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

:root {
    --bg:        #0d1117;
    --surface:   #161b22;
    --surface2:  #1c2330;
    --border:    #30363d;
    --green:     #3fb950;
    --green-dim: #1a6b3c;
    --green-bg:  rgba(63,185,80,0.08);
    --amber:     #e3b341;
    --blue:      #58a6ff;
    --text:      #e6edf3;
    --muted:     #8b949e;
    --red:       #f85149;
    --mono:      'JetBrains Mono', monospace;
    --sans:      'Outfit', sans-serif;
}

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

body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--sans);
    min-height: 100vh;
    line-height: 1.6;
}

.page-header {
    background:
        linear-gradient(135deg, rgba(13,17,23,0.82) 0%, rgba(26,45,26,0.75) 50%, rgba(13,17,23,0.82) 100%),
        url('zahlensysteme.jpg') center/cover no-repeat;
    border-bottom: 1px solid var(--border);
    padding: 2.5rem 1.5rem 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}
.page-header::before {
    content: '01001010';
    position: absolute;
    top: 10px; left: 20px;
    font-family: var(--mono);
    font-size: 0.7rem;
    color: rgba(63,185,80,0.15);
    letter-spacing: 4px;
}
.page-header::after {
    content: 'FF A3 2D 10';
    position: absolute;
    bottom: 10px; right: 20px;
    font-family: var(--mono);
    font-size: 0.7rem;
    color: rgba(88,166,255,0.15);
    letter-spacing: 4px;
}
.page-header h1 {
    font-family: var(--mono);
    font-size: clamp(1.4rem, 4vw, 2.2rem);
    font-weight: 700;
    color: var(--green);
    letter-spacing: -0.5px;
}
.page-header p {
    color: var(--muted);
    font-size: 0.95rem;
    margin-top: 0.4rem;
}

.header-logo {
    position: absolute;
    top: 18px;
    left: 20px;
    z-index: 5;
    display: block;
    transition: transform 0.25s ease;
}

.header-logo:hover {
    transform: scale(1.05) rotate(-3deg);
}

.header-logo img {
    display: block;
    width: 100px;
    height: auto;
}

.header-content {
    text-align: center;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1.2rem 4rem;
}

.converter-card {
    background: var(--surface);
    border: 1px solid var(--green-dim);
    border-radius: 16px;
    padding: 2rem;
    margin-bottom: 2.5rem;
    box-shadow: 0 0 40px rgba(63,185,80,0.06);
}
.converter-card h2 {
    font-family: var(--mono);
    font-size: 0.85rem;
    color: var(--green);
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 8px;
}
.converter-card h2::before { content: '\25B6'; font-size: 0.6rem; }

.converter-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.2rem;
    align-items: end;
}
@media (max-width: 560px) { .converter-grid { grid-template-columns: 1fr; } }

.field-group label {
    display: block;
    font-size: 0.78rem;
    color: var(--muted);
    font-family: var(--mono);
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
}
.field-group select,
.field-group input {
    width: 100%;
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    font-family: var(--mono);
    font-size: 1rem;
    padding: 0.7rem 1rem;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
    -webkit-appearance: none;
}
.field-group select:focus,
.field-group input:focus {
    border-color: var(--green);
    box-shadow: 0 0 0 3px rgba(63,185,80,0.12);
}
.field-group input {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--green);
    letter-spacing: 1px;
}
.field-group input::placeholder { color: var(--muted); font-weight: 400; }
.field-group input.error { border-color: var(--red); color: var(--red); }

.quick-btns {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 1.4rem;
    padding-top: 1.2rem;
    border-top: 1px solid var(--border);
}
.quick-btns span {
    font-size: 0.75rem;
    color: var(--muted);
    font-family: var(--mono);
    align-self: center;
    margin-right: 4px;
}
.quick-btn {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--muted);
    font-family: var(--mono);
    font-size: 0.78rem;
    padding: 4px 12px;
    cursor: pointer;
    transition: all 0.15s;
}
.quick-btn:hover {
    border-color: var(--green);
    color: var(--green);
    background: var(--green-bg);
}

.all-systems {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem 1.2rem;
    margin-top: 1.4rem;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.8rem;
}
@media (max-width: 500px) { .all-systems { grid-template-columns: repeat(2, 1fr); } }

.sys-display { text-align: center; }
.sys-display .sys-label {
    font-family: var(--mono);
    font-size: 0.68rem;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}
.sys-display .sys-value {
    font-family: var(--mono);
    font-size: 1rem;
    font-weight: 700;
    margin-top: 3px;
    min-height: 1.4em;
    word-break: break-all;
}
.sys-display.bin .sys-value { color: var(--green); }
.sys-display.okt .sys-value { color: var(--amber); }
.sys-display.dez .sys-value { color: var(--blue);  }
.sys-display.hex .sys-value { color: #e879f9;       }

.section {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.8rem;
    margin-bottom: 1.5rem;
}
.section h2 {
    font-family: var(--mono);
    font-size: 1rem;
    font-weight: 700;
    color: var(--amber);
    margin-bottom: 1rem;
    padding-bottom: 0.6rem;
    border-bottom: 1px solid var(--border);
}
.section p {
    color: #c9d1d9;
    font-size: 0.93rem;
    margin-bottom: 0.9rem;
}
.section p:last-child { margin-bottom: 0; }

.hl-green { color: var(--green); font-family: var(--mono); font-weight: 600; }
.hl-amber { color: var(--amber); font-family: var(--mono); font-weight: 600; }
.hl-blue  { color: var(--blue);  font-family: var(--mono); font-weight: 600; }
.hl-pink  { color: #e879f9;      font-family: var(--mono); font-weight: 600; }

.stelle-table {
    width: 100%;
    border-collapse: collapse;
    font-family: var(--mono);
    font-size: 0.88rem;
    margin: 1rem 0;
    overflow-x: auto;
    display: block;
}
.stelle-table th {
    background: var(--surface2);
    color: var(--muted);
    padding: 6px 12px;
    text-align: center;
    border: 1px solid var(--border);
    font-size: 0.75rem;
    letter-spacing: 1px;
}
.stelle-table td {
    padding: 7px 12px;
    text-align: center;
    border: 1px solid var(--border);
}
.stelle-table tr:nth-child(even) td { background: var(--surface2); }
.stelle-table .potenz { color: var(--muted); font-size: 0.8rem; }
.stelle-table .ziffer { color: var(--green); font-size: 1rem; font-weight: 700; }

.systems-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    margin-top: 1rem;
}
@media (max-width: 500px) { .systems-grid { grid-template-columns: 1fr; } }

.sys-card {
    border-radius: 10px;
    padding: 1.1rem 1.2rem;
    border: 1px solid;
}
.sys-card.bin { background: rgba(63,185,80,0.07);   border-color: rgba(63,185,80,0.3);  }
.sys-card.okt { background: rgba(227,179,65,0.07);  border-color: rgba(227,179,65,0.3); }
.sys-card.dez { background: rgba(88,166,255,0.07);  border-color: rgba(88,166,255,0.3); }
.sys-card.hex { background: rgba(232,121,249,0.07); border-color: rgba(232,121,249,0.3);}

.sys-card .sc-title { font-family: var(--mono); font-weight: 700; font-size: 0.95rem; margin-bottom: 0.4rem; }
.sys-card.bin .sc-title { color: var(--green); }
.sys-card.okt .sc-title { color: var(--amber); }
.sys-card.dez .sc-title { color: var(--blue);  }
.sys-card.hex .sc-title { color: #e879f9;       }

.sys-card .sc-ziffern { font-family: var(--mono); font-size: 0.8rem; color: var(--muted); margin-bottom: 0.5rem; }
.sys-card .sc-desc    { font-size: 0.82rem; color: #8b949e; line-height: 1.4; }

.byte-visual {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
    margin: 1rem 0;
    justify-content: center;
}
.bit-cell {
    width: 40px; height: 40px;
    border-radius: 6px;
    display: flex; align-items: center; justify-content: center;
    font-family: var(--mono);
    font-weight: 700;
    font-size: 1.1rem;
    border: 1px solid var(--border);
    background: var(--surface2);
    color: var(--muted);
}
.bit-cell.one {
    background: rgba(63,185,80,0.15);
    border-color: var(--green);
    color: var(--green);
}
@media (max-width: 400px) { .bit-cell { width: 32px; height: 32px; font-size: 0.9rem; } }

.byte-label {
    text-align: center;
    font-family: var(--mono);
    font-size: 0.78rem;
    color: var(--muted);
    margin-top: 0.4rem;
}

@media (max-width: 700px) {

    .page-header {
        padding-top: 90px;
    }

    .header-logo {
        left: 50%;
        top: 10px;
        transform: translateX(-50%);
    }

    .header-logo:hover {
        transform: translateX(-50%) scale(1.05);
    }
    
     .quick-btns span {
        flex-basis: 100%;
        margin-bottom: 8px;
    }
}