-punctuation,
.code-editor .cm-bracket,
.code-editor .cm-delimiter {
  color: var(--syn-bracket) !important;
}

/* VS Code Red Wavy Underline & Red Error Line Highlighting */
.cm-error-underline {
  text-decoration: underline wavy var(--error) !important;
  text-decoration-thickness: 2px !important;
  text-underline-offset: 3px !important;
  background-color: rgba(255, 120, 120, 0.08) !important;
  border-radius: 2px;
}

.cm-error-line {
  background-color: rgba(255, 120, 120, 0.12) !important;
  border-left: 3px solid var(--error) !important;
}

/* Auto-Correct Button */
.btn-autocorrect {
  background: linear-gradient(135deg, rgba(167, 139, 250, 0.2) 0%, rgba(247, 85, 85, 0.2) 100%);
  color: #a78bfa;
  border: 1px solid rgba(167, 139, 250, 0.5);
  font-weight: 600;
  box-shadow: 0 0 10px rgba(167, 139, 250, 0.15);
  transition: all 0.2s ease;
}

[data-theme="light"] .btn-autocorrect {
  background: linear-gradient(135deg, rgba(124, 58, 237, 0.1) 0%, rgba(217, 53, 53, 0.1) 100%);
  color: #7c3aed;
  border-color: rgba(124, 58, 237, 0.4);
}

.btn-autocorrect:hover:not(:disabled) {
  background: linear-gradient(135deg, rgba(167, 139, 250, 0.35) 0%, rgba(247, 85, 85, 0.35) 100%);
  border-color: #a78bfa;
  color: #ffffff;
  box-shadow: 0 0 14px rgba(167, 139, 250, 0.3);
  transform: translateY(-1px);
}

.btn-autocorrect:active:not(:disabled) {
  transform: translateY(0);
}

/* Skill Coach Panel Drawer */
.skill-coach {
  background: var(--bg);
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  transition: all 0.25s ease;
}

.skill-coach-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  background: var(--bg-elevated);
  cursor: pointer;
  user-select: none;
  border-bottom: 1px solid transparent;
  transition: background 0.15s ease;
}

.skill-coach-header:hover {
  background: var(--bg-hover);
}

.skill-coach.expanded .skill-coach-header {
  border-bottom-color: var(--border);
}

.coach-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.coach-icon {
  font-size: 1.1rem;
}

.coach-heading {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text);
}

.badge-coach {
  background: rgba(167, 139, 250, 0.15);
  color: #a78bfa;
  border: 1px solid rgba(167, 139, 250, 0.3);
  font-size: 0.72rem;
}

[data-theme="light"] .badge-coach {
  background: rgba(124, 58, 237, 0.1);
  color: #7c3aed;
  border-color: rgba(124, 58, 237, 0.3);
}

.badge-coach.has-issues {
  background: rgba(247, 85, 85, 0.18);
  color: var(--accent);
  border-color: var(--accent);
  animation: pulseBadge 1.5s infinite alternate;
}

@keyframes pulseBadge {
  from { box-shadow: 0 0 0px transparent; }
  to { box-shadow: 0 0 8px var(--accent-glow); }
}

.coach-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.coach-chevron {
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}

.skill-coach.expanded .coach-chevron {
  transform: rotate(180deg);
}

.skill-coach-body {
  max-height: 0;
  overflow-y: auto;
  transition: max-height 0.3s cubic-bezier(0.4, 0, 0.2, 1), padding 0.3s ease;
  background: var(--bg);
}

.skill-coach.expanded .skill-coach-body {
  max-height: 220px;
  padding: 0.75rem 1rem;
}

.skill-coach-list {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.coach-empty {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: italic;
}

/* Individual Coach Issue Card */
.coach-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.65rem 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  animation: cardIn 0.25s ease;
}

.coach-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}

.coach-card-title {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text);
}

.coach-card-desc {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.45;
}

.coach-card-rationale {
  font-size: 0.75rem;
  color: var(--syn-builtin);
  background: rgba(56, 189, 248, 0.08);
  border-left: 3px solid var(--syn-builtin);
  padding: 0.4rem 0.6rem;
  border-radius: 4px;
}

[data-theme="light"] .coach-card-rationale {
  color: #0369a1;
  background: rgba(2, 132, 199, 0.08);
  border-left-color: #0284c7;
}

.coach-diff {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background: var(--cm-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.4rem 0.6rem;
  margin-top: 0.2rem;
}

.diff-del {
  color: var(--error);
  text-decoration: line-through;
  opacity: 0.85;
}

.diff-add {
  color: var(--success);
  font-weight: 500;
}

/* Toast Banner notification for Auto-Correction */
.autocorrect-toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: var(--bg-elevated);
  border: 1px solid #a78bfa;
  border-left: 4px solid #a78bfa;
  color: var(--text);
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius);
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.35);
  z-index: 1000;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  animation: toastIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes toastIn {
  from { opacity: 0; transform: translateY(12px) scale(0.95); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

/* Diagnostic Box inside Console / Test output */
.diagnostic-card {
  background: rgba(167, 139, 250, 0.08);
  border: 1px solid rgba(167, 139, 250, 0.3);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  margin-top: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.diagnostic-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-weight: 600;
  color: #a78bfa;
}

.diagnostic-tip {
  color: var(--text-muted);
  font-size: 0.78rem;
  line-height: 1.5;
}

.output-panel {
  height: 220px;
  flex-shrink: 0;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  background: var(--bg);
}

.output-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.output-tab {
  background: none;
  border: none;
  color: var(--text-muted);
  padding: 0.4rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: color 0.15s;
}

.output-tab:hover { color: var(--text); }
.output-tab.active { color: var(--accent); border-bottom-color: var(--accent); }

.output-content {
  display: none;
  flex: 1;
  overflow: auto;
  padding: 0.75rem 1rem;
}

.output-content.active { display: block; }

.console-text {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--text-muted);
  line-height: 1.5;
}

.console-text .err { color: var(--error); }
.console-text .ok { color: var(--success); }

.test-results { display: flex; flex-direction: column; gap: 0.5rem; }

.test-case {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius);
  font-size: 0.8rem;
  font-family: var(--font-mono);
  animation: resultIn 0.24s ease;
}

@keyframes resultIn {
  from { opacity: 0; transform: translateX(-6px); }
  to { opacity: 1; transform: translateX(0); }
}

.test-case.pass { background: var(--success-bg); border: 1px solid rgba(154, 223, 143, 0.35); }
.test-case.fail { background: var(--error-bg); border: 1px solid rgba(255, 140, 140, 0.35); }

.test-icon { font-size: 1rem; flex-shrink: 0; }
.test-detail { color: var(--text-muted); margin-top: 0.25rem; font-size: 0.75rem; }

.test-summary {
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.5rem 0;
}

.test-summary.all-pass { color: var(--success); }
.test-summary.some-fail { color: var(--error); }

.plot-gallery {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: flex-start;
}

.plot-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  max-width: 480px;
  animation: cardIn 0.3s cubic-bezier(.4, 0, .2, 1);
}

.plot-card img {
  display: block;
  max-width: 100%;
  height: auto;
}

.plot-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0.75rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s, opacity 0.15s, transform 0.15s;
  white-space: nowrap;
}

.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-sm { padding: 0.3rem 0.65rem; font-size: 0.78rem; }

.btn-primary {
  background: var(--accent-dim);
  color: var(--accent);
  border-color: var(--accent);
}
.btn-primary:hover:not(:disabled) { background: var(--bg-hover); }

.btn-secondary {
  background: transparent;
  color: var(--text-muted);
  border-color: var(--border);
}
.btn-secondary:hover:not(:disabled) {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.btn-ghost {
  background: none;
  color: var(--text-muted);
  border-color: var(--border);
}
.btn-ghost:hover:not(:disabled) {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.btn:active:not(:disabled) {
  transform: scale(0.97);
}

/* Files tab */
#tab-files { padding: 1.5rem; overflow-y: auto; }

.files-layout {
  display: grid;
  grid-template-columns: 1fr 280px 1fr;
  gap: 1.5rem;
  max-width: 1400px;
  margin: 0 auto;
  height: 100%;
}

@media (max-width: 1000px) {
  .files-layout { grid-template-columns: 1fr; }
  .task-sidebar { width: 260px; }
}

.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 2.5rem 1.5rem;
  text-align: center;
  transition: border-color 0.2s, background 0.2s;
  cursor: pointer;
}

.drop-zone.drag-over {
  border-color: var(--accent);
  background: var(--accent-dim);
}

.drop-icon { font-size: 2.5rem; margin-bottom: 0.75rem; }
.drop-hint { font-size: 0.8rem; color: var(--text-muted); margin-top: 0.4rem; }

.link { color: var(--accent); cursor: pointer; text-decoration: underline; }

.files-info {
  margin-top: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.files-info code {
  font-family: var(--font-mono);
  background: var(--bg);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  font-size: 0.75rem;
}

.files-list-panel h3,
.preview-header h3 {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-weight: 500;
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.file-list { list-style: none; display: flex; flex-direction: column; gap: 0.35rem; }

.file-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  cursor: pointer;
  font-size: 0.82rem;
  transition: background 0.15s, border-color 0.15s;
}

.file-item:hover { background: var(--bg-hover); }
.file-item.selected { border-color: var(--accent); background: var(--accent-dim); }

.file-item-info { display: flex; flex-direction: column; gap: 0.1rem; min-width: 0; }
.file-item-name {
  font-family: var(--font-mono);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.file-item-size { font-size: 0.7rem; color: var(--text-muted); }

.file-item-actions { display: flex; gap: 0.25rem; flex-shrink: 0; }

.file-empty { font-size: 0.82rem; color: var(--text-muted); padding: 0.5rem; }

.file-preview-panel {
  display: flex;
  flex-direction: column;
  min-height: 300px;
}

.preview-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.file-preview {
  flex: 1;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: auto;
  padding: 1rem;
  min-height: 280px;
}

.file-preview pre {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--text-muted);
}

.file-preview img {
  max-width: 100%;
  border-radius: 4px;
}

.preview-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.78rem;
}

.preview-table th,
.preview-table td {
  border: 1px solid var(--border);
  padding: 0.35rem 0.6rem;
  text-align: left;
}

.preview-table th {
  background: var(--accent-soft);
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-weight: 500;
}

.preview-table tr:nth-child(even) td { background: var(--bg); }

.placeholder { color: var(--text-muted); font-size: 0.85rem; }

.hidden { display: none !important; }

/* VS Code Style Autocomplete Dropdown (.CodeMirror-hints) */
.CodeMirror-hints {
  position: absolute;
  z-index: 10000;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.55), 0 0 0 1px rgba(255, 255, 255, 0.05);
  padding: 4px;
  font-family: var(--font-mono);
  font-size: 13px;
  max-height: 220px;
  overflow-y: auto;
  min-width: 260px;
  backdrop-filter: blur(8px);
}

.CodeMirror-hint {
  padding: 0;
  border-radius: 4px;
  color: var(--text);
  cursor: pointer;
  margin-bottom: 2px;
}

.vscode-hint-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 5px 8px;
  width: 100%;
  border-radius: 4px;
}

.CodeMirror-hint-active .vscode-hint-item {
  background: var(--accent-dim) !important;
  color: #ffffff !important;
}

.vscode-hint-left {
  display: flex;
  align-items: center;
  gap: 8px;
}

.vscode-hint-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 700;
  font-family: var(--font-mono);
  flex-shrink: 0;
}

.vscode-hint-icon.icon-kw { background: rgba(255, 121, 198, 0.2); color: #ff79c6; border: 1px solid rgba(255, 121, 198, 0.4); }
.vscode-hint-icon.icon-fn { background: rgba(0, 229, 255, 0.2); color: #00e5ff; border: 1px solid rgba(0, 229, 255, 0.4); }
.vscode-hint-icon.icon-var { background: rgba(255, 230, 0, 0.2); color: #ffe600; border: 1px solid rgba(255, 230, 0, 0.4); }
.vscode-hint-icon.icon-mod { background: rgba(167, 139, 250, 0.2); color: #a78bfa; border: 1px solid rgba(167, 139, 250, 0.4); }

.vscode-hint-label {
  font-weight: 500;
  color: var(--text);
}

.CodeMirror-hint-active .vscode-hint-label {
  color: #ffffff;
  font-weight: 600;
}

.vscode-hint-type {
  font-size: 11px;
  color: var(--text-muted);
  font-style: italic;
  opacity: 0.8;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}