:root {
    --bg-color: #f5f5f5;
    --container-bg: white;
    --text-color: #333;
    --input-border: #ddd;
    --primary-color: #FA8072; /* Salmon */
    --primary-hover: #E9967A; /* Dark Salmon */
    --container-border: #FFC0CB; /* Pink */
    --error-color: #FF6347; /* Tomato */
    --input-focus-shadow: rgba(250, 128, 114, 0.2);
    --result-box-bg: #f8f9fa;
}

.dark-mode {
    --bg-color: #222;
    --container-bg: #333;
    --text-color: #f0f0f0;
    --input-border: #555;
    --primary-color: #FF6347; /* Tomato - slightly darker for better contrast in dark mode */
    --primary-hover: #FA8072; /* Salmon */
    --container-border: #FF6347; /* Tomato */
    --error-color: #FF6347; /* Tomato */
    --input-focus-shadow: rgba(255, 99, 71, 0.3);
    --result-box-bg: #444;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Arial', sans-serif;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s, box-shadow 0.3s;
}

body {
    background-color: var(--bg-color);
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

#dark-mode-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: var(--container-bg);
    border: 1px solid var(--input-border);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 5px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    z-index: 10;
}

#dark-mode-toggle:hover {
    transform: scale(1.05);
}

#dark-mode-toggle:active {
    transform: scale(0.95);
}

#dark-mode-toggle svg {
    width: 24px;
    height: 24px;
    stroke: var(--primary-color);
    position: absolute;
    transition: opacity 0.3s, transform 0.5s;
}

.sun-icon {
    opacity: 1;
    transform: rotate(0);
}

.moon-icon {
    opacity: 0;
    transform: rotate(90deg);
}

.dark-mode .sun-icon {
    opacity: 0;
    transform: rotate(-90deg);
}

.dark-mode .moon-icon {
    opacity: 1;
    transform: rotate(0);
}

.container {
    background-color: var(--container-bg);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    border: 2px solid var(--container-border);
    width: 90%;
    max-width: 500px;
    padding: 2rem;
}

h1 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--primary-hover);
    text-shadow: 1px 1px 1px rgba(0,0,0,0.1);
}

h2 {
    margin-top: 1.5rem;
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
    color: var(--primary-hover);
}

.form-group {
    margin-bottom: 1rem;
}

input {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid var(--input-border);
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s;
    background-color: var(--container-bg);
    color: var(--text-color);
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--input-focus-shadow);
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    padding: 0.8rem 1.5rem;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s;
}

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

.screen {
    display: none;
}

.screen.active {
    display: block;
}

.result-box {
    display: flex;
    align-items: center;
    background-color: var(--result-box-bg);
    border: 1px solid var(--input-border);
    border-radius: 4px;
    padding: 0.8rem;
    margin-top: 0.5rem;
}

#shortened-url {
    flex-grow: 1;
    word-break: break-all;
    color: var(--text-color);
}

#copy-button {
    flex-shrink: 0;
    padding: 0.5rem 1rem;
    margin-left: 0.5rem;
}

.hidden {
    display: none;
}

.error-message {
    color: var(--error-color);
    margin-top: 0.5rem;
    text-align: center;
}

#shorten-button {
    width: 100%;
    margin-top: 1rem;
}

#password-submit {
    margin-top: 1.2rem;
    width: 100%;
}