:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5a623;
    --background-color: #f0f2f5;
    --text-color: #333;
    --card-bg: #fff;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --font-family: 'Helvetica Neue', sans-serif;
    --gradient: linear-gradient(to right top, #d16ba5, #c777b9, #ba83ca, #aa8fd8, #9a9ae1, #8aa7ec, #7ab3f4, #69bff8, #52cffe, #41dfff, #46eefa, #5ffbf1);
    --btn-hover: #357abd;
}

[data-theme="dark"] {
    --primary-color: #6db3f8;
    --secondary-color: #f5a623;
    --background-color: #1a1a2e;
    --text-color: #e0e0e0;
    --card-bg: #16213e;
    --shadow-color: rgba(0, 0, 0, 0.4);
    --gradient: linear-gradient(to right top, #0f0c29, #302b63, #24243e);
    --btn-hover: #5a9fd4;
}

* {
    transition: background-color 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-image: var(--gradient);
}

.container {
    text-align: center;
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 10px 20px var(--shadow-color);
    max-width: 90%;
    width: 500px;
    position: relative;
}

h1 {
    color: var(--primary-color);
    margin-bottom: 2rem;
}

button {
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    padding: 0.8rem 1.5rem;
    border-radius: 0.5rem;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
    box-shadow: 0 4px 10px var(--shadow-color);
}

button:hover {
    background-color: var(--btn-hover);
    transform: translateY(-2px);
}

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

.theme-toggle {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.4rem;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: none;
    transition: transform 0.3s ease;
}

.theme-toggle:hover {
    background: none;
    transform: rotate(30deg);
}