* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: Arial, "Hiragino Sans", "Yu Gothic", sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    background: #f3f4f6;
    color: #222;
    transition: background-color 0.3s ease;
}

body.timer-mode {
    background: #f3f4f6;
}

body.work-mode {
    background: #fff1f2;
}

body.break-mode {
    background: #eff6ff;
}

.container {
    width: 100%;
    padding: 24px;
    display: flex;
    justify-content: center;
}

.app {
    width: 100%;
    max-width: 420px;
    background: #ffffff;
    border-radius: 20px;
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
    padding: 28px 24px;
}

.title {
    margin: 0 0 24px;
    text-align: center;
    font-size: 28px;
}

.tabs {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.tab {
    flex: 1;
    border: none;
    border-radius: 12px;
    padding: 12px 16px;
    background: #e5e7eb;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.2s;
}

.tab:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

.tab.active {
    background: #111827;
    color: #ffffff;
}

.inputs {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.inputs input {
    width: 100%;
    padding: 14px 12px;
    border: 1px solid #d1d5db;
    border-radius: 12px;
    font-size: 18px;
    text-align: center;
    outline: none;
}

.inputs input:focus {
    border-color: #2563eb;
}

.pomodoro-info {
    text-align: center;
    margin-bottom: 12px;
}

.pomodoro-info p {
    margin: 6px 0;
    font-size: 16px;
}

.display-area {
    text-align: center;
    margin: 20px 0 28px;
}

.time-display {
    margin: 0;
    font-size: 64px;
    font-weight: bold;
    letter-spacing: 2px;
}

.actions {
    display: flex;
    gap: 12px;
}

.action-btn {
    flex: 1;
    border: none;
    border-radius: 12px;
    padding: 14px 16px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.2s;
}

.action-btn:hover {
    opacity: 0.92;
    transform: translateY(-1px);
}

.start {
    background: #22c55e;
    color: #fff;
}

.stop {
    background: #f59e0b;
    color: #fff;
}

.reset {
    background: #6b7280;
    color: #fff;
}