:root {
    --bg: #f4f7fb;
    --card-bg: #ffffff;
    --text: #1b1f23;
    --primary: #2563eb;
    --primary-hover: #1e4ec7;
    --radius: 14px;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
}

/* DARK THEME */
.dark {
    --bg: #0f172a;
    --card-bg: #1e293b;
    --text: #e2e8f0;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
}

body {
    margin: 0;
    font-family: Inter, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
}

/* HEADER */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 40px;
    background: var(--card-bg);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

header h1 {
    font-size: 28px;
    font-weight: 700;
}

.controls button,
.controls select {
    margin-left: 10px;
    padding: 8px 14px;
    font-size: 15px;
    border-radius: 8px;
    border: 1px solid #cbd5e1;
    background: var(--card-bg);
    color: var(--text);
}

/* TABS */
.tabs {
    display: flex;
    gap: 10px;
    padding: 15px 30px;
}

.tabs button {
    padding: 10px 20px;
    border-radius: 10px;
    border: 0;
    background: var(--primary);
    color: white;
    cursor: pointer;
    font-size: 16px;
}

.tabs button:hover {
    background: var(--primary-hover);
}

/* SECTIONS */
section {
    display: none;
    padding: 30px;
}

section.active {
    display: block;
}

/* CARD */
.result-card, section input, section select {
    width: 100%;
    max-width: 500px;
}

section input,
section select {
    padding: 12px;
    margin-top: 5px;
    margin-bottom: 20px;
    border-radius: 10px;
    border: 1px solid #cbd5e1;
    background: var(--card-bg);
    color: var(--text);
    font-size: 16px;
}

section button {
    padding: 14px 25px;
    background: var(--primary);
    color: white;
    border: 0;
    border-radius: 12px;
    font-size: 16px;
    cursor: pointer;
    margin-top: 10px;
}

section button:hover {
    background: var(--primary-hover);
}

.result-card {
    background: var(--card-bg);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    font-size: 17px;
    margin-top: 20px;
}