:root {
    --bg-main: #1f5fd3;
    --bg-accent: #1143a3;
    --text-main: #ffffff;
    --panel-surface: #f8fbff;
    --button-surface: #0e2f74;
    --button-text: #ffffff;
}

:root[data-theme="dark"] {
    --bg-main: #0a1229;
    --bg-accent: #16305f;
    --text-main: #edf2ff;
    --panel-surface: #1a2340;
    --button-surface: #d7e5ff;
    --button-text: #0a1229;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    min-height: 100vh;
    display: grid;
    place-items: center;
    background: radial-gradient(circle at 20% 10%, #3a80ff 0%, var(--bg-main) 45%, var(--bg-accent) 100%);
    color: var(--text-main);
}

.app {
    width: min(680px, 92vw);
}

h1 {
    margin: 0 0 1rem;
    text-align: center;
    font-size: clamp(1.8rem, 4vw, 2.5rem);
}

.theme-switcher {
    margin-top: 1rem;
    text-align: center;
}

#themeToggle {
    border: 0;
    padding: 0.7rem 1.25rem;
    border-radius: 999px;
    background: var(--button-surface);
    color: var(--button-text);
    cursor: pointer;
    font-weight: 700;
}

#themeToggle:hover {
    filter: brightness(1.05);
}