:root {
    --bg-color: #f0f4f8;
    --card-bg-color: #ffffff;
    --text-color: #121826;
    --secondary-text-color: #6b7280;
    --border-color: #e5e7eb;
    --price-up-color: #16a34a;
    --price-down-color: #dc2626;
    --accent-color: #2563eb;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body.dark {
    --bg-color: #121826;
    --card-bg-color: #1a2233;
    --text-color: #f0f4f8;
    --secondary-text-color: #9aa5b9;
    --border-color: #2c3a58;
    --price-up-color: #22c55e;
    --price-down-color: #ef4444;
    --accent-color: #3b82f6;
    --shadow-color: rgba(0, 0, 0, 0.2);
}

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

header {
    background-color: var(--card-bg-color);
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 10;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    font-size: 1.75rem;
    font-weight: 700;
}

.theme-btn {
    background: none;
    border: 2px solid var(--border-color);
    color: var(--secondary-text-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}
.theme-btn:hover {
    border-color: var(--accent-color);
    color: var(--accent-color);
}
.theme-btn svg {
    width: 20px;
    height: 20px;
}
.moon { display: none; }
body.dark .sun { display: none; }
body.dark .moon { display: block; }

main {
    padding: 2rem 0;
}

.search-container {
    margin-bottom: 2rem;
}

#search-input {
    width: 100%;
    padding: 0.8rem 1rem;
    font-size: 1rem;
    font-family: 'Poppins', sans-serif;
    background-color: var(--card-bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: border-color 0.3s, box-shadow 0.3s;
}

#search-input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent-color) 30%, transparent);
}

#crypto-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.coin-card {
    background-color: var(--card-bg-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    transition: transform 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
    cursor: default;
}

.coin-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px var(--shadow-color);
}

.card-header {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.coin-logo {
    width: 50px;
    height: 50px;
}

.coin-titles {
    line-height: 1.2;
}

.coin-name {
    font-size: 1.25rem;
    font-weight: 600;
}

.coin-symbol {
    font-size: 0.9rem;
    text-transform: uppercase;
    color: var(--secondary-text-color);
}

.coin-price {
    font-family: 'Roboto Mono', monospace;
    font-size: 1.75rem;
    font-weight: 500;
}

.coin-change {
    font-family: 'Roboto Mono', monospace;
    font-size: 1rem;
    font-weight: 500;
}

.price-up {
    color: var(--price-up-color);
}

.price-down {
    color: var(--price-down-color);
}

.card-footer {
    border-top: 1px solid var(--border-color);
    padding-top: 1rem;
    margin-top: auto;
}

.market-cap-label {
    font-size: 0.8rem;
    color: var(--secondary-text-color);
    margin-bottom: 0.25rem;
}

.market-cap {
    font-family: 'Roboto Mono', monospace;
    font-size: 1rem;
}

footer {
    text-align: center;
    padding: 2rem 0;
    margin-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--secondary-text-color);
}

.creator-credit {
    font-weight: 600;
    margin-bottom: 0.5rem;
}

footer a {
    color: var(--accent-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

.loader {
    width: 50px;
    height: 50px;
    border: 5px solid var(--border-color);
    border-top-color: var(--accent-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 4rem auto;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}