/* =====================================================
   Memory Management Visualizer — Stylesheet
   style.css
   ===================================================== */

/* ── Google Font ── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap');

/* ── CSS Variables ── */
:root {
  --bg:        #f4f5f7;
  --surface:   #ffffff;
  --surface2:  #f9fafb;
  --border:    #e2e5ea;
  --border2:   #d0d5dd;
  --txt:       #1a1d23;
  --txt2:      #4b5563;
  --txt3:      #9ca3af;
  --accent:    #2563eb;
  --accent-bg: #eff6ff;
  --green:     #16a34a;
  --green-bg:  #f0fdf4;
  --red:       #dc2626;
  --red-bg:    #fef2f2;
  --amber:     #d97706;
  --amber-bg:  #fffbeb;
  --purple:    #7c3aed;
  --purple-bg: #f5f3ff;
  --mono:      'JetBrains Mono', 'Courier New', monospace;
  --sans:      'Inter', system-ui, sans-serif;
  --radius:    8px;
  --radius-sm: 5px;
  --shadow:    0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.05);
  --shadow-md: 0 4px 12px rgba(0,0,0,.08), 0 2px 4px rgba(0,0,0,.04);
}

/* ── Reset ── */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ── Base ── */
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--txt);
  min-height: 100vh;
  font-size: 14px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* ── Scrollbar ── */
::-webkit-scrollbar       { width: 5px; height: 5px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border2); border-radius: 99px; }

/* =====================================================
   HEADER
   ===================================================== */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 14px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  position: sticky;
  top: 0;
  z-index: 50;
}

.h-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

header h1 {
  font-size: 16px;
  font-weight: 700;
  color: var(--txt);
  letter-spacing: -0.3px;
}

header p {
  font-size: 12px;
  color: var(--txt3);
  margin-top: 1px;
}

/* =====================================================
   TABS
   ===================================================== */
.tabs {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 28px;
  display: flex;
  gap: 2px;
  overflow-x: auto;
}

.tab {
  padding: 12px 18px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  color: var(--txt3);
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
  white-space: nowrap;
  user-select: none;
}

.tab:hover {
  color: var(--txt2);
}

.tab.on {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* =====================================================
   PAGE / LAYOUT
   ===================================================== */
.page {
  display: none;
  padding: 24px 28px;
  max-width: 1400px;
}

.page.on {
  display: block;
}

.row {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

.col {
  flex: 1;
  min-width: 280px;
}

/* =====================================================
   CARDS
   ===================================================== */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 14px;
  box-shadow: var(--shadow);
}

/* Card title */
.ct {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--txt3);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

/* =====================================================
   THEORY BOX
   ===================================================== */
.theory {
  background: var(--accent-bg);
  border: 1px solid #bfdbfe;
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 10px 14px;
  margin-bottom: 18px;
  font-size: 13px;
  color: #1e3a5f;
  line-height: 1.65;
}

.theory b {
  color: var(--accent);
  font-weight: 600;
}

/* =====================================================
   FORMS
   ===================================================== */
label {
  font-size: 13px;
  font-weight: 500;
  color: var(--txt2);
  margin-right: 6px;
}

input,
select {
  background: var(--surface);
  border: 1px solid var(--border2);
  color: var(--txt);
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-family: var(--mono);
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

input:focus,
select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37,99,235,.1);
}

input[type="number"] {
  width: 72px;
}

/* =====================================================
   BUTTONS
   ===================================================== */
button {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 500;
  font-family: var(--sans);
  border: 1px solid var(--border2);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--txt2);
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s, color 0.12s, box-shadow 0.12s;
  margin-right: 6px;
  margin-bottom: 6px;
  white-space: nowrap;
}

button:hover {
  background: var(--bg);
  border-color: var(--accent);
  color: var(--accent);
}

button:active {
  transform: scale(0.98);
}

button.danger {
  border-color: #fca5a5;
  color: var(--red);
  background: var(--red-bg);
}

button.danger:hover {
  background: #fee2e2;
  border-color: var(--red);
}

/* =====================================================
   BADGES
   ===================================================== */
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 99px;
  font-size: 11px;
  font-weight: 600;
  font-family: var(--mono);
  letter-spacing: 0.02em;
}

.b-blue   { background: var(--accent-bg);  color: var(--accent);  border: 1px solid #bfdbfe; }
.b-green  { background: var(--green-bg);   color: var(--green);   border: 1px solid #bbf7d0; }
.b-amber  { background: var(--amber-bg);   color: var(--amber);   border: 1px solid #fde68a; }
.b-purple { background: var(--purple-bg);  color: var(--purple);  border: 1px solid #ddd6fe; }
.b-red    { background: var(--red-bg);     color: var(--red);     border: 1px solid #fecaca; }

/* =====================================================
   STAT GRID
   ===================================================== */
.statg {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
  gap: 10px;
  margin-bottom: 12px;
}

.statb {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 8px;
  text-align: center;
}

.statv {
  font-size: 22px;
  font-weight: 700;
  font-family: var(--mono);
  color: var(--txt);
  line-height: 1;
}

.statl {
  font-size: 10px;
  font-weight: 600;
  color: var(--txt3);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: 4px;
}

/* =====================================================
   EVENT LOG
   ===================================================== */
.log {
  background: #1e1e2e;
  border: 1px solid #2d2d3e;
  border-radius: var(--radius-sm);
  padding: 8px;
  max-height: 120px;
  overflow-y: auto;
  font-family: var(--mono);
  font-size: 12px;
}

.le {
  padding: 2px 5px;
  border-radius: 3px;
  margin-bottom: 3px;
  line-height: 1.5;
}

.lok   { color: #86efac; }
.lerr  { color: #fca5a5; }
.linfo { color: #93c5fd; }
.lw    { color: #fcd34d; }

/* =====================================================
   MEMORY BAR
   ===================================================== */
.mbar {
  height: 32px;
  display: flex;
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border);
  margin-bottom: 6px;
  box-shadow: inset 0 1px 2px rgba(0,0,0,.04);
}

.ruler {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--txt3);
  font-family: var(--mono);
  margin-bottom: 8px;
}

/* =====================================================
   PAGING — PAGE TABLE ROWS
   ===================================================== */
.ptrow {
  display: grid;
  grid-template-columns: 64px 64px 24px 1fr;
  gap: 6px;
  align-items: center;
  padding: 5px 4px;
  border-bottom: 1px solid var(--border);
  font-family: var(--mono);
  font-size: 12px;
  transition: background 0.1s;
}

.ptrow:last-child  { border: none; }
.ptrow:hover       { background: var(--surface2); border-radius: 4px; }

/* =====================================================
   TABLES
   ===================================================== */
table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 12px;
}

th {
  text-align: left;
  padding: 7px 10px;
  font-size: 11px;
  font-weight: 600;
  font-family: var(--sans);
  color: var(--txt3);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-bottom: 2px solid var(--border);
  background: var(--surface2);
}

td {
  padding: 7px 10px;
  border-bottom: 1px solid var(--border);
  color: var(--txt2);
}

tr:last-child td { border: none; }
tr:hover td      { background: var(--surface2); }

/* =====================================================
   VIRTUAL MEMORY — FRAME BOXES & REFS
   ===================================================== */
.sframe {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  height: 60px;
  font-family: var(--mono);
  transition: all 0.25s ease;
  border: 1px solid var(--border);
  background: var(--surface2);
}

.sf-empty {
  background: var(--surface2);
  color: var(--txt3);
  border-style: dashed;
}

.sf-on {
  background: var(--accent-bg);
  color: var(--accent);
  border-color: #93c5fd;
  border-style: solid;
}

.ref-wrap {
  display: flex;
  gap: 5px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.rp {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--txt3);
  transition: all 0.2s;
}

.rp.cur {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  transform: scale(1.1);
  box-shadow: 0 2px 8px rgba(37,99,235,.35);
}

.rp.hit {
  background: var(--green-bg);
  border-color: #86efac;
  color: var(--green);
}

.rp.fault {
  background: var(--red-bg);
  border-color: #fca5a5;
  color: var(--red);
}

/* =====================================================
   PROCESS PANEL
   ===================================================== */
.proc-panel {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  margin-bottom: 14px;
}

.proc-title {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--accent);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 7px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.proc-title::before {
  content: '';
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
  animation: blink 2s ease-in-out infinite;
}

@keyframes blink {
  0%, 100% { opacity: 1;   }
  50%       { opacity: 0.3; }
}

/* ── Steps ── */
.step {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
  opacity: 0.3;
  transition: opacity 0.3s ease;
}

.step.done,
.step.active {
  opacity: 1;
}

.step-num {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: 1.5px solid var(--border2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  flex-shrink: 0;
  color: var(--txt3);
  background: var(--surface);
  margin-top: 1px;
}

.step.done .step-num {
  background: var(--green-bg);
  border-color: #86efac;
  color: var(--green);
}

.step.active .step-num {
  background: var(--accent-bg);
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37,99,235,.12);
}

.step-body    { flex: 1; }

.step-lbl {
  font-size: 12px;
  font-weight: 600;
  color: var(--txt3);
  margin-bottom: 2px;
}

.step.done .step-lbl   { color: var(--txt); }
.step.active .step-lbl { color: var(--accent); }

.step-det {
  font-size: 12px;
  font-family: var(--mono);
  color: var(--txt3);
  line-height: 1.55;
}

.step.done .step-det   { color: var(--txt2); }
.step.active .step-det { color: var(--txt2); }

/* ── Inline value chips inside steps ── */
.iv {
  display: inline-block;
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 11px;
  font-family: var(--mono);
  font-weight: 600;
}

.iv-b { background: var(--accent-bg);  color: var(--accent);  }
.iv-g { background: var(--green-bg);   color: var(--green);   }
.iv-a { background: var(--amber-bg);   color: var(--amber);   }
.iv-r { background: var(--red-bg);     color: var(--red);     }
.iv-p { background: var(--purple-bg);  color: var(--purple);  }

/* =====================================================
   MISC UTILITIES
   ===================================================== */
.mono { font-family: var(--mono); font-size: 12px; }
.hint { font-size: 11px; color: var(--txt3); font-family: var(--mono); }