/* ===========================
   CSS VARIABLES & RESET
   =========================== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
    --primary:       #8b5cf6;
    --primary-dark:  #7c3aed;
    --secondary:     #10b981;
    --bg-primary:    #ffffff;
    --bg-secondary:  #f8fafc;
    --bg-card:       #ffffff;
    --text-primary:  #1f2937;
    --text-secondary:#6b7280;
    --border:        #e5e7eb;
    --shadow:        rgba(0,0,0,0.10);
    --shadow-lg:     rgba(0,0,0,0.15);
    --navbar-bg:     #ffffff;
    --gradient:      linear-gradient(135deg,#8b5cf6 0%,#10b981 100%);
    --code-bg:       #1e1e2e;
    --code-text:     #cdd6f4;
    --mono:          'IBM Plex Mono', monospace;
    --correct:       #10b981;
    --wrong:         #ef4444;
    --warning:       #f59e0b;
}

[data-theme="dark"] {
    --bg-primary:    #111827;
    --bg-secondary:  #1f2937;
    --bg-card:       #1f2937;
    --text-primary:  #f9fafb;
    --text-secondary:#d1d5db;
    --border:        #374151;
    --shadow:        rgba(0,0,0,0.30);
    --shadow-lg:     rgba(0,0,0,0.50);
    --navbar-bg:     #111827;
    --code-bg:       #0d1117;
    --code-text:     #c9d1d9;
}

html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    min-height: 100vh;
}

/* ===========================
   HERO
   =========================== */
.hero {
    background: var(--gradient);
    padding: 3.5rem 2rem;
    text-align: center;
    color: white;
    position: relative;
    overflow: hidden;
    border-bottom: 2px solid var(--border);
}
.hero::before {
    content: '';
    position: absolute; inset: 0;
    background-image: radial-gradient(rgba(255,255,255,0.14) 1px, transparent 1px);
    background-size: 26px 26px;
    opacity: 0.4;
    pointer-events: none;
}
.hero-content {
    position: relative; z-index: 1;
    max-width: 820px; margin: 0 auto;
}
.hero-h1 {
    font-size: clamp(2rem, 5vw, 3.2rem);
    font-weight: 800; margin-bottom: 0.85rem;
    display: flex; align-items: center; justify-content: center; gap: 0.9rem;
}
.hero-para { font-size: 1.15rem; opacity: 0.92; margin-bottom: 1.8rem; }
.hero-stats {
    display: flex; justify-content: center; gap: 1.4rem; flex-wrap: wrap;
}
.hero-stats span {
    background: rgba(255,255,255,0.18);
    padding: 7px 18px; border-radius: 50px;
    display: flex; align-items: center; gap: 7px;
    backdrop-filter: blur(10px); font-size: 0.9rem;
}
[data-theme="dark"] .hero { background: linear-gradient(to right,#111827,#1f2937); }
[data-theme="dark"] .hero-h1 {
    background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
[data-theme="dark"] .hero-para {
    background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
[data-theme="dark"] .hero-stats span {
    background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent;
    border: 1px solid #7c3aed;
}

/* ===========================
   CONTAINER
   =========================== */
.container { max-width: 1600px; margin: 0 auto; padding: 2rem; }

/* ===========================
   CONTROLS BAR
   =========================== */
.controls-bar {
    display: flex; align-items: center;
    gap: 24px; flex-wrap: wrap;
    background: var(--bg-card);
    border-radius: 16px; border: 2px solid var(--border);
    box-shadow: 0 4px 20px var(--shadow);
    padding: 16px 24px; margin-bottom: 24px;
}
.controls-label {
    display: flex; align-items: center; gap: 7px;
    font-weight: 600; font-size: 0.9rem; color: var(--text-secondary);
    white-space: nowrap;
}
.difficulty-group { display: flex; align-items: center; gap: 12px; }
.diff-tabs { display: flex; gap: 6px; }
.diff-tab {
    display: flex; align-items: center; gap: 6px;
    padding: 8px 18px; border-radius: 10px;
    background: var(--bg-secondary); border: 2px solid var(--border);
    color: var(--text-secondary); font-size: 0.88rem; font-weight: 600;
    cursor: pointer; font-family: 'Inter', sans-serif;
    transition: all 0.25s ease;
}
.diff-tab:hover { border-color: var(--primary); color: var(--primary); transform: translateY(-1px); }
.diff-tab.active { background: var(--gradient); color: white; border-color: transparent; box-shadow: 0 4px 14px rgba(139,92,246,0.35); }

/* Progress tracker */
.progress-tracker { flex: 1; min-width: 180px; display: flex; flex-direction: column; gap: 6px; }
.progress-info { display: flex; justify-content: space-between; align-items: center; font-size: 0.85rem; color: var(--text-secondary); }
.score-display { display: flex; align-items: center; gap: 5px; color: var(--secondary); font-weight: 600; }
.progress-bar-wrap { height: 6px; background: var(--bg-secondary); border-radius: 3px; border: 1px solid var(--border); overflow: hidden; }
.progress-bar-fill { height: 100%; width: 0%; background: var(--gradient); border-radius: 3px; transition: width 0.5s ease; }

/* Timed toggle */
.timed-toggle-group { display: flex; align-items: center; gap: 12px; }
.toggle-switch { position: relative; display: inline-block; width: 46px; height: 24px; cursor: pointer; }
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.toggle-slider {
    position: absolute; inset: 0; background: var(--border);
    border-radius: 12px; transition: 0.3s ease;
}
.toggle-slider::before {
    content: ''; position: absolute;
    width: 18px; height: 18px; left: 3px; bottom: 3px;
    background: white; border-radius: 50%;
    transition: 0.3s ease; box-shadow: 0 1px 4px rgba(0,0,0,0.2);
}
.toggle-switch input:checked + .toggle-slider { background: var(--primary); }
.toggle-switch input:checked + .toggle-slider::before { transform: translateX(22px); }

/* ===========================
   WORKSPACE LAYOUT
   =========================== */
.workspace {
    display: grid;
    grid-template-columns: 420px 1fr;
    gap: 20px;
    align-items: start;
}

/* ===========================
   PANEL CARD (base)
   =========================== */
.panel-card {
    background: var(--bg-card);
    border-radius: 16px;
    border: 2px solid var(--border);
    box-shadow: 0 4px 20px var(--shadow);
    overflow: hidden;
    margin-bottom: 20px;
    transition: border-color 0.25s ease;
}
.panel-card:last-child { margin-bottom: 0; }

.panel-header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 14px 20px;
    background: rgba(139,92,246,0.08);
    border-bottom: 2px solid var(--border);
    font-weight: 700; font-size: 0.95rem; color: var(--text-primary);
}
.panel-header > span {
    display: flex; align-items: center; gap: 8px;
}
.panel-header > span i {
    color: var(--primary);
}
.panel-header-right { display: flex; align-items: center; gap: 10px; }

/* Difficulty badge */
.diff-badge {
    padding: 3px 11px; border-radius: 20px; font-size: 0.75rem; font-weight: 700;
    text-transform: uppercase; letter-spacing: 0.05em;
}
.diff-badge.easy       { background: rgba(16,185,129,0.14); color: #10b981; border: 1px solid rgba(16,185,129,0.3); }
.diff-badge.medium     { background: rgba(245,158,11,0.14); color: #f59e0b; border: 1px solid rgba(245,158,11,0.3); }
.diff-badge.hard       { background: rgba(239,68,68,0.14);  color: #ef4444; border: 1px solid rgba(239,68,68,0.3); }

/* ===========================
   QUESTION CARD
   =========================== */
.question-body { padding: 20px 20px 12px; }
.question-title {
    font-size: 1.25rem; font-weight: 800; color: var(--text-primary);
    margin-bottom: 8px; line-height: 1.3;
}
.question-desc { font-size: 0.93rem; color: var(--text-secondary); line-height: 1.65; margin-bottom: 18px; }

.expected-cols { display: flex; align-items: flex-start; gap: 10px; flex-wrap: wrap; }
.expected-label { font-size: 0.8rem; font-weight: 700; color: var(--text-secondary); white-space: nowrap; padding-top: 3px; }
.expected-tags { display: flex; gap: 7px; flex-wrap: wrap; }
.expected-tag {
    padding: 3px 10px; border-radius: 6px; font-size: 0.78rem; font-weight: 600;
    background: var(--bg-secondary); border: 1.5px solid var(--border);
    color: var(--text-secondary); font-family: var(--mono);
}

/* Question action row */
.question-actions {
    display: flex; align-items: center; justify-content: space-between;
    padding: 12px 20px 16px; gap: 10px; flex-wrap: wrap;
    border-top: 1px solid var(--border); background: var(--bg-secondary);
}
.nav-btns, .action-btns { display: flex; gap: 8px; }

.nav-btn {
    display: flex; align-items: center; gap: 6px;
    padding: 8px 16px; border-radius: 9px; font-size: 0.87rem; font-weight: 600;
    background: var(--bg-card); border: 2px solid var(--border); color: var(--text-primary);
    cursor: pointer; font-family: 'Inter', sans-serif; transition: all 0.22s ease;
}
.nav-btn:hover:not(:disabled) { border-color: var(--primary); color: var(--primary); transform: translateY(-1px); }
.nav-btn:disabled { opacity: 0.35; cursor: not-allowed; }

.action-btn {
    display: flex; align-items: center; gap: 6px;
    padding: 8px 16px; border-radius: 9px; font-size: 0.87rem; font-weight: 600;
    cursor: pointer; font-family: 'Inter', sans-serif; border: none;
    transition: all 0.22s ease;
}
.btn-hint     { background: rgba(245,158,11,0.12); color: #d97706; border: 1.5px solid rgba(245,158,11,0.3); }
.btn-solution { background: rgba(139,92,246,0.12); color: var(--primary); border: 1.5px solid rgba(139,92,246,0.3); }
.btn-hint:hover     { background: rgba(245,158,11,0.22); transform: translateY(-1px); }
.btn-solution:hover { background: rgba(139,92,246,0.2); transform: translateY(-1px); }

.btn-reset {
    background: var(--bg-secondary); color: var(--text-secondary);
    border: 1.5px solid var(--border);
}
.btn-reset:hover { border-color: var(--wrong); color: var(--wrong); transform: translateY(-1px); }

.btn-run {
    background: var(--gradient); color: white;
    padding: 8px 22px; font-size: 0.92rem;
    box-shadow: 0 4px 14px rgba(139,92,246,0.35);
}
.btn-run:hover { transform: translateY(-2px); box-shadow: 0 7px 22px rgba(139,92,246,0.45); }
.btn-run.running { opacity: 0.8; pointer-events: none; }

.icon-btn {
    display: flex; align-items: center; justify-content: center;
    width: 30px; height: 30px; border-radius: 7px;
    background: var(--bg-secondary); border: 1.5px solid var(--border);
    color: var(--text-secondary); cursor: pointer; font-size: 0.82rem;
    transition: all 0.2s ease;
}
.icon-btn:hover { border-color: var(--primary); color: var(--primary); }

/* ===========================
   HINT / SOLUTION REVEAL
   =========================== */
.reveal-card { margin-bottom: 20px; }
.reveal-body {
    padding: 16px 20px; font-size: 0.9rem;
    color: var(--text-secondary); line-height: 1.65;
}
.reveal-body code {
    background: rgba(139,92,246,0.1); color: var(--primary);
    padding: 2px 7px; border-radius: 5px;
    font-family: var(--mono); font-size: 0.85em;
    border: 1px solid rgba(139,92,246,0.2);
}
.reveal-body pre {
    background: var(--code-bg); border-radius: 10px;
    padding: 14px 16px; margin-top: 10px; overflow-x: auto;
    border: 1px solid rgba(255,255,255,0.06);
}
.reveal-body pre code {
    background: transparent; border: none; color: var(--code-text);
    font-size: 0.88rem; padding: 0;
}

/* ===========================
   DATABASE INFO CARD
   =========================== */
.db-view-tabs { display: flex; gap: 6px; }
.db-tab {
    display: flex; align-items: center; gap: 5px;
    padding: 5px 13px; border-radius: 8px; font-size: 0.82rem; font-weight: 600;
    background: var(--bg-secondary); border: 1.5px solid var(--border);
    color: var(--text-secondary); cursor: pointer; font-family: 'Inter', sans-serif;
    transition: all 0.2s ease;
}
.db-tab:hover { border-color: var(--primary); color: var(--primary); }
.db-tab.active { background: var(--gradient); color: white; border-color: transparent; }

.db-view { padding: 16px 20px; }
.schema-header { margin-bottom: 14px; }
.schema-header h3 { font-size: 0.95rem; font-weight: 800; color: var(--text-primary); margin-bottom: 2px; }
.schema-header p  { font-size: 0.8rem; color: var(--text-secondary); }

.table-navigator {
    display: flex; align-items: center; gap: 10px;
    padding: 8px 0 12px;
    border-bottom: 1px solid var(--border); margin-bottom: 14px;
}
.table-name-label { flex: 1; font-family: var(--mono); font-size: 0.9rem; font-weight: 700; color: var(--text-primary); text-align: center; }
.table-count { color: var(--text-secondary); font-weight: 400; }

/* Schema table display */
.schema-table-card {
    border: 2px solid var(--border); border-radius: 10px;
    overflow: hidden; margin-bottom: 14px;
}
.schema-table-title {
    display: flex; align-items: center; gap: 8px;
    padding: 9px 14px;
    background: rgba(139,92,246,0.08);
    border-bottom: 1px solid var(--border);
    font-weight: 700; font-size: 0.88rem; color: var(--text-primary);
    font-family: var(--mono);
}
.schema-table-title i { color: var(--primary); }
.schema-col-row {
    display: flex; align-items: center; justify-content: space-between;
    padding: 7px 14px;
    border-bottom: 1px solid var(--border);
    font-size: 0.83rem;
}
.schema-col-row:last-child { border-bottom: none; }
.schema-col-name { font-family: var(--mono); color: var(--text-primary); font-weight: 500; display: flex; align-items: center; gap: 6px; }
.schema-col-type { font-family: var(--mono); color: var(--text-secondary); font-size: 0.78rem; }
.pk-badge { font-size: 0.65rem; color: var(--warning); font-weight: 700; }
.fk-badge { font-size: 0.65rem; color: var(--secondary); font-weight: 700; }

.relationships-wrap { margin-top: 8px; }
.rel-title { font-size: 0.8rem; font-weight: 700; color: var(--text-secondary); margin-bottom: 7px; }
.rel-item {
    font-size: 0.78rem; color: var(--text-secondary);
    font-family: var(--mono); padding: 3px 0;
    display: flex; align-items: center; gap: 5px;
}
.rel-item i { color: var(--primary); font-size: 0.65rem; }

/* Data table */
.data-table-scroll { overflow-x: auto; border-radius: 8px; border: 1px solid var(--border); }
.data-table { width: 100%; border-collapse: collapse; font-size: 0.78rem; }
.data-table thead th {
    background: rgba(139,92,246,0.08); padding: 8px 10px;
    text-align: left; font-weight: 700; color: var(--text-primary);
    border-bottom: 2px solid var(--border); font-family: var(--mono);
    white-space: nowrap;
}
.data-table tbody td {
    padding: 6px 10px; border-bottom: 1px solid var(--border);
    color: var(--text-secondary); font-family: var(--mono); white-space: nowrap;
}
.data-table tbody tr:last-child td { border-bottom: none; }
.data-table tbody tr:hover { background: var(--bg-secondary); }

/* ===========================
   SQL EDITOR
   =========================== */
.editor-card { }
.editor-header-btns { display: flex; gap: 8px; }

.editor-wrap {
    position: relative; display: flex;
    height: 380px;
    background: var(--code-bg);
    overflow: hidden;
}

.line-numbers {
    min-width: 48px; padding: 16px 10px 16px 14px;
    background: rgba(255,255,255,0.03);
    border-right: 1px solid rgba(255,255,255,0.07);
    font-family: var(--mono); font-size: 0.82rem;
    color: rgba(255,255,255,0.2); line-height: 1.65;
    user-select: none; text-align: right;
    overflow: hidden;
    flex-shrink: 0;
}

.sql-editor {
    flex: 1; padding: 16px 16px 16px 14px;
    background: transparent; border: none; outline: none;
    font-family: var(--mono); font-size: 0.88rem;
    color: transparent; /* text hidden — overlay renders colored version */
    caret-color: #a78bfa;
    line-height: 1.65; resize: none;
    tab-size: 4; white-space: pre;
    overflow-x: auto; overflow-y: auto;
    position: relative; z-index: 2;
    width: 100%;
}

/* Syntax highlight overlay */
.editor-overlay {
    position: absolute; top: 0; left: 48px; right: 0; bottom: 0;
    padding: 16px 16px 16px 14px;
    font-family: var(--mono); font-size: 0.88rem; line-height: 1.65;
    color: var(--code-text); pointer-events: none; z-index: 1;
    white-space: pre; overflow: hidden;
    word-break: keep-all;
}

/* Syntax token colours */
.tok-kw      { color: #c084fc; font-weight: 600; }
.tok-fn      { color: #6ee7b7; }
.tok-str     { color: #fca5a5; }
.tok-num     { color: #fcd34d; }
.tok-cmt     { color: #64748b; font-style: italic; }
.tok-op      { color: #94a3b8; }
.tok-tbl     { color: #7dd3fc; }
.tok-punct   { color: #94a3b8; }

.editor-footer {
    display: flex; align-items: center; justify-content: space-between;
    padding: 8px 16px; background: rgba(0,0,0,0.15);
    border-top: 1px solid rgba(255,255,255,0.06);
    gap: 12px;
}
.kb-hint {
    font-size: 0.76rem; color: rgba(255,255,255,0.35);
    display: flex; align-items: center; gap: 4px;
}
kbd {
    padding: 1px 5px; border-radius: 4px;
    background: rgba(255,255,255,0.1);
    border: 1px solid rgba(255,255,255,0.15);
    font-family: var(--mono); font-size: 0.72rem;
    color: rgba(255,255,255,0.5);
}
.char-count { font-size: 0.76rem; color: rgba(255,255,255,0.3); font-family: var(--mono); margin-left: auto; }

/* ===========================
   RESULTS CARD
   =========================== */
.results-card { }
.result-meta { display: flex; gap: 12px; align-items: center; }
.result-rows, .result-time {
    display: flex; align-items: center; gap: 5px;
    padding: 3px 10px; border-radius: 20px; font-size: 0.8rem; font-weight: 600;
    background: var(--bg-secondary); border: 1px solid var(--border);
    color: var(--text-secondary);
}
.result-rows i { color: var(--secondary); }
.result-time i { color: var(--primary); }

.results-body { min-height: 200px; }

.results-empty, .results-error {
    display: flex; flex-direction: column; align-items: center; justify-content: center;
    gap: 12px; padding: 40px 20px;
    color: var(--text-secondary); font-size: 0.92rem;
    min-height: 200px;
}
.results-empty i { font-size: 2.5rem; opacity: 0.3; }
.results-error i { font-size: 2rem; color: var(--wrong); opacity: 0.7; }
.results-error p  { color: var(--wrong); font-family: var(--mono); font-size: 0.85rem; text-align: center; max-width: 400px; }

.results-table-wrap { overflow-x: auto; }
.results-table {
    width: 100%; border-collapse: collapse;
    font-size: 0.83rem;
}
.results-table thead th {
    background: rgba(139,92,246,0.1); padding: 10px 14px;
    text-align: left; font-weight: 700; color: var(--text-primary);
    border-bottom: 2px solid var(--border);
    font-family: var(--mono); white-space: nowrap; font-size: 0.8rem;
    position: sticky; top: 0; z-index: 1;
}
.results-table tbody td {
    padding: 8px 14px; border-bottom: 1px solid var(--border);
    color: var(--text-secondary); font-family: var(--mono);
    white-space: nowrap;
}
.results-table tbody tr:last-child td { border-bottom: none; }
.results-table tbody tr:hover { background: var(--bg-secondary); }
.results-table .null-val { color: var(--text-secondary); opacity: 0.4; font-style: italic; }

/* Verdict banner */
.verdict-banner { border-top: 2px solid var(--border); }
.verdict-inner {
    display: flex; align-items: center; gap: 14px;
    padding: 14px 20px; font-weight: 700; font-size: 0.95rem;
}
.verdict-inner.correct { background: rgba(16,185,129,0.1); color: var(--correct); }
.verdict-inner.wrong   { background: rgba(239,68,68,0.08); color: var(--wrong); }
.verdict-inner.partial { background: rgba(245,158,11,0.1); color: var(--warning); }
.verdict-inner i { font-size: 1.3rem; }
.verdict-detail { font-weight: 400; font-size: 0.85rem; opacity: 0.85; margin-left: 4px; }

/* ===========================
   TIMER RING
   =========================== */
.timer-wrap { position: relative; width: 40px; height: 40px; flex-shrink: 0; }
.timer-ring { width: 40px; height: 40px; transform: rotate(-90deg); }
.timer-track { fill: none; stroke: rgba(255,255,255,0.15); stroke-width: 3; }
.timer-arc {
    fill: none; stroke: var(--secondary); stroke-width: 3; stroke-linecap: round;
    stroke-dasharray: 113.1; stroke-dashoffset: 0;
    transition: stroke-dashoffset 1s linear, stroke 0.3s ease;
}
.timer-arc.urgent { stroke: var(--wrong); animation: timerPulse 0.5s ease infinite; }
@keyframes timerPulse { 0%,100%{opacity:1} 50%{opacity:0.55} }
.timer-num {
    position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%);
    font-size: 0.72rem; font-weight: 800; color: var(--text-primary);
    font-family: var(--mono); pointer-events: none;
}

/* ===========================
   NOTIFICATION
   =========================== */
.notification {
    position: fixed; top: 80px; right: 20px;
    padding: 14px 22px; background: var(--gradient); color: white;
    border-radius: 10px; box-shadow: 0 4px 20px rgba(139,92,246,0.4);
    transform: translateX(420px); transition: transform 0.4s ease;
    z-index: 1000; font-weight: 500;
    display: flex; align-items: center; gap: 9px; font-size: 0.92rem;
}
.notification.show    { transform: translateX(0); }
.notification.success { background: linear-gradient(135deg,#10b981,#059669); }
.notification.error   { background: linear-gradient(135deg,#ef4444,#dc2626); }
.notification.warning { background: linear-gradient(135deg,#f59e0b,#d97706); }

/* ===========================
   ANIMATIONS
   =========================== */
@keyframes fadeIn { from{opacity:0} to{opacity:1} }
@keyframes slideUp { from{opacity:0;transform:translateY(16px)} to{opacity:1;transform:translateY(0)} }
.panel-card { animation: slideUp 0.35s ease; }

/* ===========================
   RESPONSIVE
   =========================== */
@media (max-width: 1200px) {
    .workspace { grid-template-columns: 380px 1fr; gap: 16px; }
}
@media (max-width: 1024px) {
    .workspace { grid-template-columns: 1fr; }
    .editor-wrap { height: 300px; }
}
@media (max-width: 768px) {
    .container { padding: 1.5rem; }
    .hero-h1 { font-size: 1.9rem; flex-direction: column; gap: 0.4rem; }
    .hero-para { font-size: 1rem; }
    .controls-bar { flex-direction: column; align-items: flex-start; gap: 16px; }
    .diff-tabs { flex-wrap: wrap; }
    .question-actions { flex-direction: column; gap: 10px; }
    .nav-btns, .action-btns { width: 100%; }
    .nav-btn, .action-btn { flex: 1; justify-content: center; }
}
@media (max-width: 576px) {
    .container { padding: 1rem; }
    .hero { padding: 2.5rem 1rem; }
    .hero-h1 { font-size: 1.7rem; }
    .notification { left: 10px; right: 10px; width: calc(100% - 20px); top: 70px; transform: translateY(-100px); }
    .notification.show { transform: translateY(0); }
    .editor-wrap { height: 260px; }
}