@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700&display=swap');

/* ── Design tokens ──────────────────────────────────────────── */
:root {
    --primary:        #4f46e5;
    --primary-light:  #818cf8;
    --accent:         #22c55e;
    --accent-glow:    rgba(34, 197, 94, 0.35);
    --danger:         #ef4444;
    --warning:        #f59e0b;

    --bg-base:        #0f172a;
    --bg-card:        rgba(255, 255, 255, 0.04);
    --bg-card-hover:  rgba(255, 255, 255, 0.07);
    --border:         rgba(255, 255, 255, 0.09);
    --border-focus:   rgba(99, 102, 241, 0.6);

    --text:           #f1f5f9;
    --text-dim:       #94a3b8;
    --text-muted:     #475569;

    --radius-sm:  10px;
    --radius:     16px;
    --radius-lg:  24px;
    --radius-xl:  32px;

    --shadow:     0 20px 60px rgba(0, 0, 0, 0.5);
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html { scroll-behavior: smooth; }

body {
    font-family: 'Outfit', sans-serif;
    background: var(--bg-base);
    color: var(--text);
    min-height: 100vh;
    overflow-x: hidden;
}

/* ── Animated background ────────────────────────────────────── */
body::before,
body::after {
    content: '';
    position: fixed;
    border-radius: 50%;
    filter: blur(120px);
    z-index: 0;
    pointer-events: none;
}
body::before {
    width: 600px; height: 600px;
    background: var(--primary);
    opacity: 0.12;
    top: -100px; left: -100px;
    animation: drift 12s ease-in-out infinite alternate;
}
body::after {
    width: 400px; height: 400px;
    background: var(--accent);
    opacity: 0.08;
    bottom: -80px; right: -80px;
    animation: drift 15s ease-in-out infinite alternate-reverse;
}
@keyframes drift {
    from { transform: translate(0, 0); }
    to   { transform: translate(40px, 40px); }
}

/* ── Layout ─────────────────────────────────────────────────── */
.app-wrapper {
    position: relative;
    z-index: 1;
    max-width: 860px;
    margin: 0 auto;
    padding: 32px 20px 80px;
}

/* ── Header ─────────────────────────────────────────────────── */
.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 16px;
}

.app-header h1 {
    font-size: clamp(1.3rem, 3vw, 1.8rem);
    font-weight: 700;
    background: linear-gradient(135deg, #f1f5f9, var(--primary-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.app-header p {
    font-size: 0.82rem;
    color: var(--text-dim);
    margin-top: 2px;
}

/* ── Buttons ─────────────────────────────────────────────────── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    font-family: 'Outfit', sans-serif;
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}
.btn-ghost {
    background: var(--bg-card);
    border: 1px solid var(--border);
    color: var(--text-dim);
}
.btn-ghost:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary-light);
    color: var(--text);
    transform: translateY(-1px);
}
.btn-primary {
    background: linear-gradient(135deg, var(--primary), #6366f1);
    color: #fff;
    box-shadow: 0 4px 20px rgba(79, 70, 229, 0.4);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(79, 70, 229, 0.55);
    filter: brightness(1.1);
}
.btn-accent {
    background: linear-gradient(135deg, #16a34a, var(--accent));
    color: #fff;
    box-shadow: 0 4px 20px var(--accent-glow);
    width: 100%;
    justify-content: center;
    padding: 14px;
    font-size: 1rem;
    border-radius: var(--radius);
}
.btn-accent:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px var(--accent-glow);
    filter: brightness(1.08);
}
.btn-accent:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    transform: none;
}
.btn-sm {
    padding: 7px 14px;
    font-size: 0.8rem;
}

/* ── Card ────────────────────────────────────────────────────── */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: 28px 32px;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    transition: var(--transition);
}
.card:hover { border-color: rgba(255,255,255,0.13); }

.card-title {
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--primary-light);
    margin-bottom: 18px;
}

/* ── Class selector ──────────────────────────────────────────── */
.class-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
}

.class-btn {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 18px 12px;
    cursor: pointer;
    text-align: center;
    transition: var(--transition);
    color: var(--text);
    font-family: 'Outfit', sans-serif;
}
.class-btn:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary-light);
    transform: translateY(-2px);
}
.class-btn.active {
    border-color: var(--primary);
    background: rgba(79, 70, 229, 0.12);
    box-shadow: 0 0 0 1px var(--primary);
}
.class-btn .class-letter {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: 6px;
}
.class-btn .class-label {
    font-size: 0.72rem;
    color: var(--text-dim);
}
.class-info-bar {
    margin-top: 14px;
    padding: 12px 16px;
    background: rgba(99,102,241,0.08);
    border: 1px solid rgba(99,102,241,0.2);
    border-radius: var(--radius-sm);
    font-size: 0.82rem;
    color: var(--text-dim);
    display: none;
    gap: 16px;
    flex-wrap: wrap;
}
.class-info-bar.visible { display: flex; }
.class-info-bar span b { color: var(--text); }

/* ── Inputs ──────────────────────────────────────────────────── */
.input-group { margin-bottom: 18px; }
.input-group label {
    display: block;
    font-size: 0.76rem;
    color: var(--text-dim);
    font-weight: 500;
    margin-bottom: 7px;
    letter-spacing: 0.04em;
}

.ip-octets {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}

input[type="text"],
input[type="number"],
select {
    width: 100%;
    padding: 12px 14px;
    background: rgba(255,255,255,0.05);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: 'Outfit', sans-serif;
    font-size: 0.92rem;
    transition: var(--transition);
}
input[type="text"]:focus,
input[type="number"]:focus,
select:focus {
    outline: none;
    border-color: var(--border-focus);
    background: rgba(255,255,255,0.08);
    box-shadow: 0 0 0 3px rgba(99,102,241,0.15);
}
input::placeholder { color: var(--text-muted); }
input.invalid { border-color: var(--danger) !important; box-shadow: 0 0 0 3px rgba(239,68,68,0.15) !important; }
input.valid   { border-color: var(--accent)  !important; box-shadow: 0 0 0 3px rgba(34,197,94,0.1)  !important; }

select {
    appearance: none;
    cursor: pointer;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
}
select option { background: #1e2035; }

.ip-validation-msg {
    font-size: 0.75rem;
    margin-top: 7px;
    min-height: 18px;
    transition: var(--transition);
}
.ip-validation-msg.ok  { color: var(--accent); }
.ip-validation-msg.err { color: var(--danger); }

/* ── Mode tabs ───────────────────────────────────────────────── */
.mode-tabs {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    margin-bottom: 20px;
}
.mode-tab {
    padding: 10px 8px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    color: var(--text-dim);
    font-family: 'Outfit', sans-serif;
    font-size: 0.78rem;
    font-weight: 500;
    cursor: pointer;
    text-align: center;
    transition: var(--transition);
}
.mode-tab:hover   { border-color: var(--primary-light); color: var(--text); }
.mode-tab.active  { border-color: var(--accent); background: rgba(34,197,94,0.1); color: var(--accent); }

/* ── Results ─────────────────────────────────────────────────── */
#results-section { display: none; }
#results-section.visible { display: block; }

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 12px;
}

.result-item {
    background: rgba(255,255,255,0.03);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 16px;
    transition: var(--transition);
}
.result-item:hover { background: rgba(255,255,255,0.06); }
.result-item .r-label {
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 5px;
}
.result-item .r-value {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text);
    word-break: break-all;
}
.result-item.highlight .r-value { color: var(--accent); }
.result-item.highlight-purple .r-value { color: var(--primary-light); }

.range-bar {
    margin-top: 14px;
    padding: 12px 16px;
    background: rgba(34,197,94,0.06);
    border: 1px solid rgba(34,197,94,0.2);
    border-radius: var(--radius-sm);
    font-size: 0.84rem;
    color: var(--text-dim);
}
.range-bar b { color: var(--accent); }

/* ── Subnet table ────────────────────────────────────────────── */
#subnet-section { display: none; }
#subnet-section.visible { display: block; }

.subnet-controls {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 18px;
    flex-wrap: wrap;
}
.subnet-controls label { font-size: 0.8rem; color: var(--text-dim); white-space: nowrap; }
.subnet-controls input { width: 80px; }

.table-wrapper { overflow-x: auto; border-radius: var(--radius); }
table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.82rem;
}
thead th {
    padding: 11px 14px;
    text-align: left;
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-dim);
    background: rgba(255,255,255,0.03);
    border-bottom: 1px solid var(--border);
    white-space: nowrap;
}
tbody tr {
    border-bottom: 1px solid rgba(255,255,255,0.04);
    transition: var(--transition);
}
tbody tr:hover { background: rgba(255,255,255,0.04); }
tbody td {
    padding: 10px 14px;
    color: var(--text-dim);
    font-family: 'Courier New', monospace;
    font-size: 0.8rem;
}
tbody td:first-child { color: var(--text-muted); font-family: 'Outfit', sans-serif; }
tbody td.highlight   { color: var(--accent); }

.table-footer {
    margin-top: 10px;
    font-size: 0.76rem;
    color: var(--text-muted);
    text-align: right;
}

/* ── Theory modal ────────────────────────────────────────────── */
.modal-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.75);
    z-index: 100;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 40px 20px;
    backdrop-filter: blur(6px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
    overflow-y: auto;
}
.modal-backdrop.open { opacity: 1; pointer-events: all; }

.modal {
    background: #131929;
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    width: 100%;
    max-width: 740px;
    padding: 36px;
    box-shadow: var(--shadow);
    transform: translateY(20px);
    transition: transform 0.3s;
}
.modal-backdrop.open .modal { transform: translateY(0); }

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 28px;
}
.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 700;
    background: linear-gradient(135deg, #f1f5f9, var(--primary-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.modal-close {
    background: none;
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-dim);
    width: 34px; height: 34px;
    cursor: pointer;
    font-size: 1.1rem;
    display: flex; align-items: center; justify-content: center;
    transition: var(--transition);
}
.modal-close:hover { border-color: var(--danger); color: var(--danger); }

.theory-section {
    margin-bottom: 22px;
    padding: 18px 20px;
    background: rgba(255,255,255,0.03);
    border-left: 3px solid var(--primary);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.theory-section:nth-child(even)   { border-left-color: var(--accent); }
.theory-section:nth-child(3n)     { border-left-color: var(--primary-light); }

.theory-section h3 {
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--primary-light);
    margin-bottom: 8px;
}
.theory-section:nth-child(even) h3 { color: var(--accent); }

.theory-section p {
    font-size: 0.88rem;
    color: var(--text-dim);
    line-height: 1.7;
}

/* ── Spinner ─────────────────────────────────────────────────── */
.spinner {
    width: 18px; height: 18px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    display: inline-block;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── Alerts ──────────────────────────────────────────────────── */
.alert {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.84rem;
    margin-top: 14px;
    display: none;
}
.alert.visible { display: block; }
.alert-error { background: rgba(239,68,68,0.1); border: 1px solid rgba(239,68,68,0.3); color: #fca5a5; }
.alert-warn  { background: rgba(245,158,11,0.1); border: 1px solid rgba(245,158,11,0.3); color: #fcd34d; }

/* ── Responsive ──────────────────────────────────────────────── */
@media (max-width: 600px) {
    .card { padding: 22px 18px; border-radius: var(--radius-lg); }
    .class-grid { grid-template-columns: repeat(3, 1fr); gap: 8px; }
    .class-btn  { padding: 14px 8px; }
    .mode-tabs  { grid-template-columns: 1fr; }
    .results-grid { grid-template-columns: repeat(2, 1fr); }
    .modal { padding: 24px 18px; }
    .ip-octets { grid-template-columns: repeat(2, 1fr); }
}