/* ================================================================
   postgresql-interview-prep.css — Sqlism Theme
   ================================================================ */
*,*::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,.10);--shadow-lg:rgba(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;
    /* difficulty */
    --c-beginner:#10b981;--c-intermediate:#f59e0b;--c-advanced:#8b5cf6;--c-tricky:#ef4444;
    /* PostgreSQL topic palette */
    --c-core:#336791;    /* classic Postgres blue */
    --c-indexes:#8b5cf6;
    --c-mvcc:#10b981;
    --c-perf:#ef4444;
    --c-json:#f59e0b;
    --c-repl:#3b82f6;
    --c-admin:#ec4899;
}
[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,.30);--shadow-lg:rgba(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 .3s ease,color .3s ease;min-height:100vh}
a{color:var(--primary);text-decoration:none}

/* ── HERO ── */
.hero{background:var(--gradient);padding:3.8rem 2rem 4.2rem;text-align:center;color:#fff;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,.14) 1px,transparent 1px);background-size:26px 26px;opacity:.4;pointer-events:none}
.hero::after{content:'';position:absolute;inset:0;background:radial-gradient(ellipse 55% 70% at 8% 60%,rgba(255,255,255,.07) 0%,transparent 60%),radial-gradient(ellipse 40% 50% at 92% 20%,rgba(255,255,255,.06) 0%,transparent 60%);pointer-events:none}
.hero-content{position:relative;z-index:1;max-width:820px;margin:0 auto}
.hero-eyebrow{display:inline-flex;align-items:center;gap:8px;background:rgba(255,255,255,.18);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.3);padding:6px 18px;border-radius:50px;font-size:.82rem;font-weight:700;letter-spacing:.05em;text-transform:uppercase;margin-bottom:18px}
.hero-h1{font-size:clamp(2rem,5vw,3.4rem);font-weight:800;margin-bottom:14px;display:block;letter-spacing:-.02em}
.hero-para{font-size:clamp(.95rem,2vw,1.15rem);opacity:.92;margin-bottom:24px;max-width:660px;margin-left:auto;margin-right:auto}
.hero-stats{display:flex;justify-content:center;gap:1.2rem;flex-wrap:wrap}
.hero-stats span{background:rgba(255,255,255,.18);padding:7px 18px;border-radius:50px;display:flex;align-items:center;gap:7px;backdrop-filter:blur(10px);font-size:.88rem}
[data-theme="dark"] .hero{background:linear-gradient(to right,#111827,#1f2937)}
[data-theme="dark"] .hero-h1,[data-theme="dark"] .hero-para,[data-theme="dark"] .hero-eyebrow{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:1100px;margin:0 auto;padding:2.5rem 2rem}

/* ── TOOLBAR ── */
.toolbar{background:var(--bg-card);border-radius:16px;border:2px solid var(--border);box-shadow:0 4px 20px var(--shadow);padding:20px 24px;margin-bottom:24px;display:flex;flex-direction:column;gap:16px}
.search-wrap{position:relative;display:flex;align-items:center}
.search-icon{position:absolute;left:14px;color:var(--text-secondary);font-size:.9rem;pointer-events:none}
.search-input{width:100%;padding:11px 40px;background:var(--bg-secondary);border:2px solid var(--border);border-radius:12px;color:var(--text-primary);font-size:.95rem;font-family:'Inter',sans-serif;transition:all .25s ease;outline:none}
.search-input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(139,92,246,.1)}
.search-clear{position:absolute;right:12px;background:none;border:none;color:var(--text-secondary);cursor:pointer;padding:4px;border-radius:50%;display:flex;align-items:center;justify-content:center;transition:color .2s ease}
.search-clear:hover{color:var(--primary)}

/* Difficulty tabs */
.diff-tabs{display:flex;gap:8px;flex-wrap:wrap}
.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:.87rem;font-weight:600;cursor:pointer;font-family:'Inter',sans-serif;transition:all .22s ease}
.diff-tab:hover{border-color:var(--primary);color:var(--primary);transform:translateY(-1px)}
.diff-tab.active{background:var(--gradient);color:#fff;border-color:transparent;box-shadow:0 4px 14px rgba(139,92,246,.35)}
.diff-tab.diff-beginner:not(.active):hover{border-color:var(--c-beginner);color:var(--c-beginner)}
.diff-tab.diff-intermediate:not(.active):hover{border-color:var(--c-intermediate);color:var(--c-intermediate)}
.diff-tab.diff-advanced:not(.active):hover{border-color:var(--c-advanced);color:var(--c-advanced)}
.diff-tab.diff-tricky:not(.active):hover{border-color:var(--c-tricky);color:var(--c-tricky)}

/* Topic pills */
.topic-pills{display:flex;gap:7px;flex-wrap:wrap}
.topic-pill{padding:5px 14px;border-radius:50px;font-size:.8rem;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 .2s ease}
.topic-pill:hover{border-color:var(--primary);color:var(--primary)}
.topic-pill.active{background:var(--gradient);color:#fff;border-color:transparent}

/* Stats row */
.stats-row{display:flex;align-items:center;gap:16px;flex-wrap:wrap;border-top:1px solid var(--border);padding-top:14px}
.stats-item{display:flex;align-items:center;gap:6px;font-size:.83rem;color:var(--text-secondary)}
.stats-item i{color:var(--primary)}
.btn-bookmarks-only{margin-left:auto;display:flex;align-items:center;gap:6px;padding:7px 16px;border-radius:9px;font-size:.83rem;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 .22s ease}
.btn-bookmarks-only:hover{border-color:var(--primary);color:var(--primary)}
.btn-bookmarks-only.active{background:rgba(139,92,246,.12);border-color:var(--primary);color:var(--primary)}

/* ── STUDY MODE BAR ── */
.study-mode-bar{background:var(--bg-card);border-radius:12px;border:2px solid var(--border);padding:14px 22px;margin-bottom:22px}
.study-mode-inner{display:flex;align-items:center;justify-content:space-between;gap:16px}
.study-mode-left{display:flex;align-items:center;gap:12px}
.study-mode-left>i{font-size:1.2rem;color:var(--primary)}
.study-mode-left>span:first-of-type{font-weight:700;color:var(--text-primary);font-size:.95rem}
.study-mode-desc{font-size:.82rem;color:var(--text-secondary)}
.toggle-switch{position:relative;display:inline-block;width:46px;height:24px;cursor:pointer;flex-shrink:0}
.toggle-switch input{opacity:0;width:0;height:0}
.toggle-slider{position:absolute;inset:0;background:var(--border);border-radius:12px;transition:.3s ease}
.toggle-slider::before{content:'';position:absolute;width:18px;height:18px;left:3px;bottom:3px;background:white;border-radius:50%;transition:.3s ease;box-shadow:0 1px 4px rgba(0,0,0,.2)}
.toggle-switch input:checked+.toggle-slider{background:var(--primary)}
.toggle-switch input:checked+.toggle-slider::before{transform:translateX(22px)}

/* ── Q&A GRID ── */
.qa-grid{display:flex;flex-direction:column;gap:14px;margin-bottom:28px}

/* ── QA CARD ── */
.qa-card{background:var(--bg-card);border-radius:16px;border:2px solid var(--border);box-shadow:0 4px 20px var(--shadow);overflow:hidden;transition:border-color .25s ease,box-shadow .25s ease;animation:fadeInUp .35s ease both}
.qa-card:hover{border-color:var(--primary);box-shadow:0 6px 28px rgba(139,92,246,.12)}
.qa-card.bookmarked{border-color:var(--secondary)}
@keyframes fadeInUp{from{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}

.qa-header{display:flex;align-items:center;gap:12px;padding:16px 20px;cursor:pointer;user-select:none;transition:background .2s ease}
.qa-header:hover{background:rgba(139,92,246,.04)}
.qa-number{font-family:var(--mono);font-size:.8rem;font-weight:700;color:var(--text-secondary);min-width:28px;flex-shrink:0}
.qa-badges{display:flex;gap:6px;align-items:center;flex-shrink:0;flex-wrap:wrap}

/* Difficulty badges */
.badge-diff{display:inline-flex;align-items:center;gap:4px;padding:3px 10px;border-radius:20px;font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;white-space:nowrap}
.badge-diff.beginner{background:rgba(16,185,129,.12);color:var(--c-beginner)}
.badge-diff.intermediate{background:rgba(245,158,11,.12);color:var(--c-intermediate)}
.badge-diff.advanced{background:rgba(139,92,246,.12);color:var(--c-advanced)}
.badge-diff.tricky{background:rgba(239,68,68,.12);color:var(--c-tricky)}

/* Topic badges */
.badge-topic{display:inline-flex;align-items:center;gap:4px;padding:3px 10px;border-radius:20px;font-size:.72rem;font-weight:600;white-space:nowrap}
.badge-topic.core-sql{background:rgba(51,103,145,.12);color:var(--c-core)}
.badge-topic.indexes{background:rgba(139,92,246,.12);color:var(--c-indexes)}
.badge-topic.mvcc{background:rgba(16,185,129,.12);color:var(--c-mvcc)}
.badge-topic.performance{background:rgba(239,68,68,.12);color:var(--c-perf)}
.badge-topic.json{background:rgba(245,158,11,.12);color:var(--c-json)}
.badge-topic.replication{background:rgba(59,130,246,.12);color:var(--c-repl)}
.badge-topic.admin{background:rgba(236,72,153,.12);color:var(--c-admin)}

.tricky-flame{font-size:.85rem;animation:flicker 1.4s ease-in-out infinite}
@keyframes flicker{0%,100%{opacity:1}50%{opacity:.65}}
.qa-question{flex:1;font-size:.97rem;font-weight:600;color:var(--text-primary);line-height:1.45}
.qa-actions{display:flex;align-items:center;gap:8px;flex-shrink:0;margin-left:auto}
.btn-bookmark{width:30px;height:30px;border-radius:8px;background:none;border:1.5px solid var(--border);color:var(--text-secondary);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:.8rem;transition:all .2s ease}
.btn-bookmark:hover{border-color:var(--secondary);color:var(--secondary)}
.btn-bookmark.active{background:rgba(16,185,129,.12);border-color:var(--secondary);color:var(--secondary)}
.qa-chevron{width:28px;height:28px;border-radius:7px;background:var(--bg-secondary);border:1.5px solid var(--border);color:var(--text-secondary);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:.75rem;transition:all .25s ease}
.qa-card.open .qa-chevron{background:var(--gradient);color:#fff;border-color:transparent}

/* Answer body */
.qa-body{display:none;border-top:2px solid var(--border);animation:bodySlide .28s ease}
.qa-card.open .qa-body{display:block}
@keyframes bodySlide{from{opacity:0;transform:translateY(-8px)}to{opacity:1;transform:translateY(0)}}

/* Study mode — only reveal when BOTH open AND study-hidden */
.qa-study-reveal{display:none;padding:20px;border-top:2px dashed var(--border);background:var(--bg-secondary);text-align:center}
.qa-card.open.study-hidden .qa-body{display:none!important}
.qa-card.open.study-hidden .qa-study-reveal{display:block}

.btn-reveal{display:inline-flex;align-items:center;gap:8px;padding:10px 22px;border-radius:10px;background:var(--gradient);color:#fff;border:none;font-size:.9rem;font-weight:600;cursor:pointer;font-family:'Inter',sans-serif;transition:all .25s ease;box-shadow:0 4px 14px rgba(139,92,246,.3)}
.btn-reveal:hover{transform:translateY(-2px);box-shadow:0 7px 22px rgba(139,92,246,.4)}

/* Answer content */
.answer-wrap{padding:20px 22px}
.answer-text{font-size:.93rem;color:var(--text-secondary);line-height:1.75;margin-bottom:16px}
.answer-text strong{color:var(--text-primary)}
.answer-text ul,.answer-text ol{margin:10px 0 10px 20px;display:flex;flex-direction:column;gap:6px}
.answer-text li::marker{color:var(--primary)}
.answer-text code{background:rgba(139,92,246,.1);color:var(--primary);padding:1px 6px;border-radius:4px;font-family:var(--mono);font-size:.86em;border:1px solid rgba(139,92,246,.18)}

/* Code block */
.code-block{margin:14px 0 0;border-radius:12px;overflow:hidden;background:var(--code-bg);border:1px solid rgba(255,255,255,.06);box-shadow:0 6px 24px rgba(0,0,0,.2)}
.code-block-header{display:flex;align-items:center;justify-content:space-between;padding:9px 16px;background:rgba(255,255,255,.05);border-bottom:1px solid rgba(255,255,255,.07)}
.code-lang{display:flex;align-items:center;gap:7px;font-family:var(--mono);font-size:.72rem;font-weight:600;color:#6ee7b7;text-transform:uppercase;letter-spacing:.08em}
.code-lang::before{content:'';display:inline-block;width:8px;height:8px;border-radius:50%;background:#10b981}
.btn-copy-code{display:flex;align-items:center;gap:5px;padding:3px 10px;background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.1);border-radius:5px;color:#94a3b8;font-size:.73rem;font-weight:600;cursor:pointer;font-family:'Inter',sans-serif;transition:all .2s ease}
.btn-copy-code:hover{background:rgba(255,255,255,.14);color:#fff}
.btn-copy-code.copied{background:rgba(16,185,129,.2);border-color:rgba(16,185,129,.3);color:#6ee7b7}
.code-block pre{padding:18px 20px;overflow-x:auto;font-family:var(--mono);font-size:.85rem;color:var(--code-text);line-height:1.75;white-space:pre;margin:0}

/* Syntax tokens */
.t-kw{color:#c084fc;font-weight:600}
.t-fn{color:#6ee7b7}
.t-str{color:#fca5a5}
.t-num{color:#fcd34d}
.t-cmt{color:#64748b;font-style:italic}
.t-op{color:#94a3b8}
.t-tbl{color:#7dd3fc}
.t-pg{color:#fb923c}   /* pg_ system objects */
.t-type{color:#a5f3fc} /* PostgreSQL-specific types */

/* Callout boxes */
.key-takeaway{display:flex;align-items:flex-start;gap:12px;padding:12px 16px;border-radius:10px;margin-top:14px;background:rgba(16,185,129,.07);border:1.5px solid rgba(16,185,129,.2)}
.key-takeaway i{color:var(--secondary);font-size:.95rem;margin-top:2px;flex-shrink:0}
.key-takeaway p{font-size:.86rem;color:var(--text-secondary);line-height:1.6}
.key-takeaway strong{color:var(--secondary)}
.gotcha-box{display:flex;align-items:flex-start;gap:12px;padding:12px 16px;border-radius:10px;margin-top:12px;background:rgba(239,68,68,.07);border:1.5px solid rgba(239,68,68,.22)}
.gotcha-box i{color:#ef4444;font-size:.95rem;margin-top:2px;flex-shrink:0}
.gotcha-box p{font-size:.86rem;color:var(--text-secondary);line-height:1.6}
.gotcha-box strong{color:#ef4444}

/* Compare table */
.compare-table{width:100%;border-collapse:collapse;margin-top:12px;font-size:.83rem;border-radius:10px;overflow:hidden;border:2px solid var(--border)}
.compare-table thead th{background:rgba(139,92,246,.1);padding:9px 14px;text-align:left;font-weight:700;color:var(--text-primary);border-bottom:2px solid var(--border)}
.compare-table tbody td{padding:8px 14px;border-bottom:1px solid var(--border);color:var(--text-secondary)}
.compare-table tbody tr:last-child td{border-bottom:none}
.compare-table tbody tr:hover{background:var(--bg-secondary)}

/* ── PANEL HEADER ── */
.panel-header{display:flex;align-items:center;justify-content:space-between;padding:14px 20px;background:rgba(139,92,246,.1);border-bottom:2px solid var(--border);font-weight:700;font-size:.95rem;color:var(--text-primary)}
.panel-header>span{display:flex;align-items:center;gap:8px}
.panel-header>span i{color:var(--primary)}

/* ── PROGRESS CARD ── */
.progress-card{background:var(--bg-card);border-radius:16px;border:2px solid var(--border);box-shadow:0 4px 20px var(--shadow);overflow:hidden}
.progress-body{display:flex;align-items:center;gap:24px;padding:18px 22px;flex-wrap:wrap}
.progress-stat{display:flex;flex-direction:column;align-items:center;gap:2px}
.ps-value{font-family:var(--mono);font-size:1.6rem;font-weight:800;background:var(--gradient);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.ps-label{font-size:.76rem;color:var(--text-secondary);font-weight:600}
.progress-bar-full{flex:1;min-width:120px}
.progress-bar-fill-full{height:8px;background:var(--bg-secondary);border-radius:4px;border:1px solid var(--border);overflow:hidden;margin-bottom:4px}
.progress-pct{font-size:.78rem;font-weight:700;color:var(--primary);font-family:var(--mono)}
.btn-clear-progress{display:flex;align-items:center;gap:6px;padding:6px 13px;border-radius:8px;font-size:.8rem;font-weight:600;background:none;border:1.5px solid var(--border);color:var(--text-secondary);cursor:pointer;font-family:'Inter',sans-serif;transition:all .2s ease}
.btn-clear-progress:hover{border-color:#ef4444;color:#ef4444}

/* ── EMPTY STATE ── */
.empty-state{text-align:center;padding:60px 20px;color:var(--text-secondary);display:flex;flex-direction:column;align-items:center;gap:12px}
.empty-state i{font-size:3rem;opacity:.25}
.empty-state h3{font-size:1.2rem;color:var(--text-primary)}
.btn-reset-filters{display:inline-flex;align-items:center;gap:7px;padding:10px 22px;border-radius:10px;margin-top:8px;background:var(--gradient);color:#fff;border:none;font-size:.9rem;font-weight:600;cursor:pointer;font-family:'Inter',sans-serif}

/* ── NOTIFICATION ── */
.notification{position:fixed;top:80px;right:20px;padding:14px 22px;background:var(--gradient);color:#fff;border-radius:10px;box-shadow:0 4px 20px rgba(139,92,246,.4);transform:translateX(calc(100% + 40px));opacity:0;transition:transform .4s ease,opacity .4s ease;z-index:1000;font-weight:500;display:flex;align-items:center;gap:9px;font-size:.92rem;pointer-events:none}
.notification.show{transform:translateX(0);opacity:1;pointer-events:auto}
.notification.success{background:linear-gradient(135deg,#10b981,#059669)}
.notification.error{background:linear-gradient(135deg,#ef4444,#dc2626)}
.notification.warning{background:linear-gradient(135deg,#f59e0b,#d97706)}

/* ── RESPONSIVE ── */
@media(max-width:768px){
    .hero{padding:2.8rem 1.5rem 3.2rem}
    .hero-h1{font-size:1.9rem}
    .hero-para{font-size:.95rem}
    .hero-stats{gap:.8rem}
    .container{padding:1.5rem}
    .diff-tabs{flex-wrap:wrap}
    .diff-tab{flex:1;min-width:100px;justify-content:center;padding:7px 10px;font-size:.82rem}
    .study-mode-desc{display:none}
    .progress-body{gap:16px}
    .btn-bookmarks-only{margin-left:0}
}
@media(max-width:576px){
    .container{padding:1rem}
    .hero{padding:2.2rem 1rem 2.8rem}
    .hero-h1{font-size:1.65rem}
    .toolbar{padding:14px 16px;gap:12px}
    .qa-header{padding:13px 14px;gap:8px}
    .qa-question{font-size:.9rem}
    .answer-wrap{padding:16px}
    .notification{left:10px;right:10px;width:calc(100% - 20px);top:70px;transform:translateY(-100px);opacity:0}
    .notification.show{transform:translateY(0);opacity:1}
}