:root {
    --bg-color: #f1f5f9;
    --card-bg: #ffffff;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --text: #1e293b;
    --danger: #ef4444;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: 600px;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 3rem;
    margin: 0;
    letter-spacing: 4px;
    background: linear-gradient(to right, #2563eb, #7c3aed);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 10px 15px rgba(37, 99, 235, 0.1);
}

.calculator-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.display-section {
    margin-bottom: 1.5rem;
}

input {
    width: 100%;
    background: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    padding: 1rem;
    color: var(--accent);
    font-size: 1.2rem;
    box-sizing: border-box;
    transition: border-color 0.3s;
}

input:focus {
    outline: none;
    border-color: var(--accent);
}

#result-display {
    margin-top: 1rem;
    padding: 1rem;
    background: rgba(37, 99, 235, 0.05);
    border-radius: 10px;
    min-height: 3rem;
    display: flex;
    align-items: center;
    word-break: break-all;
    font-weight: bold;
    color: #475569;
}

.controls {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

button {
    cursor: pointer;
    border: none;
    padding: 1rem;
    border-radius: 10px;
    font-weight: bold;
    transition: all 0.2s;
    text-transform: uppercase;
}

.controls button {
    background: var(--accent);
    color: white;
}

.controls .btn-clear {
    background: var(--danger);
    color: white;
}

.helper-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(60px, 1fr));
    gap: 0.5rem;
}

.helper-grid button {
    background: #f1f5f9;
    color: #475569;
    border: 1px solid #e2e8f0;
}

button:hover {
    filter: brightness(0.9);
    transform: translateY(-2px);
}

button:active {
    transform: translateY(0);
}

/* BACKUP DES ALTEN DESIGNS (DARK MODE)
:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --accent: #38bdf8;
    --accent-hover: #0ea5e9;
    --text: #f8fafc;
    --danger: #ef4444;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: 600px;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 3rem;
    margin: 0;
    letter-spacing: 4px;
    background: linear-gradient(to right, #38bdf8, #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 20px rgba(56, 189, 248, 0.3);
}

.calculator-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5), 0 0 15px rgba(56, 189, 248, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

input {
    width: 100%;
    background: #0f172a;
    border: 2px solid #334155;
    border-radius: 10px;
    padding: 1rem;
    color: var(--accent);
}

#result-display {
    margin-top: 1rem;
    padding: 1rem;
    background: rgba(56, 189, 248, 0.05);
    border-radius: 10px;
    color: #cbd5e1;
}

.helper-grid button {
    background: #334155;
    color: white;
}
*/